From: Mikhail Terekhov Date: Wed, 18 Jan 2017 13:56:35 +0000 (-0500) Subject: Revert README and HOWTO files renaming. X-Git-Tag: fio-2.18~38^2~3 X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=f3c38c4b2f568edd83400e84d57f3c38346300d5;hp=74ddd43820cb223513def1f7d856b32874d81d21 Revert README and HOWTO files renaming. github doesn't support Sphinx extencions to ReStructured text format. --- diff --git a/HOWTO b/HOWTO new file mode 100644 index 00000000..d63fff7c --- /dev/null +++ b/HOWTO @@ -0,0 +1,3375 @@ +How fio works +------------- + +The first step in getting fio to simulate a desired I/O workload, is writing a +job file describing that specific setup. A job file may contain any number of +threads and/or files -- the typical contents of the job file is a *global* +section defining shared parameters, and one or more job sections describing the +jobs involved. When run, fio parses this file and sets everything up as +described. If we break down a job from top to bottom, it contains the following +basic parameters: + +`I/O type`_ + + Defines the I/O pattern issued to the file(s). We may only be reading + sequentially from this file(s), or we may be writing randomly. Or even + mixing reads and writes, sequentially or randomly. + Should we be doing buffered I/O, or direct/raw I/O? + +`Block size`_ + + In how large chunks are we issuing I/O? This may be a single value, + or it may describe a range of block sizes. + +`I/O size`_ + + How much data are we going to be reading/writing. + +`I/O engine`_ + + How do we issue I/O? We could be memory mapping the file, we could be + using regular read/write, we could be using splice, async I/O, or even + SG (SCSI generic sg). + +`I/O depth`_ + + If the I/O engine is async, how large a queuing depth do we want to + maintain? + + +`Target file/device`_ + + How many files are we spreading the workload over. + +`Threads, processes and job synchronization`_ + + How many threads or processes should we spread this workload over. + +The above are the basic parameters defined for a workload, in addition there's a +multitude of parameters that modify other aspects of how this job behaves. + + +Command line options +-------------------- + +.. option:: --debug=type + + Enable verbose tracing of various fio actions. May be ``all`` for all types + or individual types separated by a comma (eg ``--debug=file,mem`` will + enable file and memory debugging). Currently, additional logging is + available for: + + *process* + Dump info related to processes. + *file* + Dump info related to file actions. + *io* + Dump info related to I/O queuing. + *mem* + Dump info related to memory allocations. + *blktrace* + Dump info related to blktrace setup. + *verify* + Dump info related to I/O verification. + *all* + Enable all debug options. + *random* + Dump info related to random offset generation. + *parse* + Dump info related to option matching and parsing. + *diskutil* + Dump info related to disk utilization updates. + *job:x* + Dump info only related to job number x. + *mutex* + Dump info only related to mutex up/down ops. + *profile* + Dump info related to profile extensions. + *time* + Dump info related to internal time keeping. + *net* + Dump info related to networking connections. + *rate* + Dump info related to I/O rate switching. + *compress* + Dump info related to log compress/decompress. + *?* or *help* + Show available debug options. + +.. option:: --parse-only + + Parse options only, don\'t start any I/O. + +.. option:: --output=filename + + Write output to file `filename`. + +.. option:: --bandwidth-log + + Generate aggregate bandwidth logs. + +.. option:: --minimal + + Print statistics in a terse, semicolon-delimited format. + +.. option:: --append-terse + + Print statistics in selected mode AND terse, semicolon-delimited format. + **deprecated**, use :option:`--output-format` instead to select multiple + formats. + +.. option:: --output-format=type + + Set the reporting format to `normal`, `terse`, `json`, or `json+`. Multiple + formats can be selected, separate by a comma. `terse` is a CSV based + format. `json+` is like `json`, except it adds a full dump of the latency + buckets. + +.. option:: --terse-version=type + + Set terse version output format (default 3, or 2 or 4). + +.. option:: --version + + Print version info and exit. + +.. option:: --help + + Print this page. + +.. option:: --cpuclock-test + + Perform test and validation of internal CPU clock. + +.. option:: --crctest=test + + Test the speed of the builtin checksumming functions. If no argument is + given, all of them are tested. Or a comma separated list can be passed, in + which case the given ones are tested. + +.. option:: --cmdhelp=command + + Print help information for `command`. May be ``all`` for all commands. + +.. option:: --enghelp=[ioengine[,command]] + + List all commands defined by :option:`ioengine`, or print help for `command` + defined by :option:`ioengine`. If no :option:`ioengine` is given, list all + available ioengines. + +.. option:: --showcmd=jobfile + + Turn a job file into command line options. + +.. option:: --readonly + + Turn on safety read-only checks, preventing writes. The ``--readonly`` + option is an extra safety guard to prevent users from accidentally starting + a write workload when that is not desired. Fio will only write if + `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used + as an extra precaution as ``--readonly`` will also enable a write check in + the I/O engine core to prevent writes due to unknown user space bug(s). + +.. option:: --eta=when + + When real-time ETA estimate should be printed. May be `always`, `never` or + `auto`. + +.. option:: --eta-newline=time + + Force a new line for every `time` period passed. + +.. option:: --status-interval=time + + Force full status dump every `time` period passed. + +.. option:: --section=name + + Only run specified section in job file. Multiple sections can be specified. + The ``--section`` option allows one to combine related jobs into one file. + E.g. one job file could define light, moderate, and heavy sections. Tell + fio to run only the "heavy" section by giving ``--section=heavy`` + command line option. One can also specify the "write" operations in one + section and "verify" operation in another section. The ``--section`` option + only applies to job sections. The reserved *global* section is always + parsed and used. + +.. option:: --alloc-size=kb + + Set the internal smalloc pool to this size in kb (def 1024). The + ``--alloc-size`` switch allows one to use a larger pool size for smalloc. + If running large jobs with randommap enabled, fio can run out of memory. + Smalloc is an internal allocator for shared structures from a fixed size + memory pool. The pool size defaults to 16M and can grow to 8 pools. + + NOTE: While running :file:`.fio_smalloc.*` backing store files are visible + in :file:`/tmp`. + +.. option:: --warnings-fatal + + All fio parser warnings are fatal, causing fio to exit with an + error. + +.. option:: --max-jobs=nr + + Maximum number of threads/processes to support. + +.. option:: --server=args + + Start a backend server, with `args` specifying what to listen to. + See `Client/Server`_ section. + +.. option:: --daemonize=pidfile + + Background a fio server, writing the pid to the given `pidfile` file. + +.. option:: --client=hostname + + Instead of running the jobs locally, send and run them on the given host or + set of hosts. See `Client/Server`_ section. + +.. option:: --remote-config=file + + Tell fio server to load this local file. + +.. option:: --idle-prof=option + + Report cpu idleness on a system or percpu basis + ``--idle-prof=system,percpu`` or + run unit work calibration only ``--idle-prof=calibrate``. + +.. option:: --inflate-log=log + + Inflate and output compressed log. + +.. option:: --trigger-file=file + + Execute trigger cmd when file exists. + +.. option:: --trigger-timeout=t + + Execute trigger at this time. + +.. option:: --trigger=cmd + + Set this command as local trigger. + +.. option:: --trigger-remote=cmd + + Set this command as remote trigger. + +.. option:: --aux-path=path + + Use this path for fio state generated files. + +Any parameters following the options will be assumed to be job files, unless +they match a job file parameter. Multiple job files can be listed and each job +file will be regarded as a separate group. Fio will :option:`stonewall` +execution between each group. + + +Job file format +--------------- + +As previously described, fio accepts one or more job files describing what it is +supposed to do. The job file format is the classic ini file, where the names +enclosed in [] brackets define the job name. You are free to use any ascii name +you want, except *global* which has special meaning. Following the job name is +a sequence of zero or more parameters, one per line, that define the behavior of +the job. If the first character in a line is a ';' or a '#', the entire line is +discarded as a comment. + +A *global* section sets defaults for the jobs described in that file. A job may +override a *global* section parameter, and a job file may even have several +*global* sections if so desired. A job is only affected by a *global* section +residing above it. + +The :option:`--cmdhelp` option also lists all options. If used with an `option` +argument, :option:`--cmdhelp` will detail the given `option`. + +See the `examples/` directory for inspiration on how to write job files. Note +the copyright and license requirements currently apply to `examples/` files. + +So let's look at a really simple job file that defines two processes, each +randomly reading from a 128MiB file: + +.. code-block:: ini + + ; -- start job file -- + [global] + rw=randread + size=128m + + [job1] + + [job2] + + ; -- end job file -- + +As you can see, the job file sections themselves are empty as all the described +parameters are shared. As no :option:`filename` option is given, fio makes up a +`filename` for each of the jobs as it sees fit. On the command line, this job +would look as follows:: + +$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2 + + +Let's look at an example that has a number of processes writing randomly to +files: + +.. code-block:: ini + + ; -- start job file -- + [random-writers] + ioengine=libaio + iodepth=4 + rw=randwrite + bs=32k + direct=0 + size=64m + numjobs=4 + ; -- end job file -- + +Here we have no *global* section, as we only have one job defined anyway. We +want to use async I/O here, with a depth of 4 for each file. We also increased +the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical +jobs. The result is 4 processes each randomly writing to their own 64MiB +file. Instead of using the above job file, you could have given the parameters +on the command line. For this case, you would specify:: + +$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4 + +When fio is utilized as a basis of any reasonably large test suite, it might be +desirable to share a set of standardized settings across multiple job files. +Instead of copy/pasting such settings, any section may pull in an external +:file:`filename.fio` file with *include filename* directive, as in the following +example:: + + ; -- start job file including.fio -- + [global] + filename=/tmp/test + filesize=1m + include glob-include.fio + + [test] + rw=randread + bs=4k + time_based=1 + runtime=10 + include test-include.fio + ; -- end job file including.fio -- + +.. code-block:: ini + + ; -- start job file glob-include.fio -- + thread=1 + group_reporting=1 + ; -- end job file glob-include.fio -- + +.. code-block:: ini + + ; -- start job file test-include.fio -- + ioengine=libaio + iodepth=4 + ; -- end job file test-include.fio -- + +Settings pulled into a section apply to that section only (except *global* +section). Include directives may be nested in that any included file may contain +further include directive(s). Include files may not contain [] sections. + + +Environment variables +~~~~~~~~~~~~~~~~~~~~~ + +Fio also supports environment variable expansion in job files. Any sub-string of +the form ``${VARNAME}`` as part of an option value (in other words, on the right +of the '='), will be expanded to the value of the environment variable called +`VARNAME`. If no such environment variable is defined, or `VARNAME` is the +empty string, the empty string will be substituted. + +As an example, let's look at a sample fio invocation and job file:: + +$ SIZE=64m NUMJOBS=4 fio jobfile.fio + +.. code-block:: ini + + ; -- start job file -- + [random-writers] + rw=randwrite + size=${SIZE} + numjobs=${NUMJOBS} + ; -- end job file -- + +This will expand to the following equivalent job file at runtime: + +.. code-block:: ini + + ; -- start job file -- + [random-writers] + rw=randwrite + size=64m + numjobs=4 + ; -- end job file -- + +Fio ships with a few example job files, you can also look there for inspiration. + +Reserved keywords +~~~~~~~~~~~~~~~~~ + +Additionally, fio has a set of reserved keywords that will be replaced +internally with the appropriate value. Those keywords are: + +**$pagesize** + + The architecture page size of the running system. + +**$mb_memory** + + Megabytes of total memory in the system. + +**$ncpus** + + Number of online available CPUs. + +These can be used on the command line or in the job file, and will be +automatically substituted with the current system values when the job is +run. Simple math is also supported on these keywords, so you can perform actions +like:: + + size=8*$mb_memory + +and get that properly expanded to 8 times the size of memory in the machine. + + +Job file parameters +------------------- + +This section describes in details each parameter associated with a job. Some +parameters take an option of a given type, such as an integer or a +string. Anywhere a numeric value is required, an arithmetic expression may be +used, provided it is surrounded by parentheses. Supported operators are: + + - addition (+) + - subtraction (-) + - multiplication (*) + - division (/) + - modulus (%) + - exponentiation (^) + +For time values in expressions, units are microseconds by default. This is +different than for time values not in expressions (not enclosed in +parentheses). The following types are used: + + +Parameter types +~~~~~~~~~~~~~~~ + +**str** + String. This is a sequence of alpha characters. + +**time** + Integer with possible time suffix. In seconds unless otherwise + specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds, minutes, + and hours, and accepts 'ms' (or 'msec') for milliseconds, and 'us' (or + 'usec') for microseconds. + +.. _int: + +**int** + Integer. A whole number value, which may contain an integer prefix + and an integer suffix: + + [*integer prefix*] **number** [*integer suffix*] + + The optional *integer prefix* specifies the number's base. The default + is decimal. *0x* specifies hexadecimal. + + The optional *integer suffix* specifies the number's units, and includes an + optional unit prefix and an optional unit. For quantities of data, the + default unit is bytes. For quantities of time, the default unit is seconds. + + With :option:`kb_base` =1000, fio follows international standards for unit + prefixes. To specify power-of-10 decimal values defined in the + International System of Units (SI): + + * *Ki* -- means kilo (K) or 1000 + * *Mi* -- means mega (M) or 1000**2 + * *Gi* -- means giga (G) or 1000**3 + * *Ti* -- means tera (T) or 1000**4 + * *Pi* -- means peta (P) or 1000**5 + + To specify power-of-2 binary values defined in IEC 80000-13: + + * *k* -- means kibi (Ki) or 1024 + * *M* -- means mebi (Mi) or 1024**2 + * *G* -- means gibi (Gi) or 1024**3 + * *T* -- means tebi (Ti) or 1024**4 + * *P* -- means pebi (Pi) or 1024**5 + + With :option:`kb_base` =1024 (the default), the unit prefixes are opposite + from those specified in the SI and IEC 80000-13 standards to provide + compatibility with old scripts. For example, 4k means 4096. + + For quantities of data, an optional unit of 'B' may be included + (e.g., 'kB' is the same as 'k'). + + The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega, + not milli). 'b' and 'B' both mean byte, not bit. + + Examples with :option:`kb_base` =1000: + + * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB + * *1 MiB*: 1048576, 1mi, 1024ki + * *1 MB*: 1000000, 1m, 1000k + * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi + * *1 TB*: 1000000000, 1t, 1000m, 1000000k + + Examples with :option:`kb_base` =1024 (default): + + * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB + * *1 MiB*: 1048576, 1m, 1024k + * *1 MB*: 1000000, 1mi, 1000ki + * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m + * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki + + To specify times (units are not case sensitive): + + * *D* -- means days + * *H* -- means hours + * *M* -- mean minutes + * *s* -- or sec means seconds (default) + * *ms* -- or *msec* means milliseconds + * *us* -- or *usec* means microseconds + + If the option accepts an upper and lower range, use a colon ':' or + minus '-' to separate such values. See :ref:`irange `. + +.. _bool: + +**bool** + Boolean. Usually parsed as an integer, however only defined for + true and false (1 and 0). + +.. _irange: + +**irange** + Integer range with suffix. Allows value range to be given, such as + 1024-4096. A colon may also be used as the separator, eg 1k:4k. If the + option allows two sets of ranges, they can be specified with a ',' or '/' + delimiter: 1k-4k/8k-32k. Also see :ref:`int `. + +**float_list** + A list of floating point numbers, separated by a ':' character. + + +Units +~~~~~ + +.. option:: kb_base=int + + Select the interpretation of unit prefixes in input parameters. + + **1000** + Inputs comply with IEC 80000-13 and the International + System of Units (SI). Use: + + - power-of-2 values with IEC prefixes (e.g., KiB) + - power-of-10 values with SI prefixes (e.g., kB) + + **1024** + Compatibility mode (default). To avoid breaking old scripts: + + - power-of-2 values with SI prefixes + - power-of-10 values with IEC prefixes + + See :option:`bs` for more details on input parameters. + + Outputs always use correct prefixes. Most outputs include both + side-by-side, like:: + + bw=2383.3kB/s (2327.4KiB/s) + + If only one value is reported, then kb_base selects the one to use: + + **1000** -- SI prefixes + + **1024** -- IEC prefixes + +.. option:: unit_base=int + + Base unit for reporting. Allowed values are: + + **0** + Use auto-detection (default). + **8** + Byte based. + **1** + Bit based. + + +With the above in mind, here follows the complete list of fio job parameters. + + +Job description +~~~~~~~~~~~~~~~ + +.. option:: name=str + + ASCII name of the job. This may be used to override the name printed by fio + for this job. Otherwise the job name is used. On the command line this + parameter has the special purpose of also signaling the start of a new job. + +.. option:: description=str + + Text description of the job. Doesn't do anything except dump this text + description when this job is run. It's not parsed. + +.. option:: loops=int + + Run the specified number of iterations of this job. Used to repeat the same + workload a given number of times. Defaults to 1. + +.. option:: numjobs=int + + Create the specified number of clones of this job. May be used to setup a + larger number of threads/processes doing the same thing. Each thread is + reported separately; to see statistics for all clones as a whole, use + :option:`group_reporting` in conjunction with :option:`new_group`. + See :option:`--max-jobs`. + + +Time related parameters +~~~~~~~~~~~~~~~~~~~~~~~ + +.. option:: runtime=time + + Tell fio to terminate processing after the specified number of seconds. It + can be quite hard to determine for how long a specified job will run, so + this parameter is handy to cap the total runtime to a given time. + +.. option:: time_based + + If set, fio will run for the duration of the :option:`runtime` specified + even if the file(s) are completely read or written. It will simply loop over + the same workload as many times as the :option:`runtime` allows. + +.. option:: startdelay=irange + + Delay start of job for the specified number of seconds. Supports all time + suffixes to allow specification of hours, minutes, seconds and milliseconds + -- seconds are the default if a unit is omitted. Can be given as a range + which causes each thread to choose randomly out of the range. + +.. option:: ramp_time=time + + If set, fio will run the specified workload for this amount of time before + logging any performance numbers. Useful for letting performance settle + before logging results, thus minimizing the runtime required for stable + results. Note that the ``ramp_time`` is considered lead in time for a job, + thus it will increase the total runtime if a special timeout or + :option:`runtime` is specified. + +.. option:: clocksource=str + + Use the given clocksource as the base of timing. The supported options are: + + **gettimeofday** + :manpage:`gettimeofday(2)` + + **clock_gettime** + :manpage:`clock_gettime(2)` + + **cpu** + Internal CPU clock source + + cpu is the preferred clocksource if it is reliable, as it is very fast (and + fio is heavy on time calls). Fio will automatically use this clocksource if + it's supported and considered reliable on the system it is running on, + unless another clocksource is specifically set. For x86/x86-64 CPUs, this + means supporting TSC Invariant. + +.. option:: gtod_reduce=bool + + Enable all of the :manpage:`gettimeofday(2)` reducing options + (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw`) plus + reduce precision of the timeout somewhat to really shrink the + :manpage:`gettimeofday(2)` call count. With this option enabled, we only do + about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all + time keeping was enabled. + +.. option:: gtod_cpu=int + + Sometimes it's cheaper to dedicate a single thread of execution to just + getting the current time. Fio (and databases, for instance) are very + intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set + one CPU aside for doing nothing but logging current time to a shared memory + location. Then the other threads/processes that run I/O workloads need only + copy that segment, instead of entering the kernel with a + :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time + calls will be excluded from other uses. Fio will manually clear it from the + CPU mask of other jobs. + + +Target file/device +~~~~~~~~~~~~~~~~~~ + +.. option:: directory=str + + Prefix filenames with this directory. Used to place files in a different + location than :file:`./`. You can specify a number of directories by + separating the names with a ':' character. These directories will be + assigned equally distributed to job clones creates with :option:`numjobs` as + long as they are using generated filenames. If specific `filename(s)` are + set fio will use the first listed directory, and thereby matching the + `filename` semantic which generates a file each clone if not specified, but + let all clones use the same if set. + + See the :option:`filename` option for escaping certain characters. + +.. option:: filename=str + + Fio normally makes up a `filename` based on the job name, thread number, and + file number. If you want to share files between threads in a job or several + jobs, specify a `filename` for each of them to override the default. If the + ioengine is file based, you can specify a number of files by separating the + names with a ':' colon. So if you wanted a job to open :file:`/dev/sda` and + :file:`/dev/sdb` as the two working files, you would use + ``filename=/dev/sda:/dev/sdb``. + On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for + the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc. + Note: Windows and FreeBSD prevent write access to areas + of the disk containing in-use data (e.g. filesystems). If the wanted + `filename` does need to include a colon, then escape that with a ``\`` + character. For instance, if the `filename` is :file:`/dev/dsk/foo@3,0:c`, + then you would use ``filename="/dev/dsk/foo@3,0\:c"``. The + :file:`-` is a reserved name, meaning stdin or stdout. Which of the two + depends on the read/write direction set. + +.. option:: filename_format=str + + If sharing multiple files between jobs, it is usually necessary to have fio + generate the exact names that you want. By default, fio will name a file + based on the default file format specification of + :file:`jobname.jobnumber.filenumber`. With this option, that can be + customized. Fio will recognize and replace the following keywords in this + string: + + **$jobname** + The name of the worker thread or process. + **$jobnum** + The incremental number of the worker thread or process. + **$filenum** + The incremental number of the file for that worker thread or + process. + + To have dependent jobs share a set of files, this option can be set to have + fio generate filenames that are shared between the two. For instance, if + :file:`testfiles.$filenum` is specified, file number 4 for any job will be + named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum` + will be used if no other format specifier is given. + +.. option:: unique_filename=bool + + To avoid collisions between networked clients, fio defaults to prefixing any + generated filenames (with a directory specified) with the source of the + client connecting. To disable this behavior, set this option to 0. + +.. option:: opendir=str + + Recursively open any files below directory `str`. + +.. option:: lockfile=str + + Fio defaults to not locking any files before it does I/O to them. If a file + or file descriptor is shared, fio can serialize I/O to that file to make the + end result consistent. This is usual for emulating real workloads that share + files. The lock modes are: + + **none** + No locking. The default. + **exclusive** + Only one thread or process may do I/O at a time, excluding all + others. + **readwrite** + Read-write locking on the file. Many readers may + access the file at the same time, but writes get exclusive access. + +.. option:: nrfiles=int + + Number of files to use for this job. Defaults to 1. + +.. option:: openfiles=int + + Number of files to keep open at the same time. Defaults to the same as + :option:`nrfiles`, can be set smaller to limit the number simultaneous + opens. + +.. option:: file_service_type=str + + Defines how fio decides which file from a job to service next. The following + types are defined: + + **random** + Choose a file at random. + + **roundrobin** + Round robin over opened files. This is the default. + + **sequential** + Finish one file before moving on to the next. Multiple files can + still be open depending on 'openfiles'. + + **zipf** + Use a *zipfian* distribution to decide what file to access. + + **pareto** + Use a *pareto* distribution to decide what file to access. + + **gauss** + Use a *gaussian* (normal) distribution to decide what file to + access. + + For *random*, *roundrobin*, and *sequential*, a postfix can be appended to + tell fio how many I/Os to issue before switching to a new file. For example, + specifying ``file_service_type=random:8`` would cause fio to issue + 8 I/Os before selecting a new file at random. For the non-uniform + distributions, a floating point postfix can be given to influence how the + distribution is skewed. See :option:`random_distribution` for a description + of how that would work. + +.. option:: ioscheduler=str + + Attempt to switch the device hosting the file to the specified I/O scheduler + before running. + +.. option:: create_serialize=bool + + If true, serialize the file creation for the jobs. This may be handy to + avoid interleaving of data files, which may greatly depend on the filesystem + used and even the number of processors in the system. + +.. option:: create_fsync=bool + + fsync the data file after creation. This is the default. + +.. option:: create_on_open=bool + + Don't pre-setup the files for I/O, just create open() when it's time to do + I/O to that file. + +.. option:: create_only=bool + + If true, fio will only run the setup phase of the job. If files need to be + laid out or updated on disk, only that will be done. The actual job contents + are not executed. + +.. option:: allow_file_create=bool + + If true, fio is permitted to create files as part of its workload. This is + the default behavior. If this option is false, then fio will error out if + the files it needs to use don't already exist. Default: true. + +.. option:: allow_mounted_write=bool + + If this isn't set, fio will abort jobs that are destructive (eg that write) + to what appears to be a mounted device or partition. This should help catch + creating inadvertently destructive tests, not realizing that the test will + destroy data on the mounted file system. Default: false. + +.. option:: pre_read=bool + + If this is given, files will be pre-read into memory before starting the + given I/O operation. This will also clear the :option:`invalidate` flag, + since it is pointless to pre-read and then drop the cache. This will only + work for I/O engines that are seek-able, since they allow you to read the + same data multiple times. Thus it will not work on eg network or splice I/O. + +.. option:: unlink=bool + + Unlink the job files when done. Not the default, as repeated runs of that + job would then waste time recreating the file set again and again. + +.. option:: unlink_each_loop=bool + + Unlink job files after each iteration or loop. + +.. option:: zonesize=int + + Divide a file into zones of the specified size. See :option:`zoneskip`. + +.. option:: zonerange=int + + Give size of an I/O zone. See :option:`zoneskip`. + +.. option:: zoneskip=int + + Skip the specified number of bytes when :option:`zonesize` data has been + read. The two zone options can be used to only do I/O on zones of a file. + + +I/O type +~~~~~~~~ + +.. option:: direct=bool + + If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that + ZFS on Solaris doesn't support direct I/O. On Windows the synchronous + ioengines don't support direct I/O. Default: false. + +.. option:: atomic=bool + + If value is true, attempt to use atomic direct I/O. Atomic writes are + guaranteed to be stable once acknowledged by the operating system. Only + Linux supports O_ATOMIC right now. + +.. option:: buffered=bool + + If value is true, use buffered I/O. This is the opposite of the + :option:`direct` option. Defaults to true. + +.. option:: readwrite=str, rw=str + + Type of I/O pattern. Accepted values are: + + **read** + Sequential reads. + **write** + Sequential writes. + **trim** + Sequential trims (Linux block devices only). + **randwrite** + Random writes. + **randread** + Random reads. + **randtrim** + Random trims (Linux block devices only). + **rw,readwrite** + Sequential mixed reads and writes. + **randrw** + Random mixed reads and writes. + **trimwrite** + Sequential trim+write sequences. Blocks will be trimmed first, + then the same blocks will be written to. + + Fio defaults to read if the option is not specified. For the mixed I/O + types, the default is to split them 50/50. For certain types of I/O the + result may still be skewed a bit, since the speed may be different. It is + possible to specify a number of I/O's to do before getting a new offset, + this is done by appending a ``:`` to the end of the string given. For a + random read, it would look like ``rw=randread:8`` for passing in an offset + modifier with a value of 8. If the suffix is used with a sequential I/O + pattern, then the value specified will be added to the generated offset for + each I/O. For instance, using ``rw=write:4k`` will skip 4k for every + write. It turns sequential I/O into sequential I/O with holes. See the + :option:`rw_sequencer` option. + +.. option:: rw_sequencer=str + + If an offset modifier is given by appending a number to the ``rw=`` + line, then this option controls how that number modifies the I/O offset + being generated. Accepted values are: + + **sequential** + Generate sequential offset. + **identical** + Generate the same offset. + + ``sequential`` is only useful for random I/O, where fio would normally + generate a new random offset for every I/O. If you append eg 8 to randread, + you would get a new random offset for every 8 I/O's. The result would be a + seek for only every 8 I/O's, instead of for every I/O. Use ``rw=randread:8`` + to specify that. As sequential I/O is already sequential, setting + ``sequential`` for that would not result in any differences. ``identical`` + behaves in a similar fashion, except it sends the same offset 8 number of + times before generating a new offset. + +.. option:: unified_rw_reporting=bool + + Fio normally reports statistics on a per data direction basis, meaning that + reads, writes, and trims are accounted and reported separately. If this + option is set fio sums the results and report them as "mixed" instead. + +.. option:: randrepeat=bool + + Seed the random number generator used for random I/O patterns in a + predictable way so the pattern is repeatable across runs. Default: true. + +.. option:: allrandrepeat=bool + + Seed all random number generators in a predictable way so results are + repeatable across runs. Default: false. + +.. option:: randseed=int + + Seed the random number generators based on this seed value, to be able to + control what sequence of output is being generated. If not set, the random + sequence depends on the :option:`randrepeat` setting. + +.. option:: fallocate=str + + Whether pre-allocation is performed when laying down files. + Accepted values are: + + **none** + Do not pre-allocate space. + + **posix** + Pre-allocate via :manpage:`posix_fallocate(3)`. + + **keep** + Pre-allocate via :manpage:`fallocate(2)` with + FALLOC_FL_KEEP_SIZE set. + + **0** + Backward-compatible alias for **none**. + + **1** + Backward-compatible alias for **posix**. + + May not be available on all supported platforms. **keep** is only available + on Linux. If using ZFS on Solaris this must be set to **none** because ZFS + doesn't support it. Default: **posix**. + +.. option:: fadvise_hint=str + + Use :manpage:`posix_fadvise(2)` to advise the kernel on what I/O patterns + are likely to be issued. Accepted values are: + + **0** + Backwards-compatible hint for "no hint". + + **1** + Backwards compatible hint for "advise with fio workload type". This + uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL** + for a sequential workload. + + **sequential** + Advise using **FADV_SEQUENTIAL**. + + **random** + Advise using **FADV_RANDOM**. + +.. option:: fadvise_stream=int + + Use :manpage:`posix_fadvise(2)` to advise the kernel what stream ID the + writes issued belong to. Only supported on Linux. Note, this option may + change going forward. + +.. option:: offset=int + + Start I/O at the given offset in the file. The data before the given offset + will not be touched. This effectively caps the file size at `real_size - + offset`. + +.. option:: offset_increment=int + + If this is provided, then the real offset becomes `offset + offset_increment + * thread_number`, where the thread number is a counter that starts at 0 and + is incremented for each sub-job (i.e. when :option:`numjobs` option is + specified). This option is useful if there are several jobs which are + intended to operate on a file in parallel disjoint segments, with even + spacing between the starting points. + +.. option:: number_ios=int + + Fio will normally perform IOs until it has exhausted the size of the region + set by :option:`size`, or if it exhaust the allocated time (or hits an error + condition). With this setting, the range/size can be set independently of + the number of IOs to perform. When fio reaches this number, it will exit + normally and report status. Note that this does not extend the amount of I/O + that will be done, it will only stop fio if this condition is met before + other end-of-job criteria. + +.. option:: fsync=int + + If writing to a file, issue a sync of the dirty data for every number of + blocks given. For example, if you give 32 as a parameter, fio will sync the + file for every 32 writes issued. If fio is using non-buffered I/O, we may + not sync the file. The exception is the sg I/O engine, which synchronizes + the disk cache anyway. + +.. option:: fdatasync=int + + Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and + not metadata blocks. In FreeBSD and Windows there is no + :manpage:`fdatasync(2)`, this falls back to using :manpage:`fsync(2)`. + +.. option:: write_barrier=int + + Make every `N-th` write a barrier write. + +.. option:: sync_file_range=str:val + + Use :manpage:`sync_file_range(2)` for every `val` number of write + operations. Fio will track range of writes that have happened since the last + :manpage:`sync_file_range(2)` call. `str` can currently be one or more of: + + **wait_before** + SYNC_FILE_RANGE_WAIT_BEFORE + **write** + SYNC_FILE_RANGE_WRITE + **wait_after** + SYNC_FILE_RANGE_WAIT_AFTER + + So if you do ``sync_file_range=wait_before,write:8``, fio would use + ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8 + writes. Also see the :manpage:`sync_file_range(2)` man page. This option is + Linux specific. + +.. option:: overwrite=bool + + If true, writes to a file will always overwrite existing data. If the file + doesn't already exist, it will be created before the write phase begins. If + the file exists and is large enough for the specified write phase, nothing + will be done. + +.. option:: end_fsync=bool + + If true, fsync file contents when a write stage has completed. + +.. option:: fsync_on_close=bool + + If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs + from end_fsync in that it will happen on every file close, not just at the + end of the job. + +.. option:: rwmixread=int + + Percentage of a mixed workload that should be reads. Default: 50. + +.. option:: rwmixwrite=int + + Percentage of a mixed workload that should be writes. If both + :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not + add up to 100%, the latter of the two will be used to override the + first. This may interfere with a given rate setting, if fio is asked to + limit reads or writes to a certain rate. If that is the case, then the + distribution may be skewed. Default: 50. + +.. option:: random_distribution=str:float[,str:float][,str:float] + + By default, fio will use a completely uniform random distribution when asked + to perform random I/O. Sometimes it is useful to skew the distribution in + specific ways, ensuring that some parts of the data is more hot than others. + fio includes the following distribution models: + + **random** + Uniform random distribution + + **zipf** + Zipf distribution + + **pareto** + Pareto distribution + + **gauss** + Normal (gaussian) distribution + + **zoned** + Zoned random distribution + + When using a **zipf** or **pareto** distribution, an input value is also + needed to define the access pattern. For **zipf**, this is the `zipf + theta`. For **pareto**, it's the `pareto power`. Fio includes a test + program, :command:`genzipf`, that can be used visualize what the given input + values will yield in terms of hit rates. If you wanted to use **zipf** with + a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the + option. If a non-uniform model is used, fio will disable use of the random + map. For the **gauss** distribution, a normal deviation is supplied as a + value between 0 and 100. + + For a **zoned** distribution, fio supports specifying percentages of I/O + access that should fall within what range of the file or device. For + example, given a criteria of: + + * 60% of accesses should be to the first 10% + * 30% of accesses should be to the next 20% + * 8% of accesses should be to to the next 30% + * 2% of accesses should be to the next 40% + + we can define that through zoning of the random accesses. For the above + example, the user would do:: + + random_distribution=zoned:60/10:30/20:8/30:2/40 + + similarly to how :option:`bssplit` works for setting ranges and percentages + of block sizes. Like :option:`bssplit`, it's possible to specify separate + zones for reads, writes, and trims. If just one set is given, it'll apply to + all of them. + +.. option:: percentage_random=int[,int][,int] + + For a random workload, set how big a percentage should be random. This + defaults to 100%, in which case the workload is fully random. It can be set + from anywhere from 0 to 100. Setting it to 0 would make the workload fully + sequential. Any setting in between will result in a random mix of sequential + and random I/O, at the given percentages. Comma-separated values may be + specified for reads, writes, and trims as described in :option:`blocksize`. + +.. option:: norandommap + + Normally fio will cover every block of the file when doing random I/O. If + this option is given, fio will just get a new random offset without looking + at past I/O history. This means that some blocks may not be read or written, + and that some blocks may be read/written more than once. If this option is + used with :option:`verify` and multiple blocksizes (via :option:`bsrange`), + only intact blocks are verified, i.e., partially-overwritten blocks are + ignored. + +.. option:: softrandommap=bool + + See :option:`norandommap`. If fio runs with the random block map enabled and + it fails to allocate the map, if this option is set it will continue without + a random block map. As coverage will not be as complete as with random maps, + this option is disabled by default. + +.. option:: random_generator=str + + Fio supports the following engines for generating + I/O offsets for random I/O: + + **tausworthe** + Strong 2^88 cycle random number generator + **lfsr** + Linear feedback shift register generator + **tausworthe64** + Strong 64-bit 2^258 cycle random number generator + + **tausworthe** is a strong random number generator, but it requires tracking + on the side if we want to ensure that blocks are only read or written + once. **LFSR** guarantees that we never generate the same offset twice, and + it's also less computationally expensive. It's not a true random generator, + however, though for I/O purposes it's typically good enough. **LFSR** only + works with single block sizes, not with workloads that use multiple block + sizes. If used with such a workload, fio may read or write some blocks + multiple times. The default value is **tausworthe**, unless the required + space exceeds 2^32 blocks. If it does, then **tausworthe64** is + selected automatically. + + +Block size +~~~~~~~~~~ + +.. option:: blocksize=int[,int][,int], bs=int[,int][,int] + + The block size in bytes used for I/O units. Default: 4096. A single value + applies to reads, writes, and trims. Comma-separated values may be + specified for reads, writes, and trims. A value not terminated in a comma + applies to subsequent types. + + Examples: + + **bs=256k** + means 256k for reads, writes and trims. + + **bs=8k,32k** + means 8k for reads, 32k for writes and trims. + + **bs=8k,32k,** + means 8k for reads, 32k for writes, and default for trims. + + **bs=,8k** + means default for reads, 8k for writes and trims. + + **bs=,8k,** + means default for reads, 8k for writes, and default for writes. + +.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange] + + A range of block sizes in bytes for I/O units. The issued I/O unit will + always be a multiple of the minimum size, unless + :option:`blocksize_unaligned` is set. + + Comma-separated ranges may be specified for reads, writes, and trims as + described in :option:`blocksize`. + + Example: ``bsrange=1k-4k,2k-8k``. + +.. option:: bssplit=str[,str][,str] + + Sometimes you want even finer grained control of the block sizes issued, not + just an even split between them. This option allows you to weight various + block sizes, so that you are able to define a specific amount of block sizes + issued. The format for this option is:: + + bssplit=blocksize/percentage:blocksize/percentage + + for as many block sizes as needed. So if you want to define a workload that + has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would write:: + + bssplit=4k/10:64k/50:32k/40 + + Ordering does not matter. If the percentage is left blank, fio will fill in + the remaining values evenly. So a bssplit option like this one:: + + bssplit=4k/50:1k/:32k/ + + would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always add up + to 100, if bssplit is given a range that adds up to more, it will error out. + + Comma-separated values may be specified for reads, writes, and trims as + described in :option:`blocksize`. + + If you want a workload that has 50% 2k reads and 50% 4k reads, while having + 90% 4k writes and 10% 8k writes, you would specify:: + + bssplit=2k/50:4k/50,4k/90,8k/10 + +.. option:: blocksize_unaligned, bs_unaligned + + If set, fio will issue I/O units with any size within + :option:`blocksize_range`, not just multiples of the minimum size. This + typically won't work with direct I/O, as that normally requires sector + alignment. + +.. option:: bs_is_seq_rand + + If this option is set, fio will use the normal read,write blocksize settings + as sequential,random blocksize settings instead. Any random read or write + will use the WRITE blocksize settings, and any sequential read or write will + use the READ blocksize settings. + +.. option:: blockalign=int[,int][,int], ba=int[,int][,int] + + Boundary to which fio will align random I/O units. Default: + :option:`blocksize`. Minimum alignment is typically 512b for using direct + I/O, though it usually depends on the hardware block size. This option is + mutually exclusive with using a random map for files, so it will turn off + that option. Comma-separated values may be specified for reads, writes, and + trims as described in :option:`blocksize`. + + +Buffers and memory +~~~~~~~~~~~~~~~~~~ + +.. option:: zero_buffers + + Initialize buffers with all zeros. Default: fill buffers with random data. + +.. option:: refill_buffers + + If this option is given, fio will refill the I/O buffers on every + submit. The default is to only fill it at init time and reuse that + data. Only makes sense if zero_buffers isn't specified, naturally. If data + verification is enabled, `refill_buffers` is also automatically enabled. + +.. option:: scramble_buffers=bool + + If :option:`refill_buffers` is too costly and the target is using data + deduplication, then setting this option will slightly modify the I/O buffer + contents to defeat normal de-dupe attempts. This is not enough to defeat + more clever block compression attempts, but it will stop naive dedupe of + blocks. Default: true. + +.. option:: buffer_compress_percentage=int + + If this is set, then fio will attempt to provide I/O buffer content (on + WRITEs) that compress to the specified level. Fio does this by providing a + mix of random data and a fixed pattern. The fixed pattern is either zeroes, + or the pattern specified by :option:`buffer_pattern`. If the pattern option + is used, it might skew the compression ratio slightly. Note that this is per + block size unit, for file/disk wide compression level that matches this + setting, you'll also want to set :option:`refill_buffers`. + +.. option:: buffer_compress_chunk=int + + See :option:`buffer_compress_percentage`. This setting allows fio to manage + how big the ranges of random data and zeroed data is. Without this set, fio + will provide :option:`buffer_compress_percentage` of blocksize random data, + followed by the remaining zeroed. With this set to some chunk size smaller + than the block size, fio can alternate random and zeroed data throughout the + I/O buffer. + +.. option:: buffer_pattern=str + + If set, fio will fill the I/O buffers with this pattern. If not set, the + contents of I/O buffers is defined by the other options related to buffer + contents. The setting can be any pattern of bytes, and can be prefixed with + 0x for hex values. It may also be a string, where the string must then be + wrapped with ``""``, e.g.:: + + buffer_pattern="abcd" + + or:: + + buffer_pattern=-12 + + or:: + + buffer_pattern=0xdeadface + + Also you can combine everything together in any order:: + + buffer_pattern=0xdeadface"abcd"-12 + +.. option:: dedupe_percentage=int + + If set, fio will generate this percentage of identical buffers when + writing. These buffers will be naturally dedupable. The contents of the + buffers depend on what other buffer compression settings have been set. It's + possible to have the individual buffers either fully compressible, or not at + all. This option only controls the distribution of unique buffers. + +.. option:: invalidate=bool + + Invalidate the buffer/page cache parts for this file prior to starting + I/O. Defaults to true. + +.. option:: sync=bool + + Use synchronous I/O for buffered writes. For the majority of I/O engines, + this means using O_SYNC. Default: false. + +.. option:: iomem=str, mem=str + + Fio can use various types of memory as the I/O unit buffer. The allowed + values are: + + **malloc** + Use memory from :manpage:`malloc(3)` as the buffers. Default memory + type. + + **shm** + Use shared memory as the buffers. Allocated through + :manpage:`shmget(2)`. + + **shmhuge** + Same as shm, but use huge pages as backing. + + **mmap** + Use mmap to allocate buffers. May either be anonymous memory, or can + be file backed if a filename is given after the option. The format + is `mem=mmap:/path/to/file`. + + **mmaphuge** + Use a memory mapped huge file as the buffer backing. Append filename + after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`. + + **mmapshared** + Same as mmap, but use a MMAP_SHARED mapping. + + The area allocated is a function of the maximum allowed bs size for the job, + multiplied by the I/O depth given. Note that for **shmhuge** and + **mmaphuge** to work, the system must have free huge pages allocated. This + can normally be checked and set by reading/writing + :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page + is 4MiB in size. So to calculate the number of huge pages you need for a + given job file, add up the I/O depth of all jobs (normally one unless + :option:`iodepth` is used) and multiply by the maximum bs set. Then divide + that number by the huge page size. You can see the size of the huge pages in + :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero + number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also + see :option:`hugepage-size`. + + **mmaphuge** also needs to have hugetlbfs mounted and the file location + should point there. So if it's mounted in :file:`/huge`, you would use + `mem=mmaphuge:/huge/somefile`. + +.. option:: iomem_align=int + + This indicates the memory alignment of the I/O memory buffers. Note that + the given alignment is applied to the first I/O unit buffer, if using + :option:`iodepth` the alignment of the following buffers are given by the + :option:`bs` used. In other words, if using a :option:`bs` that is a + multiple of the page sized in the system, all buffers will be aligned to + this value. If using a :option:`bs` that is not page aligned, the alignment + of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and + :option:`bs` used. + +.. option:: hugepage-size=int + + Defines the size of a huge page. Must at least be equal to the system + setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably + always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the + preferred way to set this to avoid setting a non-pow-2 bad value. + +.. option:: lockmem=int + + Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to + simulate a smaller amount of memory. The amount specified is per worker. + + +I/O size +~~~~~~~~ + +.. option:: size=int + + The total size of file I/O for this job. Fio will run until this many bytes + has been transferred, unless runtime is limited by other options (such as + :option:`runtime`, for instance, or increased/decreased by + :option:`io_size`). Unless specific :option:`nrfiles` and :option:`filesize` + options are given, fio will divide this size between the available files + specified by the job. If not set, fio will use the full size of the given + files or devices. If the files do not exist, size must be given. It is also + possible to give size as a percentage between 1 and 100. If ``size=20%`` is + given, fio will use 20% of the full size of the given files or devices. + +.. option:: io_size=int, io_limit=int + + Normally fio operates within the region set by :option:`size`, which means + that the :option:`size` option sets both the region and size of I/O to be + performed. Sometimes that is not what you want. With this option, it is + possible to define just the amount of I/O that fio should do. For instance, + if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio + will perform I/O within the first 20GiB but exit when 5GiB have been + done. The opposite is also possible -- if :option:`size` is set to 20GiB, + and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within + the 0..20GiB region. + +.. option:: filesize=int + + Individual file sizes. May be a range, in which case fio will select sizes + for files at random within the given range and limited to :option:`size` in + total (if that is given). If not given, each created file is the same size. + +.. option:: file_append=bool + + Perform I/O after the end of the file. Normally fio will operate within the + size of a file. If this option is set, then fio will append to the file + instead. This has identical behavior to setting :option:`offset` to the size + of a file. This option is ignored on non-regular files. + +.. option:: fill_device=bool, fill_fs=bool + + Sets size to something really large and waits for ENOSPC (no space left on + device) as the terminating condition. Only makes sense with sequential + write. For a read workload, the mount point will be filled first then I/O + started on the result. This option doesn't make sense if operating on a raw + device node, since the size of that is already known by the file system. + Additionally, writing beyond end-of-device will not return ENOSPC there. + + +I/O engine +~~~~~~~~~~ + +.. option:: ioengine=str + + Defines how the job issues I/O to the file. The following types are defined: + + **sync** + Basic :manpage:`read(2)` or :manpage:`write(2)` + I/O. :manpage:`lseek(2)` is used to position the I/O location. + + **psync** + Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on + all supported operating systems except for Windows. + + **vsync** + Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate + queuing by coalescing adjacent IOs into a single submission. + + **pvsync** + Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O. + + **pvsync2** + Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O. + + **libaio** + Linux native asynchronous I/O. Note that Linux may only support + queued behaviour with non-buffered I/O (set ``direct=1`` or + ``buffered=0``). + This engine defines engine specific options. + + **posixaio** + POSIX asynchronous I/O using :manpage:`aio_read(3)` and + :manpage:`aio_write(3)`. + + **solarisaio** + Solaris native asynchronous I/O. + + **windowsaio** + Windows native asynchronous I/O. Default on Windows. + + **mmap** + File is memory mapped with :manpage:`mmap(2)` and data copied + to/from using :manpage:`memcpy(3)`. + + **splice** + :manpage:`splice(2)` is used to transfer the data and + :manpage:`vmsplice(2)` to transfer data from user space to the + kernel. + + **sg** + SCSI generic sg v3 I/O. May either be synchronous using the SG_IO + ioctl, or if the target is an sg character device we use + :manpage:`read(2)` and :manpage:`write(2)` for asynchronous + I/O. Requires filename option to specify either block or character + devices. + + **null** + Doesn't transfer any data, just pretends to. This is mainly used to + exercise fio itself and for debugging/testing purposes. + + **net** + Transfer over the network to given ``host:port``. Depending on the + :option:`protocol` used, the :option:`hostname`, :option:`port`, + :option:`listen` and :option:`filename` options are used to specify + what sort of connection to make, while the :option:`protocol` option + determines which protocol will be used. This engine defines engine + specific options. + + **netsplice** + Like **net**, but uses :manpage:`splice(2)` and + :manpage:`vmsplice(2)` to map data and send/receive. + This engine defines engine specific options. + + **cpuio** + Doesn't transfer any data, but burns CPU cycles according to the + :option:`cpuload` and :option:`cpuchunks` options. Setting + :option:`cpuload` =85 will cause that job to do nothing but burn 85% + of the CPU. In case of SMP machines, use :option:`numjobs` + = to get desired CPU usage, as the cpuload only loads a + single CPU at the desired rate. A job never finishes unless there is + at least one non-cpuio job. + + **guasi** + The GUASI I/O engine is the Generic Userspace Asyncronous Syscall + Interface approach to async I/O. See + + http://www.xmailserver.org/guasi-lib.html + + for more info on GUASI. + + **rdma** + The RDMA I/O engine supports both RDMA memory semantics + (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the + InfiniBand, RoCE and iWARP protocols. + + **falloc** + I/O engine that does regular fallocate to simulate data transfer as + fio ioengine. + + DDIR_READ + does fallocate(,mode = FALLOC_FL_KEEP_SIZE,). + + DDIR_WRITE + does fallocate(,mode = 0). + + DDIR_TRIM + does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE). + + **e4defrag** + I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate + defragment activity in request to DDIR_WRITE event. + + **rbd** + I/O engine supporting direct access to Ceph Rados Block Devices + (RBD) via librbd without the need to use the kernel rbd driver. This + ioengine defines engine specific options. + + **gfapi** + Using Glusterfs libgfapi sync interface to direct access to + Glusterfs volumes without having to go through FUSE. This ioengine + defines engine specific options. + + **gfapi_async** + Using Glusterfs libgfapi async interface to direct access to + Glusterfs volumes without having to go through FUSE. This ioengine + defines engine specific options. + + **libhdfs** + Read and write through Hadoop (HDFS). The :file:`filename` option + is used to specify host,port of the hdfs name-node to connect. This + engine interprets offsets a little differently. In HDFS, files once + created cannot be modified. So random writes are not possible. To + imitate this, libhdfs engine expects bunch of small files to be + created over HDFS, and engine will randomly pick a file out of those + files based on the offset generated by fio backend. (see the example + job file to create such files, use ``rw=write`` option). Please + note, you might want to set necessary environment variables to work + with hdfs/libhdfs properly. Each jobs uses it's own connection to + HDFS. + + **mtd** + Read, write and erase an MTD character device (e.g., + :file:`/dev/mtd0`). Discards are treated as erases. Depending on the + underlying device type, the I/O may have to go in a certain pattern, + e.g., on NAND, writing sequentially to erase blocks and discarding + before overwriting. The writetrim mode works well for this + constraint. + + **pmemblk** + Read and write using filesystem DAX to a file on a filesystem + mounted with DAX on a persistent memory device through the NVML + libpmemblk library. + + **dev-dax** + Read and write using device DAX to a persistent memory device (e.g., + /dev/dax0.0) through the NVML libpmem library. + + **external** + Prefix to specify loading an external I/O engine object file. Append + the engine filename, eg ``ioengine=external:/tmp/foo.o`` to load + ioengine :file:`foo.o` in :file:`/tmp`. + + +I/O engine specific parameters +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In addition, there are some parameters which are only valid when a specific +ioengine is in use. These are used identically to normal parameters, with the +caveat that when used on the command line, they must come after the +:option:`ioengine` that defines them is selected. + +.. option:: userspace_reap : [libaio] + + Normally, with the libaio engine in use, fio will use the + :manpage:`io_getevents(2)` system call to reap newly returned events. With + this flag turned on, the AIO ring will be read directly from user-space to + reap events. The reaping mode is only enabled when polling for a minimum of + 0 events (eg when :option:`iodepth_batch_complete` `=0`). + +.. option:: hipri : [psyncv2] + + Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority + than normal. + +.. option:: cpuload=int : [cpuio] + + Attempt to use the specified percentage of CPU cycles. + +.. option:: cpuchunks=int : [cpuio] + + Split the load into cycles of the given time. In microseconds. + +.. option:: exit_on_io_done=bool : [cpuio] + + Detect when I/O threads are done, then exit. + +.. option:: hostname=str : [netsplice] [net] + + The host name or IP address to use for TCP or UDP based I/O. If the job is + a TCP listener or UDP reader, the host name is not used and must be omitted + unless it is a valid UDP multicast address. + +.. option:: namenode=str : [libhdfs] + + The host name or IP address of a HDFS cluster namenode to contact. + +.. option:: port=int + + [netsplice], [net] + + The TCP or UDP port to bind to or connect to. If this is used with + :option:`numjobs` to spawn multiple instances of the same job type, then + this will be the starting port number since fio will use a range of + ports. + + [libhdfs] + + the listening port of the HFDS cluster namenode. + +.. option:: interface=str : [netsplice] [net] + + The IP address of the network interface used to send or receive UDP + multicast. + +.. option:: ttl=int : [netsplice] [net] + + Time-to-live value for outgoing UDP multicast packets. Default: 1. + +.. option:: nodelay=bool : [netsplice] [net] + + Set TCP_NODELAY on TCP connections. + +.. option:: protocol=str : [netsplice] [net] + +.. option:: proto=str : [netsplice] [net] + + The network protocol to use. Accepted values are: + + **tcp** + Transmission control protocol. + **tcpv6** + Transmission control protocol V6. + **udp** + User datagram protocol. + **udpv6** + User datagram protocol V6. + **unix** + UNIX domain socket. + + When the protocol is TCP or UDP, the port must also be given, as well as the + hostname if the job is a TCP listener or UDP reader. For unix sockets, the + normal filename option should be used and the port is invalid. + +.. option:: listen : [net] + + For TCP network connections, tell fio to listen for incoming connections + rather than initiating an outgoing connection. The :option:`hostname` must + be omitted if this option is used. + +.. option:: pingpong : [net] + + Normally a network writer will just continue writing data, and a network + reader will just consume packages. If ``pingpong=1`` is set, a writer will + send its normal payload to the reader, then wait for the reader to send the + same payload back. This allows fio to measure network latencies. The + submission and completion latencies then measure local time spent sending or + receiving, and the completion latency measures how long it took for the + other end to receive and send back. For UDP multicast traffic + ``pingpong=1`` should only be set for a single reader when multiple readers + are listening to the same address. + +.. option:: window_size : [net] + + Set the desired socket buffer size for the connection. + +.. option:: mss : [net] + + Set the TCP maximum segment size (TCP_MAXSEG). + +.. option:: donorname=str : [e4defrag] + + File will be used as a block donor(swap extents between files). + +.. option:: inplace=int : [e4defrag] + + Configure donor file blocks allocation strategy: + + **0** + Default. Preallocate donor's file on init. + **1** + Allocate space immediately inside defragment event, and free right + after event. + +.. option:: clustername=str : [rbd] + + Specifies the name of the Ceph cluster. + +.. option:: rbdname=str : [rbd] + + Specifies the name of the RBD. + +.. option:: pool=str : [rbd] + + Specifies the name of the Ceph pool containing RBD. + +.. option:: clientname=str : [rbd] + + Specifies the username (without the 'client.' prefix) used to access the + Ceph cluster. If the *clustername* is specified, the *clientname* shall be + the full *type.id* string. If no type. prefix is given, fio will add + 'client.' by default. + +.. option:: skip_bad=bool : [mtd] + + Skip operations against known bad blocks. + +.. option:: hdfsdirectory : [libhdfs] + + libhdfs will create chunk in this HDFS directory. + +.. option:: chunk_size : [libhdfs] + + the size of the chunk to use for each file. + + +I/O depth +~~~~~~~~~ + +.. option:: iodepth=int + + Number of I/O units to keep in flight against the file. Note that + increasing *iodepth* beyond 1 will not affect synchronous ioengines (except + for small degress when :option:`verify_async` is in use). Even async + engines may impose OS restrictions causing the desired depth not to be + achieved. This may happen on Linux when using libaio and not setting + :option:`direct` =1, since buffered I/O is not async on that OS. Keep an + eye on the I/O depth distribution in the fio output to verify that the + achieved depth is as expected. Default: 1. + +.. option:: iodepth_batch_submit=int, iodepth_batch=int + + This defines how many pieces of I/O to submit at once. It defaults to 1 + which means that we submit each I/O as soon as it is available, but can be + raised to submit bigger batches of I/O at the time. If it is set to 0 the + :option:`iodepth` value will be used. + +.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int + + This defines how many pieces of I/O to retrieve at once. It defaults to 1 + which means that we'll ask for a minimum of 1 I/O in the retrieval process + from the kernel. The I/O retrieval will go on until we hit the limit set by + :option:`iodepth_low`. If this variable is set to 0, then fio will always + check for completed events before queuing more I/O. This helps reduce I/O + latency, at the cost of more retrieval system calls. + +.. option:: iodepth_batch_complete_max=int + + This defines maximum pieces of I/O to retrieve at once. This variable should + be used along with :option:`iodepth_batch_complete_min` =int variable, + specifying the range of min and max amount of I/O which should be + retrieved. By default it is equal to :option:`iodepth_batch_complete_min` + value. + + Example #1:: + + iodepth_batch_complete_min=1 + iodepth_batch_complete_max= + + which means that we will retrieve at least 1 I/O and up to the whole + submitted queue depth. If none of I/O has been completed yet, we will wait. + + Example #2:: + + iodepth_batch_complete_min=0 + iodepth_batch_complete_max= + + which means that we can retrieve up to the whole submitted queue depth, but + if none of I/O has been completed yet, we will NOT wait and immediately exit + the system call. In this example we simply do polling. + +.. option:: iodepth_low=int + + The low water mark indicating when to start filling the queue + again. Defaults to the same as :option:`iodepth`, meaning that fio will + attempt to keep the queue full at all times. If :option:`iodepth` is set to + eg 16 and *iodepth_low* is set to 4, then after fio has filled the queue of + 16 requests, it will let the depth drain down to 4 before starting to fill + it again. + +.. option:: io_submit_mode=str + + This option controls how fio submits the I/O to the I/O engine. The default + is `inline`, which means that the fio job threads submit and reap I/O + directly. If set to `offload`, the job threads will offload I/O submission + to a dedicated pool of I/O threads. This requires some coordination and thus + has a bit of extra overhead, especially for lower queue depth I/O where it + can increase latencies. The benefit is that fio can manage submission rates + independently of the device completion rates. This avoids skewed latency + reporting if I/O gets back up on the device side (the coordinated omission + problem). + + +I/O rate +~~~~~~~~ + +.. option:: thinktime=int + + Stall the job x microseconds after an I/O has completed before issuing the + next. May be used to simulate processing being done by an application. See + :option:`thinktime_blocks` and :option:`thinktime_spin`. + +.. option:: thinktime_spin=int + + Only valid if :option:`thinktime` is set - pretend to spend CPU time doing + something with the data received, before falling back to sleeping for the + rest of the period specified by :option:`thinktime`. + +.. option:: thinktime_blocks=int + + Only valid if :option:`thinktime` is set - control how many blocks to issue, + before waiting `thinktime` usecs. If not set, defaults to 1 which will make + fio wait `thinktime` usecs after every block. This effectively makes any + queue depth setting redundant, since no more than 1 I/O will be queued + before we have to complete it and do our thinktime. In other words, this + setting effectively caps the queue depth if the latter is larger. + +.. option:: rate=int[,int][,int] + + Cap the bandwidth used by this job. The number is in bytes/sec, the normal + suffix rules apply. Comma-separated values may be specified for reads, + writes, and trims as described in :option:`blocksize`. + +.. option:: rate_min=int[,int][,int] + + Tell fio to do whatever it can to maintain at least this bandwidth. Failing + to meet this requirement will cause the job to exit. Comma-separated values + may be specified for reads, writes, and trims as described in + :option:`blocksize`. + +.. option:: rate_iops=int[,int][,int] + + Cap the bandwidth to this number of IOPS. Basically the same as + :option:`rate`, just specified independently of bandwidth. If the job is + given a block size range instead of a fixed value, the smallest block size + is used as the metric. Comma-separated values may be specified for reads, + writes, and trims as described in :option:`blocksize`. + +.. option:: rate_iops_min=int[,int][,int] + + If fio doesn't meet this rate of I/O, it will cause the job to exit. + Comma-separated values may be specified for reads, writes, and trims as + described in :option:`blocksize`. + +.. option:: rate_process=str + + This option controls how fio manages rated I/O submissions. The default is + `linear`, which submits I/O in a linear fashion with fixed delays between + IOs that gets adjusted based on I/O completion rates. If this is set to + `poisson`, fio will submit I/O based on a more real world random request + flow, known as the Poisson process + (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be + 10^6 / IOPS for the given workload. + + +I/O latency +~~~~~~~~~~~ + +.. option:: latency_target=int + + If set, fio will attempt to find the max performance point that the given + workload will run at while maintaining a latency below this target. The + values is given in microseconds. See :option:`latency_window` and + :option:`latency_percentile`. + +.. option:: latency_window=int + + Used with :option:`latency_target` to specify the sample window that the job + is run at varying queue depths to test the performance. The value is given + in microseconds. + +.. option:: latency_percentile=float + + The percentage of IOs that must fall within the criteria specified by + :option:`latency_target` and :option:`latency_window`. If not set, this + defaults to 100.0, meaning that all IOs must be equal or below to the value + set by :option:`latency_target`. + +.. option:: max_latency=int + + If set, fio will exit the job if it exceeds this maximum latency. It will + exit with an ETIME error. + +.. option:: rate_cycle=int + + Average bandwidth for :option:`rate` and :option:`rate_min` over this number + of milliseconds. + + +I/O replay +~~~~~~~~~~ + +.. option:: write_iolog=str + + Write the issued I/O patterns to the specified file. See + :option:`read_iolog`. Specify a separate file for each job, otherwise the + iologs will be interspersed and the file may be corrupt. + +.. option:: read_iolog=str + + Open an iolog with the specified file name and replay the I/O patterns it + contains. This can be used to store a workload and replay it sometime + later. The iolog given may also be a blktrace binary file, which allows fio + to replay a workload captured by :command:`blktrace`. See + :manpage:`blktrace(8)` for how to capture such logging data. For blktrace + replay, the file needs to be turned into a blkparse binary data file first + (``blkparse -o /dev/null -d file_for_fio.bin``). + +.. option:: replay_no_stall=int + + When replaying I/O with :option:`read_iolog` the default behavior is to + attempt to respect the time stamps within the log and replay them with the + appropriate delay between IOPS. By setting this variable fio will not + respect the timestamps and attempt to replay them as fast as possible while + still respecting ordering. The result is the same I/O pattern to a given + device, but different timings. + +.. option:: replay_redirect=str + + While replaying I/O patterns using :option:`read_iolog` the default behavior + is to replay the IOPS onto the major/minor device that each IOP was recorded + from. This is sometimes undesirable because on a different machine those + major/minor numbers can map to a different device. Changing hardware on the + same system can also result in a different major/minor mapping. + ``replay_redirect`` causes all IOPS to be replayed onto the single specified + device regardless of the device it was recorded + from. i.e. :option:`replay_redirect` = :file:`/dev/sdc` would cause all I/O + in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means + multiple devices will be replayed onto a single device, if the trace + contains multiple devices. If you want multiple devices to be replayed + concurrently to multiple redirected devices you must blkparse your trace + into separate traces and replay them with independent fio invocations. + Unfortunately this also breaks the strict time ordering between multiple + device accesses. + +.. option:: replay_align=int + + Force alignment of I/O offsets and lengths in a trace to this power of 2 + value. + +.. option:: replay_scale=int + + Scale sector offsets down by this factor when replaying traces. + + +Threads, processes and job synchronization +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. option:: thread + + Fio defaults to forking jobs, however if this option is given, fio will use + :manpage:`pthread_create(3)` to create threads instead. + +.. option:: wait_for=str + + Specifies the name of the already defined job to wait for. Single waitee + name only may be specified. If set, the job won't be started until all + workers of the waitee job are done. + + ``wait_for`` operates on the job name basis, so there are a few + limitations. First, the waitee must be defined prior to the waiter job + (meaning no forward references). Second, if a job is being referenced as a + waitee, it must have a unique name (no duplicate waitees). + +.. option:: nice=int + + Run the job with the given nice value. See man :manpage:`nice(2)`. + + On Windows, values less than -15 set the process class to "High"; -1 through + -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle" + priority class. + +.. option:: prio=int + + Set the I/O priority value of this job. Linux limits us to a positive value + between 0 and 7, with 0 being the highest. See man + :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating + systems since meaning of priority may differ. + +.. option:: prioclass=int + + Set the I/O priority class. See man :manpage:`ionice(1)`. + +.. option:: cpumask=int + + Set the CPU affinity of this job. The parameter given is a bitmask of + allowed CPU's the job may run on. So if you want the allowed CPUs to be 1 + and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man + :manpage:`sched_setaffinity(2)`. This may not work on all supported + operating systems or kernel versions. This option doesn't work well for a + higher CPU count than what you can store in an integer mask, so it can only + control cpus 1-32. For boxes with larger CPU counts, use + :option:`cpus_allowed`. + +.. option:: cpus_allowed=str + + Controls the same options as :option:`cpumask`, but it allows a text setting + of the permitted CPUs instead. So to use CPUs 1 and 5, you would specify + ``cpus_allowed=1,5``. This options also allows a range of CPUs. Say you + wanted a binding to CPUs 1, 5, and 8-15, you would set + ``cpus_allowed=1,5,8-15``. + +.. option:: cpus_allowed_policy=str + + Set the policy of how fio distributes the CPUs specified by + :option:`cpus_allowed` or cpumask. Two policies are supported: + + **shared** + All jobs will share the CPU set specified. + **split** + Each job will get a unique CPU from the CPU set. + + **shared** is the default behaviour, if the option isn't specified. If + **split** is specified, then fio will will assign one cpu per job. If not + enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs + in the set. + +.. option:: numa_cpu_nodes=str + + Set this job running on specified NUMA nodes' CPUs. The arguments allow + comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable + numa options support, fio must be built on a system with libnuma-dev(el) + installed. + +.. option:: numa_mem_policy=str + + Set this job's memory policy and corresponding NUMA nodes. Format of the + arguments:: + + [:] + + ``mode`` is one of the following memory policy: ``default``, ``prefer``, + ``bind``, ``interleave``, ``local`` For ``default`` and ``local`` memory + policy, no node is needed to be specified. For ``prefer``, only one node is + allowed. For ``bind`` and ``interleave``, it allow comma delimited list of + numbers, A-B ranges, or `all`. + +.. option:: cgroup=str + + Add job to this control group. If it doesn't exist, it will be created. The + system must have a mounted cgroup blkio mount point for this to work. If + your system doesn't have it mounted, you can do so with:: + + # mount -t cgroup -o blkio none /cgroup + +.. option:: cgroup_weight=int + + Set the weight of the cgroup to this value. See the documentation that comes + with the kernel, allowed values are in the range of 100..1000. + +.. option:: cgroup_nodelete=bool + + Normally fio will delete the cgroups it has created after the job + completion. To override this behavior and to leave cgroups around after the + job completion, set ``cgroup_nodelete=1``. This can be useful if one wants + to inspect various cgroup files after job completion. Default: false. + +.. option:: flow_id=int + + The ID of the flow. If not specified, it defaults to being a global + flow. See :option:`flow`. + +.. option:: flow=int + + Weight in token-based flow control. If this value is used, then there is a + 'flow counter' which is used to regulate the proportion of activity between + two or more jobs. Fio attempts to keep this flow counter near zero. The + ``flow`` parameter stands for how much should be added or subtracted to the + flow counter on each iteration of the main I/O loop. That is, if one job has + ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8 + ratio in how much one runs vs the other. + +.. option:: flow_watermark=int + + The maximum value that the absolute value of the flow counter is allowed to + reach before the job must wait for a lower value of the counter. + +.. option:: flow_sleep=int + + The period of time, in microseconds, to wait after the flow watermark has + been exceeded before retrying operations. + +.. option:: stonewall, wait_for_previous + + Wait for preceding jobs in the job file to exit, before starting this + one. Can be used to insert serialization points in the job file. A stone + wall also implies starting a new reporting group, see + :option:`group_reporting`. + +.. option:: exitall + + When one job finishes, terminate the rest. The default is to wait for each + job to finish, sometimes that is not the desired action. + +.. option:: exec_prerun=str + + Before running this job, issue the command specified through + :manpage:`system(3)`. Output is redirected in a file called + :file:`jobname.prerun.txt`. + +.. option:: exec_postrun=str + + After the job completes, issue the command specified though + :manpage:`system(3)`. Output is redirected in a file called + :file:`jobname.postrun.txt`. + +.. option:: uid=int + + Instead of running as the invoking user, set the user ID to this value + before the thread/process does any work. + +.. option:: gid=int + + Set group ID, see :option:`uid`. + + +Verification +~~~~~~~~~~~~ + +.. option:: verify_only + + Do not perform specified workload, only verify data still matches previous + invocation of this workload. This option allows one to check data multiple + times at a later date without overwriting it. This option makes sense only + for workloads that write data, and does not support workloads with the + :option:`time_based` option set. + +.. option:: do_verify=bool + + Run the verify phase after a write phase. Only valid if :option:`verify` is + set. Default: true. + +.. option:: verify=str + + If writing to a file, fio can verify the file contents after each iteration + of the job. Each verification method also implies verification of special + header, which is written to the beginning of each block. This header also + includes meta information, like offset of the block, block number, timestamp + when block was written, etc. :option:`verify` can be combined with + :option:`verify_pattern` option. The allowed values are: + + **md5** + Use an md5 sum of the data area and store it in the header of + each block. + + **crc64** + Use an experimental crc64 sum of the data area and store it in the + header of each block. + + **crc32c** + Use a crc32c sum of the data area and store it in the header of each + block. + + **crc32c-intel** + Use hardware assisted crc32c calculation provided on SSE4.2 enabled + processors. Falls back to regular software crc32c, if not supported + by the system. + + **crc32** + Use a crc32 sum of the data area and store it in the header of each + block. + + **crc16** + Use a crc16 sum of the data area and store it in the header of each + block. + + **crc7** + Use a crc7 sum of the data area and store it in the header of each + block. + + **xxhash** + Use xxhash as the checksum function. Generally the fastest software + checksum that fio supports. + + **sha512** + Use sha512 as the checksum function. + + **sha256** + Use sha256 as the checksum function. + + **sha1** + Use optimized sha1 as the checksum function. + + **meta** + This option is deprecated, since now meta information is included in + generic verification header and meta verification happens by + default. For detailed information see the description of the + :option:`verify` setting. This option is kept because of + compatibility's sake with old configurations. Do not use it. + + **pattern** + Verify a strict pattern. Normally fio includes a header with some + basic information and checksumming, but if this option is set, only + the specific pattern set with :option:`verify_pattern` is verified. + + **null** + Only pretend to verify. Useful for testing internals with + :option:`ioengine` `=null`, not for much else. + + This option can be used for repeated burn-in tests of a system to make sure + that the written data is also correctly read back. If the data direction + given is a read or random read, fio will assume that it should verify a + previously written file. If the data direction includes any form of write, + the verify will be of the newly written data. + +.. option:: verifysort=bool + + If true, fio will sort written verify blocks when it deems it faster to read + them back in a sorted manner. This is often the case when overwriting an + existing file, since the blocks are already laid out in the file system. You + can ignore this option unless doing huge amounts of really fast I/O where + the red-black tree sorting CPU time becomes significant. Default: true. + +.. option:: verifysort_nr=int + + Pre-load and sort verify blocks for a read workload. + +.. option:: verify_offset=int + + Swap the verification header with data somewhere else in the block before + writing. It is swapped back before verifying. + +.. option:: verify_interval=int + + Write the verification header at a finer granularity than the + :option:`blocksize`. It will be written for chunks the size of + ``verify_interval``. :option:`blocksize` should divide this evenly. + +.. option:: verify_pattern=str + + If set, fio will fill the I/O buffers with this pattern. Fio defaults to + filling with totally random bytes, but sometimes it's interesting to fill + with a known pattern for I/O verification purposes. Depending on the width + of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time(it can + be either a decimal or a hex number). The ``verify_pattern`` if larger than + a 32-bit quantity has to be a hex number that starts with either "0x" or + "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o + format, which means that for each block offset will be written and then + verified back, e.g.:: + + verify_pattern=%o + + Or use combination of everything:: + + verify_pattern=0xff%o"abcd"-12 + +.. option:: verify_fatal=bool + + Normally fio will keep checking the entire contents before quitting on a + block verification failure. If this option is set, fio will exit the job on + the first observed failure. Default: false. + +.. option:: verify_dump=bool + + If set, dump the contents of both the original data block and the data block + we read off disk to files. This allows later analysis to inspect just what + kind of data corruption occurred. Off by default. + +.. option:: verify_async=int + + Fio will normally verify I/O inline from the submitting thread. This option + takes an integer describing how many async offload threads to create for I/O + verification instead, causing fio to offload the duty of verifying I/O + contents to one or more separate threads. If using this offload option, even + sync I/O engines can benefit from using an :option:`iodepth` setting higher + than 1, as it allows them to have I/O in flight while verifies are running. + +.. option:: verify_async_cpus=str + + Tell fio to set the given CPU affinity on the async I/O verification + threads. See :option:`cpus_allowed` for the format used. + +.. option:: verify_backlog=int + + Fio will normally verify the written contents of a job that utilizes verify + once that job has completed. In other words, everything is written then + everything is read back and verified. You may want to verify continually + instead for a variety of reasons. Fio stores the meta data associated with + an I/O block in memory, so for large verify workloads, quite a bit of memory + would be used up holding this meta data. If this option is enabled, fio will + write only N blocks before verifying these blocks. + +.. option:: verify_backlog_batch=int + + Control how many blocks fio will verify if :option:`verify_backlog` is + set. If not set, will default to the value of :option:`verify_backlog` + (meaning the entire queue is read back and verified). If + ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all + blocks will be verified, if ``verify_backlog_batch`` is larger than + :option:`verify_backlog`, some blocks will be verified more than once. + +.. option:: verify_state_save=bool + + When a job exits during the write phase of a verify workload, save its + current state. This allows fio to replay up until that point, if the verify + state is loaded for the verify read phase. The format of the filename is, + roughly:: + + ---verify.state. + + is "local" for a local run, "sock" for a client/server socket + connection, and "ip" (192.168.0.1, for instance) for a networked + client/server connection. + +.. option:: verify_state_load=bool + + If a verify termination trigger was used, fio stores the current write state + of each thread. This can be used at verification time so that fio knows how + far it should verify. Without this information, fio will run a full + verification pass, according to the settings in the job file used. + +.. option:: trim_percentage=int + + Number of verify blocks to discard/trim. + +.. option:: trim_verify_zero=bool + + Verify that trim/discarded blocks are returned as zeroes. + +.. option:: trim_backlog=int + + Verify that trim/discarded blocks are returned as zeroes. + +.. option:: trim_backlog_batch=int + + Trim this number of I/O blocks. + +.. option:: experimental_verify=bool + + Enable experimental verification. + + +Steady state +~~~~~~~~~~~~ + +.. option:: steadystate=str:float, ss=str:float + + Define the criterion and limit for assessing steady state performance. The + first parameter designates the criterion whereas the second parameter sets + the threshold. When the criterion falls below the threshold for the + specified duration, the job will stop. For example, `iops_slope:0.1%` will + direct fio to terminate the job when the least squares regression slope + falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled + this will apply to all jobs in the group. Below is the list of available + steady state assessment criteria. All assessments are carried out using only + data from the rolling collection window. Threshold limits can be expressed + as a fixed value or as a percentage of the mean in the collection window. + + **iops** + Collect IOPS data. Stop the job if all individual IOPS measurements + are within the specified limit of the mean IOPS (e.g., ``iops:2`` + means that all individual IOPS values must be within 2 of the mean, + whereas ``iops:0.2%`` means that all individual IOPS values must be + within 0.2% of the mean IOPS to terminate the job). + + **iops_slope** + Collect IOPS data and calculate the least squares regression + slope. Stop the job if the slope falls below the specified limit. + + **bw** + Collect bandwidth data. Stop the job if all individual bandwidth + measurements are within the specified limit of the mean bandwidth. + + **bw_slope** + Collect bandwidth data and calculate the least squares regression + slope. Stop the job if the slope falls below the specified limit. + +.. option:: steadystate_duration=time, ss_dur=time + + A rolling window of this duration will be used to judge whether steady state + has been reached. Data will be collected once per second. The default is 0 + which disables steady state detection. + +.. option:: steadystate_ramp_time=time, ss_ramp=time + + Allow the job to run for the specified duration before beginning data + collection for checking the steady state job termination criterion. The + default is 0. + + +Measurements and reporting +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. option:: per_job_logs=bool + + If set, this generates bw/clat/iops log with per file private filenames. If + not set, jobs with identical names will share the log filename. Default: + true. + +.. option:: group_reporting + + It may sometimes be interesting to display statistics for groups of jobs as + a whole instead of for each individual job. This is especially true if + :option:`numjobs` is used; looking at individual thread/process output + quickly becomes unwieldy. To see the final report per-group instead of + per-job, use :option:`group_reporting`. Jobs in a file will be part of the + same reporting group, unless if separated by a :option:`stonewall`, or by + using :option:`new_group`. + +.. option:: new_group + + Start a new reporting group. See: :option:`group_reporting`. If not given, + all jobs in a file will be part of the same reporting group, unless + separated by a :option:`stonewall`. + +.. option:: write_bw_log=str + + If given, write a bandwidth log for this job. Can be used to store data of + the bandwidth of the jobs in their lifetime. The included + :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these + text files into nice graphs. See :option:`write_lat_log` for behaviour of + given filename. For this option, the postfix is :file:`_bw.x.log`, where `x` + is the index of the job (`1..N`, where `N` is the number of jobs). If + :option:`per_job_logs` is false, then the filename will not include the job + index. See `Log File Formats`_. + +.. option:: write_lat_log=str + + Same as :option:`write_bw_log`, except that this option stores I/O + submission, completion, and total latencies instead. If no filename is given + with this option, the default filename of :file:`jobname_type.log` is + used. Even if the filename is given, fio will still append the type of + log. So if one specifies:: + + write_lat_log=foo + + The actual log names will be :file:`foo_slat.x.log`, :file:`foo_clat.x.log`, + and :file:`foo_lat.x.log`, where `x` is the index of the job (1..N, where N + is the number of jobs). This helps :command:`fio_generate_plot` find the + logs automatically. If :option:`per_job_logs` is false, then the filename + will not include the job index. See `Log File Formats`_. + +.. option:: write_hist_log=str + + Same as :option:`write_lat_log`, but writes I/O completion latency + histograms. If no filename is given with this option, the default filename + of :file:`jobname_clat_hist.x.log` is used, where `x` is the index of the + job (1..N, where `N` is the number of jobs). Even if the filename is given, + fio will still append the type of log. If :option:`per_job_logs` is false, + then the filename will not include the job index. See `Log File Formats`_. + +.. option:: write_iops_log=str + + Same as :option:`write_bw_log`, but writes IOPS. If no filename is given + with this option, the default filename of :file:`jobname_type.x.log` is + used,where `x` is the index of the job (1..N, where `N` is the number of + jobs). Even if the filename is given, fio will still append the type of + log. If :option:`per_job_logs` is false, then the filename will not include + the job index. See `Log File Formats`_. + +.. option:: log_avg_msec=int + + By default, fio will log an entry in the iops, latency, or bw log for every + I/O that completes. When writing to the disk log, that can quickly grow to a + very large size. Setting this option makes fio average the each log entry + over the specified period of time, reducing the resolution of the log. See + :option:`log_max_value` as well. Defaults to 0, logging all entries. + +.. option:: log_hist_msec=int + + Same as :option:`log_avg_msec`, but logs entries for completion latency + histograms. Computing latency percentiles from averages of intervals using + :option:`log_avg_msec` is innacurate. Setting this option makes fio log + histogram entries over the specified period of time, reducing log sizes for + high IOPS devices while retaining percentile accuracy. See + :option:`log_hist_coarseness` as well. Defaults to 0, meaning histogram + logging is disabled. + +.. option:: log_hist_coarseness=int + + Integer ranging from 0 to 6, defining the coarseness of the resolution of + the histogram logs enabled with :option:`log_hist_msec`. For each increment + in coarseness, fio outputs half as many bins. Defaults to 0, for which + histogram logs contain 1216 latency bins. See `Log File Formats`_. + +.. option:: log_max_value=bool + + If :option:`log_avg_msec` is set, fio logs the average over that window. If + you instead want to log the maximum value, set this option to 1. Defaults to + 0, meaning that averaged values are logged. + +.. option:: log_offset=int + + If this is set, the iolog options will include the byte offset for the I/O + entry as well as the other data values. + +.. option:: log_compression=int + + If this is set, fio will compress the I/O logs as it goes, to keep the + memory footprint lower. When a log reaches the specified size, that chunk is + removed and compressed in the background. Given that I/O logs are fairly + highly compressible, this yields a nice memory savings for longer runs. The + downside is that the compression will consume some background CPU cycles, so + it may impact the run. This, however, is also true if the logging ends up + consuming most of the system memory. So pick your poison. The I/O logs are + saved normally at the end of a run, by decompressing the chunks and storing + them in the specified log file. This feature depends on the availability of + zlib. + +.. option:: log_compression_cpus=str + + Define the set of CPUs that are allowed to handle online log compression for + the I/O jobs. This can provide better isolation between performance + sensitive jobs, and background compression work. + +.. option:: log_store_compressed=bool + + If set, fio will store the log files in a compressed format. They can be + decompressed with fio, using the :option:`--inflate-log` command line + parameter. The files will be stored with a :file:`.fz` suffix. + +.. option:: log_unix_epoch=bool + + If set, fio will log Unix timestamps to the log files produced by enabling + write_type_log for each log type, instead of the default zero-based + timestamps. + +.. option:: block_error_percentiles=bool + + If set, record errors in trim block-sized units from writes and trims and + output a histogram of how many trims it took to get to errors, and what kind + of error was encountered. + +.. option:: bwavgtime=int + + Average the calculated bandwidth over the given time. Value is specified in + milliseconds. If the job also does bandwidth logging through + :option:`write_bw_log`, then the minimum of this option and + :option:`log_avg_msec` will be used. Default: 500ms. + +.. option:: iopsavgtime=int + + Average the calculated IOPS over the given time. Value is specified in + milliseconds. If the job also does IOPS logging through + :option:`write_iops_log`, then the minimum of this option and + :option:`log_avg_msec` will be used. Default: 500ms. + +.. option:: disk_util=bool + + Generate disk utilization statistics, if the platform supports it. + Default: true. + +.. option:: disable_lat=bool + + Disable measurements of total latency numbers. Useful only for cutting back + the number of calls to :manpage:`gettimeofday(2)`, as that does impact + performance at really high IOPS rates. Note that to really get rid of a + large amount of these calls, this option must be used with + :option:`disable_slat` and :option:`disable_bw` as well. + +.. option:: disable_clat=bool + + Disable measurements of completion latency numbers. See + :option:`disable_lat`. + +.. option:: disable_slat=bool + + Disable measurements of submission latency numbers. See + :option:`disable_slat`. + +.. option:: disable_bw=bool + + Disable measurements of throughput/bandwidth numbers. See + :option:`disable_lat`. + +.. option:: clat_percentiles=bool + + Enable the reporting of percentiles of completion latencies. + +.. option:: percentile_list=float_list + + Overwrite the default list of percentiles for completion latencies and the + block error histogram. Each number is a floating number in the range + (0,100], and the maximum length of the list is 20. Use ``:`` to separate the + numbers, and list the numbers in ascending order. For example, + ``--percentile_list=99.5:99.9`` will cause fio to report the values of + completion latency below which 99.5% and 99.9% of the observed latencies + fell, respectively. + + +Error handling +~~~~~~~~~~~~~~ + +.. option:: exitall_on_error + + When one job finishes in error, terminate the rest. The default is to wait + for each job to finish. + +.. option:: continue_on_error=str + + Normally fio will exit the job on the first observed failure. If this option + is set, fio will continue the job when there is a 'non-fatal error' (EIO or + EILSEQ) until the runtime is exceeded or the I/O size specified is + completed. If this option is used, there are two more stats that are + appended, the total error count and the first error. The error field given + in the stats is the first error that was hit during the run. + + The allowed values are: + + **none** + Exit on any I/O or verify errors. + + **read** + Continue on read errors, exit on all others. + + **write** + Continue on write errors, exit on all others. + + **io** + Continue on any I/O error, exit on all others. + + **verify** + Continue on verify errors, exit on all others. + + **all** + Continue on all errors. + + **0** + Backward-compatible alias for 'none'. + + **1** + Backward-compatible alias for 'all'. + +.. option:: ignore_error=str + + Sometimes you want to ignore some errors during test in that case you can + specify error list for each error type. + ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for + given error type is separated with ':'. Error may be symbol ('ENOSPC', + 'ENOMEM') or integer. Example:: + + ignore_error=EAGAIN,ENOSPC:122 + + This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from + WRITE. + +.. option:: error_dump=bool + + If set dump every error even if it is non fatal, true by default. If + disabled only fatal error will be dumped. + + +Interpreting the output +----------------------- + +Fio spits out a lot of output. While running, fio will display the status of the +jobs created. An example of that would be:: + + Jobs: 1: [_r] [24.8% done] [r=20992KiB/s,w=24064KiB/s,t=0KiB/s] [r=82,w=94,t=0 iops] [eta 00h:01m:31s] + +The characters inside the square brackets denote the current status of each +thread. The possible values (in typical life cycle order) are: + ++------+-----+-----------------------------------------------------------+ +| Idle | Run | | ++======+=====+===========================================================+ +| P | | Thread setup, but not started. | ++------+-----+-----------------------------------------------------------+ +| C | | Thread created. | ++------+-----+-----------------------------------------------------------+ +| I | | Thread initialized, waiting or generating necessary data. | ++------+-----+-----------------------------------------------------------+ +| | p | Thread running pre-reading file(s). | ++------+-----+-----------------------------------------------------------+ +| | R | Running, doing sequential reads. | ++------+-----+-----------------------------------------------------------+ +| | r | Running, doing random reads. | ++------+-----+-----------------------------------------------------------+ +| | W | Running, doing sequential writes. | ++------+-----+-----------------------------------------------------------+ +| | w | Running, doing random writes. | ++------+-----+-----------------------------------------------------------+ +| | M | Running, doing mixed sequential reads/writes. | ++------+-----+-----------------------------------------------------------+ +| | m | Running, doing mixed random reads/writes. | ++------+-----+-----------------------------------------------------------+ +| | F | Running, currently waiting for :manpage:`fsync(2)` | ++------+-----+-----------------------------------------------------------+ +| | V | Running, doing verification of written data. | ++------+-----+-----------------------------------------------------------+ +| E | | Thread exited, not reaped by main thread yet. | ++------+-----+-----------------------------------------------------------+ +| _ | | Thread reaped, or | ++------+-----+-----------------------------------------------------------+ +| X | | Thread reaped, exited with an error. | ++------+-----+-----------------------------------------------------------+ +| K | | Thread reaped, exited due to signal. | ++------+-----+-----------------------------------------------------------+ + +Fio will condense the thread string as not to take up more space on the command +line as is needed. For instance, if you have 10 readers and 10 writers running, +the output would look like this:: + + Jobs: 20 (f=20): [R(10),W(10)] [4.0% done] [r=20992KiB/s,w=24064KiB/s,t=0KiB/s] [r=82,w=94,t=0 iops] [eta 57m:36s] + +Fio will still maintain the ordering, though. So the above means that jobs 1..10 +are readers, and 11..20 are writers. + +The other values are fairly self explanatory -- number of threads currently +running and doing I/O, rate of I/O since last check (read speed listed first, +then write speed), and the estimated completion percentage and time for the +running group. It's impossible to estimate runtime of the following groups (if +any). Note that the string is displayed in order, so it's possible to tell which +of the jobs are currently doing what. The first character is the first job +defined in the job file, and so forth. + +When fio is done (or interrupted by :kbd:`ctrl-c`), it will show the data for +each thread, group of threads, and disks in that order. For each data direction, +the output looks like:: + + Client1 (g=0): err= 0: + write: io= 32MiB, bw= 666KiB/s, iops=89 , runt= 50320msec + slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92 + clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82 + bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68 + cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17 + IO depths : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0% + submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% + complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% + issued r/w: total=0/32768, short=0/0 + lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%, + lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0% + +The client number is printed, along with the group id and error of that +thread. Below is the I/O statistics, here for writes. In the order listed, they +denote: + +**io** + Number of megabytes I/O performed. + +**bw** + Average bandwidth rate. + +**iops** + Average IOs performed per second. + +**runt** + The runtime of that thread. + +**slat** + Submission latency (avg being the average, stdev being the standard + deviation). This is the time it took to submit the I/O. For sync I/O, + the slat is really the completion latency, since queue/complete is one + operation there. This value can be in milliseconds or microseconds, fio + will choose the most appropriate base and print that. In the example + above, milliseconds is the best scale. Note: in :option:`--minimal` mode + latencies are always expressed in microseconds. + +**clat** + Completion latency. Same names as slat, this denotes the time from + submission to completion of the I/O pieces. For sync I/O, clat will + usually be equal (or very close) to 0, as the time from submit to + complete is basically just CPU time (I/O has already been done, see slat + explanation). + +**bw** + Bandwidth. Same names as the xlat stats, but also includes an + approximate percentage of total aggregate bandwidth this thread received + in this group. This last value is only really useful if the threads in + this group are on the same disk, since they are then competing for disk + access. + +**cpu** + CPU usage. User and system time, along with the number of context + switches this thread went through, usage of system and user time, and + finally the number of major and minor page faults. The CPU utilization + numbers are averages for the jobs in that reporting group, while the + context and fault counters are summed. + +**IO depths** + The distribution of I/O depths over the job life time. The numbers are + divided into powers of 2, so for example the 16= entries includes depths + up to that value but higher than the previous entry. In other words, it + covers the range from 16 to 31. + +**IO submit** + How many pieces of I/O were submitting in a single submit call. Each + entry denotes that amount and below, until the previous entry -- eg, + 8=100% mean that we submitted anywhere in between 5-8 IOs per submit + call. + +**IO complete** + Like the above submit number, but for completions instead. + +**IO issued** + The number of read/write requests issued, and how many of them were + short. + +**IO latencies** + The distribution of I/O completion latencies. This is the time from when + I/O leaves fio and when it gets completed. The numbers follow the same + pattern as the I/O depths, meaning that 2=1.6% means that 1.6% of the + I/O completed within 2 msecs, 20=12.8% means that 12.8% of the I/O took + more than 10 msecs, but less than (or equal to) 20 msecs. + +After each client has been listed, the group statistics are printed. They +will look like this:: + + Run status group 0 (all jobs): + READ: io=64MB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec + WRITE: io=64MB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec + +For each data direction, it prints: + +**io** + Number of megabytes I/O performed. +**aggrb** + Aggregate bandwidth of threads in this group. +**minb** + The minimum average bandwidth a thread saw. +**maxb** + The maximum average bandwidth a thread saw. +**mint** + The smallest runtime of the threads in that group. +**maxt** + The longest runtime of the threads in that group. + +And finally, the disk statistics are printed. They will look like this:: + + Disk stats (read/write): + sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% + +Each value is printed for both reads and writes, with reads first. The +numbers denote: + +**ios** + Number of ios performed by all groups. +**merge** + Number of merges I/O the I/O scheduler. +**ticks** + Number of ticks we kept the disk busy. +**io_queue** + Total time spent in the disk queue. +**util** + The disk utilization. A value of 100% means we kept the disk + busy constantly, 50% would be a disk idling half of the time. + +It is also possible to get fio to dump the current output while it is running, +without terminating the job. To do that, send fio the **USR1** signal. You can +also get regularly timed dumps by using the :option:`--status-interval` +parameter, or by creating a file in :file:`/tmp` named +:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the +current output status. + + +Terse output +------------ + +For scripted usage where you typically want to generate tables or graphs of the +results, fio can output the results in a semicolon separated format. The format +is one long line of values, such as:: + + 2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00% + A description of this job goes here. + +The job description (if provided) follows on a second line. + +To enable terse output, use the :option:`--minimal` command line option. The +first value is the version of the terse output format. If the output has to be +changed for some reason, this number will be incremented by 1 to signify that +change. + +Split up, the format is as follows: + + :: + + terse version, fio version, jobname, groupid, error + + READ status:: + + Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec) + Submission latency: min, max, mean, stdev (usec) + Completion latency: min, max, mean, stdev (usec) + Completion latency percentiles: 20 fields (see below) + Total latency: min, max, mean, stdev (usec) + Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev + + WRITE status: + + :: + + Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec) + Submission latency: min, max, mean, stdev (usec) + Completion latency: min, max, mean, stdev(usec) + Completion latency percentiles: 20 fields (see below) + Total latency: min, max, mean, stdev (usec) + Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev + + CPU usage:: + + user, system, context switches, major faults, minor faults + + I/O depths:: + + <=1, 2, 4, 8, 16, 32, >=64 + + I/O latencies microseconds:: + + <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000 + + I/O latencies milliseconds:: + + <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000 + + Disk utilization:: + + Disk name, Read ios, write ios, + Read merges, write merges, + Read ticks, write ticks, + Time spent in queue, disk utilization percentage + + Additional Info (dependent on continue_on_error, default off):: + + total # errors, first error code + + Additional Info (dependent on description being set):: + + Text description + +Completion latency percentiles can be a grouping of up to 20 sets, so for the +terse output fio writes all of them. Each field will look like this:: + + 1.00%=6112 + +which is the Xth percentile, and the `usec` latency associated with it. + +For disk utilization, all disks used by fio are shown. So for each disk there +will be a disk utilization section. + + +Trace file format +----------------- + +There are two trace file format that you can encounter. The older (v1) format is +unsupported since version 1.20-rc3 (March 2008). It will still be described +below in case that you get an old trace and want to understand it. + +In any case the trace is a simple text file with a single action per line. + + +Trace file format v1 +~~~~~~~~~~~~~~~~~~~~ + +Each line represents a single I/O action in the following format:: + + rw, offset, length + +where `rw=0/1` for read/write, and the offset and length entries being in bytes. + +This format is not supported in fio versions => 1.20-rc3. + + +Trace file format v2 +~~~~~~~~~~~~~~~~~~~~ + +The second version of the trace file format was added in fio version 1.17. It +allows to access more then one file per trace and has a bigger set of possible +file actions. + +The first line of the trace file has to be:: + + fio version 2 iolog + +Following this can be lines in two different formats, which are described below. + +The file management format:: + + filename action + +The filename is given as an absolute path. The action can be one of these: + +**add** + Add the given filename to the trace. +**open** + Open the file with the given filename. The filename has to have + been added with the **add** action before. +**close** + Close the file with the given filename. The file has to have been + opened before. + + +The file I/O action format:: + + filename action offset length + +The `filename` is given as an absolute path, and has to have been added and +opened before it can be used with this format. The `offset` and `length` are +given in bytes. The `action` can be one of these: + +**wait** + Wait for `offset` microseconds. Everything below 100 is discarded. + The time is relative to the previous `wait` statement. +**read** + Read `length` bytes beginning from `offset`. +**write** + Write `length` bytes beginning from `offset`. +**sync** + :manpage:`fsync(2)` the file. +**datasync** + :manpage:`fdatasync(2)` the file. +**trim** + Trim the given file from the given `offset` for `length` bytes. + +CPU idleness profiling +---------------------- + +In some cases, we want to understand CPU overhead in a test. For example, we +test patches for the specific goodness of whether they reduce CPU usage. +Fio implements a balloon approach to create a thread per CPU that runs at idle +priority, meaning that it only runs when nobody else needs the cpu. +By measuring the amount of work completed by the thread, idleness of each CPU +can be derived accordingly. + +An unit work is defined as touching a full page of unsigned characters. Mean and +standard deviation of time to complete an unit work is reported in "unit work" +section. Options can be chosen to report detailed percpu idleness or overall +system idleness by aggregating percpu stats. + + +Verification and triggers +------------------------- + +Fio is usually run in one of two ways, when data verification is done. The first +is a normal write job of some sort with verify enabled. When the write phase has +completed, fio switches to reads and verifies everything it wrote. The second +model is running just the write phase, and then later on running the same job +(but with reads instead of writes) to repeat the same I/O patterns and verify +the contents. Both of these methods depend on the write phase being completed, +as fio otherwise has no idea how much data was written. + +With verification triggers, fio supports dumping the current write state to +local files. Then a subsequent read verify workload can load this state and know +exactly where to stop. This is useful for testing cases where power is cut to a +server in a managed fashion, for instance. + +A verification trigger consists of two things: + +1) Storing the write state of each job. +2) Executing a trigger command. + +The write state is relatively small, on the order of hundreds of bytes to single +kilobytes. It contains information on the number of completions done, the last X +completions, etc. + +A trigger is invoked either through creation ('touch') of a specified file in +the system, or through a timeout setting. If fio is run with +:option:`--trigger-file` = :file:`/tmp/trigger-file`, then it will continually +check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it +will fire off the trigger (thus saving state, and executing the trigger +command). + +For client/server runs, there's both a local and remote trigger. If fio is +running as a server backend, it will send the job states back to the client for +safe storage, then execute the remote trigger, if specified. If a local trigger +is specified, the server will still send back the write state, but the client +will then execute the trigger. + +Verification trigger example +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Lets say we want to run a powercut test on the remote machine 'server'. Our +write workload is in :file:`write-test.fio`. We want to cut power to 'server' at +some point during the run, and we'll run this test from the safety or our local +machine, 'localbox'. On the server, we'll start the fio backend normally:: + + server# fio --server + +and on the client, we'll fire off the workload:: + + localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\"" + +We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute:: + + echo b > /proc/sysrq-trigger + +on the server once it has received the trigger and sent us the write state. This +will work, but it's not **really** cutting power to the server, it's merely +abruptly rebooting it. If we have a remote way of cutting power to the server +through IPMI or similar, we could do that through a local trigger command +instead. Lets assume we have a script that does IPMI reboot of a given hostname, +ipmi-reboot. On localbox, we could then have run fio with a local trigger +instead:: + + localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server" + +For this case, fio would wait for the server to send us the write state, then +execute ``ipmi-reboot server`` when that happened. + +Loading verify state +~~~~~~~~~~~~~~~~~~~~ + +To load store write state, read verification job file must contain the +:option:`verify_state_load` option. If that is set, fio will load the previously +stored state. For a local fio run this is done by loading the files directly, +and on a client/server run, the server backend will ask the client to send the +files over and load them from there. + + +Log File Formats +---------------- + +Fio supports a variety of log file formats, for logging latencies, bandwidth, +and IOPS. The logs share a common format, which looks like this: + + *time* (`msec`), *value*, *data direction*, *offset* + +Time for the log entry is always in milliseconds. The *value* logged depends +on the type of log, it will be one of the following: + + **Latency log** + Value is latency in usecs + **Bandwidth log** + Value is in KiB/sec + **IOPS log** + Value is IOPS + +*Data direction* is one of the following: + + **0** + I/O is a READ + **1** + I/O is a WRITE + **2** + I/O is a TRIM + +The *offset* is the offset, in bytes, from the start of the file, for that +particular I/O. The logging of the offset can be toggled with +:option:`log_offset`. + +If windowed logging is enabled through :option:`log_avg_msec` then fio doesn't +log individual IOs. Instead of logs the average values over the specified period +of time. Since 'data direction' and 'offset' are per-I/O values, they aren't +applicable if windowed logging is enabled. If windowed logging is enabled and +:option:`log_max_value` is set, then fio logs maximum values in that window +instead of averages. + + +Client/server +------------- + +Normally fio is invoked as a stand-alone application on the machine where the +I/O workload should be generated. However, the frontend and backend of fio can +be run separately. Ie the fio server can generate an I/O workload on the "Device +Under Test" while being controlled from another machine. + +Start the server on the machine which has access to the storage DUT:: + + fio --server=args + +where args defines what fio listens to. The arguments are of the form +``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP +v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket. +*hostname* is either a hostname or IP address, and *port* is the port to listen +to (only valid for TCP/IP, not a local socket). Some examples: + +1) ``fio --server`` + + Start a fio server, listening on all interfaces on the default port (8765). + +2) ``fio --server=ip:hostname,4444`` + + Start a fio server, listening on IP belonging to hostname and on port 4444. + +3) ``fio --server=ip6:::1,4444`` + + Start a fio server, listening on IPv6 localhost ::1 and on port 4444. + +4) ``fio --server=,4444`` + + Start a fio server, listening on all interfaces on port 4444. + +5) ``fio --server=1.2.3.4`` + + Start a fio server, listening on IP 1.2.3.4 on the default port. + +6) ``fio --server=sock:/tmp/fio.sock`` + + Start a fio server, listening on the local socket /tmp/fio.sock. + +Once a server is running, a "client" can connect to the fio server with:: + + fio --client= + +where `local-args` are arguments for the client where it is running, `server` +is the connect string, and `remote-args` and `job file(s)` are sent to the +server. The `server` string follows the same format as it does on the server +side, to allow IP/hostname/socket and port strings. + +Fio can connect to multiple servers this way:: + + fio --client= --client= + +If the job file is located on the fio server, then you can tell the server to +load a local file as well. This is done by using :option:`--remote-config` :: + + fio --client=server --remote-config /path/to/file.fio + +Then fio will open this local (to the server) job file instead of being passed +one from the client. + +If you have many servers (example: 100 VMs/containers), you can input a pathname +of a file containing host IPs/names as the parameter value for the +:option:`--client` option. For example, here is an example :file:`host.list` +file containing 2 hostnames:: + + host1.your.dns.domain + host2.your.dns.domain + +The fio command would then be:: + + fio --client=host.list + +In this mode, you cannot input server-specific parameters or job files -- all +servers receive the same job file. + +In order to let ``fio --client`` runs use a shared filesystem from multiple +hosts, ``fio --client`` now prepends the IP address of the server to the +filename. For example, if fio is using directory :file:`/mnt/nfs/fio` and is +writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile` +containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and +192.168.10.121, then fio will create two files:: + + /mnt/nfs/fio/192.168.10.120.fileio.tmp + /mnt/nfs/fio/192.168.10.121.fileio.tmp diff --git a/HOWTO.rst b/HOWTO.rst deleted file mode 100644 index d63fff7c..00000000 --- a/HOWTO.rst +++ /dev/null @@ -1,3375 +0,0 @@ -How fio works -------------- - -The first step in getting fio to simulate a desired I/O workload, is writing a -job file describing that specific setup. A job file may contain any number of -threads and/or files -- the typical contents of the job file is a *global* -section defining shared parameters, and one or more job sections describing the -jobs involved. When run, fio parses this file and sets everything up as -described. If we break down a job from top to bottom, it contains the following -basic parameters: - -`I/O type`_ - - Defines the I/O pattern issued to the file(s). We may only be reading - sequentially from this file(s), or we may be writing randomly. Or even - mixing reads and writes, sequentially or randomly. - Should we be doing buffered I/O, or direct/raw I/O? - -`Block size`_ - - In how large chunks are we issuing I/O? This may be a single value, - or it may describe a range of block sizes. - -`I/O size`_ - - How much data are we going to be reading/writing. - -`I/O engine`_ - - How do we issue I/O? We could be memory mapping the file, we could be - using regular read/write, we could be using splice, async I/O, or even - SG (SCSI generic sg). - -`I/O depth`_ - - If the I/O engine is async, how large a queuing depth do we want to - maintain? - - -`Target file/device`_ - - How many files are we spreading the workload over. - -`Threads, processes and job synchronization`_ - - How many threads or processes should we spread this workload over. - -The above are the basic parameters defined for a workload, in addition there's a -multitude of parameters that modify other aspects of how this job behaves. - - -Command line options --------------------- - -.. option:: --debug=type - - Enable verbose tracing of various fio actions. May be ``all`` for all types - or individual types separated by a comma (eg ``--debug=file,mem`` will - enable file and memory debugging). Currently, additional logging is - available for: - - *process* - Dump info related to processes. - *file* - Dump info related to file actions. - *io* - Dump info related to I/O queuing. - *mem* - Dump info related to memory allocations. - *blktrace* - Dump info related to blktrace setup. - *verify* - Dump info related to I/O verification. - *all* - Enable all debug options. - *random* - Dump info related to random offset generation. - *parse* - Dump info related to option matching and parsing. - *diskutil* - Dump info related to disk utilization updates. - *job:x* - Dump info only related to job number x. - *mutex* - Dump info only related to mutex up/down ops. - *profile* - Dump info related to profile extensions. - *time* - Dump info related to internal time keeping. - *net* - Dump info related to networking connections. - *rate* - Dump info related to I/O rate switching. - *compress* - Dump info related to log compress/decompress. - *?* or *help* - Show available debug options. - -.. option:: --parse-only - - Parse options only, don\'t start any I/O. - -.. option:: --output=filename - - Write output to file `filename`. - -.. option:: --bandwidth-log - - Generate aggregate bandwidth logs. - -.. option:: --minimal - - Print statistics in a terse, semicolon-delimited format. - -.. option:: --append-terse - - Print statistics in selected mode AND terse, semicolon-delimited format. - **deprecated**, use :option:`--output-format` instead to select multiple - formats. - -.. option:: --output-format=type - - Set the reporting format to `normal`, `terse`, `json`, or `json+`. Multiple - formats can be selected, separate by a comma. `terse` is a CSV based - format. `json+` is like `json`, except it adds a full dump of the latency - buckets. - -.. option:: --terse-version=type - - Set terse version output format (default 3, or 2 or 4). - -.. option:: --version - - Print version info and exit. - -.. option:: --help - - Print this page. - -.. option:: --cpuclock-test - - Perform test and validation of internal CPU clock. - -.. option:: --crctest=test - - Test the speed of the builtin checksumming functions. If no argument is - given, all of them are tested. Or a comma separated list can be passed, in - which case the given ones are tested. - -.. option:: --cmdhelp=command - - Print help information for `command`. May be ``all`` for all commands. - -.. option:: --enghelp=[ioengine[,command]] - - List all commands defined by :option:`ioengine`, or print help for `command` - defined by :option:`ioengine`. If no :option:`ioengine` is given, list all - available ioengines. - -.. option:: --showcmd=jobfile - - Turn a job file into command line options. - -.. option:: --readonly - - Turn on safety read-only checks, preventing writes. The ``--readonly`` - option is an extra safety guard to prevent users from accidentally starting - a write workload when that is not desired. Fio will only write if - `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used - as an extra precaution as ``--readonly`` will also enable a write check in - the I/O engine core to prevent writes due to unknown user space bug(s). - -.. option:: --eta=when - - When real-time ETA estimate should be printed. May be `always`, `never` or - `auto`. - -.. option:: --eta-newline=time - - Force a new line for every `time` period passed. - -.. option:: --status-interval=time - - Force full status dump every `time` period passed. - -.. option:: --section=name - - Only run specified section in job file. Multiple sections can be specified. - The ``--section`` option allows one to combine related jobs into one file. - E.g. one job file could define light, moderate, and heavy sections. Tell - fio to run only the "heavy" section by giving ``--section=heavy`` - command line option. One can also specify the "write" operations in one - section and "verify" operation in another section. The ``--section`` option - only applies to job sections. The reserved *global* section is always - parsed and used. - -.. option:: --alloc-size=kb - - Set the internal smalloc pool to this size in kb (def 1024). The - ``--alloc-size`` switch allows one to use a larger pool size for smalloc. - If running large jobs with randommap enabled, fio can run out of memory. - Smalloc is an internal allocator for shared structures from a fixed size - memory pool. The pool size defaults to 16M and can grow to 8 pools. - - NOTE: While running :file:`.fio_smalloc.*` backing store files are visible - in :file:`/tmp`. - -.. option:: --warnings-fatal - - All fio parser warnings are fatal, causing fio to exit with an - error. - -.. option:: --max-jobs=nr - - Maximum number of threads/processes to support. - -.. option:: --server=args - - Start a backend server, with `args` specifying what to listen to. - See `Client/Server`_ section. - -.. option:: --daemonize=pidfile - - Background a fio server, writing the pid to the given `pidfile` file. - -.. option:: --client=hostname - - Instead of running the jobs locally, send and run them on the given host or - set of hosts. See `Client/Server`_ section. - -.. option:: --remote-config=file - - Tell fio server to load this local file. - -.. option:: --idle-prof=option - - Report cpu idleness on a system or percpu basis - ``--idle-prof=system,percpu`` or - run unit work calibration only ``--idle-prof=calibrate``. - -.. option:: --inflate-log=log - - Inflate and output compressed log. - -.. option:: --trigger-file=file - - Execute trigger cmd when file exists. - -.. option:: --trigger-timeout=t - - Execute trigger at this time. - -.. option:: --trigger=cmd - - Set this command as local trigger. - -.. option:: --trigger-remote=cmd - - Set this command as remote trigger. - -.. option:: --aux-path=path - - Use this path for fio state generated files. - -Any parameters following the options will be assumed to be job files, unless -they match a job file parameter. Multiple job files can be listed and each job -file will be regarded as a separate group. Fio will :option:`stonewall` -execution between each group. - - -Job file format ---------------- - -As previously described, fio accepts one or more job files describing what it is -supposed to do. The job file format is the classic ini file, where the names -enclosed in [] brackets define the job name. You are free to use any ascii name -you want, except *global* which has special meaning. Following the job name is -a sequence of zero or more parameters, one per line, that define the behavior of -the job. If the first character in a line is a ';' or a '#', the entire line is -discarded as a comment. - -A *global* section sets defaults for the jobs described in that file. A job may -override a *global* section parameter, and a job file may even have several -*global* sections if so desired. A job is only affected by a *global* section -residing above it. - -The :option:`--cmdhelp` option also lists all options. If used with an `option` -argument, :option:`--cmdhelp` will detail the given `option`. - -See the `examples/` directory for inspiration on how to write job files. Note -the copyright and license requirements currently apply to `examples/` files. - -So let's look at a really simple job file that defines two processes, each -randomly reading from a 128MiB file: - -.. code-block:: ini - - ; -- start job file -- - [global] - rw=randread - size=128m - - [job1] - - [job2] - - ; -- end job file -- - -As you can see, the job file sections themselves are empty as all the described -parameters are shared. As no :option:`filename` option is given, fio makes up a -`filename` for each of the jobs as it sees fit. On the command line, this job -would look as follows:: - -$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2 - - -Let's look at an example that has a number of processes writing randomly to -files: - -.. code-block:: ini - - ; -- start job file -- - [random-writers] - ioengine=libaio - iodepth=4 - rw=randwrite - bs=32k - direct=0 - size=64m - numjobs=4 - ; -- end job file -- - -Here we have no *global* section, as we only have one job defined anyway. We -want to use async I/O here, with a depth of 4 for each file. We also increased -the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical -jobs. The result is 4 processes each randomly writing to their own 64MiB -file. Instead of using the above job file, you could have given the parameters -on the command line. For this case, you would specify:: - -$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4 - -When fio is utilized as a basis of any reasonably large test suite, it might be -desirable to share a set of standardized settings across multiple job files. -Instead of copy/pasting such settings, any section may pull in an external -:file:`filename.fio` file with *include filename* directive, as in the following -example:: - - ; -- start job file including.fio -- - [global] - filename=/tmp/test - filesize=1m - include glob-include.fio - - [test] - rw=randread - bs=4k - time_based=1 - runtime=10 - include test-include.fio - ; -- end job file including.fio -- - -.. code-block:: ini - - ; -- start job file glob-include.fio -- - thread=1 - group_reporting=1 - ; -- end job file glob-include.fio -- - -.. code-block:: ini - - ; -- start job file test-include.fio -- - ioengine=libaio - iodepth=4 - ; -- end job file test-include.fio -- - -Settings pulled into a section apply to that section only (except *global* -section). Include directives may be nested in that any included file may contain -further include directive(s). Include files may not contain [] sections. - - -Environment variables -~~~~~~~~~~~~~~~~~~~~~ - -Fio also supports environment variable expansion in job files. Any sub-string of -the form ``${VARNAME}`` as part of an option value (in other words, on the right -of the '='), will be expanded to the value of the environment variable called -`VARNAME`. If no such environment variable is defined, or `VARNAME` is the -empty string, the empty string will be substituted. - -As an example, let's look at a sample fio invocation and job file:: - -$ SIZE=64m NUMJOBS=4 fio jobfile.fio - -.. code-block:: ini - - ; -- start job file -- - [random-writers] - rw=randwrite - size=${SIZE} - numjobs=${NUMJOBS} - ; -- end job file -- - -This will expand to the following equivalent job file at runtime: - -.. code-block:: ini - - ; -- start job file -- - [random-writers] - rw=randwrite - size=64m - numjobs=4 - ; -- end job file -- - -Fio ships with a few example job files, you can also look there for inspiration. - -Reserved keywords -~~~~~~~~~~~~~~~~~ - -Additionally, fio has a set of reserved keywords that will be replaced -internally with the appropriate value. Those keywords are: - -**$pagesize** - - The architecture page size of the running system. - -**$mb_memory** - - Megabytes of total memory in the system. - -**$ncpus** - - Number of online available CPUs. - -These can be used on the command line or in the job file, and will be -automatically substituted with the current system values when the job is -run. Simple math is also supported on these keywords, so you can perform actions -like:: - - size=8*$mb_memory - -and get that properly expanded to 8 times the size of memory in the machine. - - -Job file parameters -------------------- - -This section describes in details each parameter associated with a job. Some -parameters take an option of a given type, such as an integer or a -string. Anywhere a numeric value is required, an arithmetic expression may be -used, provided it is surrounded by parentheses. Supported operators are: - - - addition (+) - - subtraction (-) - - multiplication (*) - - division (/) - - modulus (%) - - exponentiation (^) - -For time values in expressions, units are microseconds by default. This is -different than for time values not in expressions (not enclosed in -parentheses). The following types are used: - - -Parameter types -~~~~~~~~~~~~~~~ - -**str** - String. This is a sequence of alpha characters. - -**time** - Integer with possible time suffix. In seconds unless otherwise - specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds, minutes, - and hours, and accepts 'ms' (or 'msec') for milliseconds, and 'us' (or - 'usec') for microseconds. - -.. _int: - -**int** - Integer. A whole number value, which may contain an integer prefix - and an integer suffix: - - [*integer prefix*] **number** [*integer suffix*] - - The optional *integer prefix* specifies the number's base. The default - is decimal. *0x* specifies hexadecimal. - - The optional *integer suffix* specifies the number's units, and includes an - optional unit prefix and an optional unit. For quantities of data, the - default unit is bytes. For quantities of time, the default unit is seconds. - - With :option:`kb_base` =1000, fio follows international standards for unit - prefixes. To specify power-of-10 decimal values defined in the - International System of Units (SI): - - * *Ki* -- means kilo (K) or 1000 - * *Mi* -- means mega (M) or 1000**2 - * *Gi* -- means giga (G) or 1000**3 - * *Ti* -- means tera (T) or 1000**4 - * *Pi* -- means peta (P) or 1000**5 - - To specify power-of-2 binary values defined in IEC 80000-13: - - * *k* -- means kibi (Ki) or 1024 - * *M* -- means mebi (Mi) or 1024**2 - * *G* -- means gibi (Gi) or 1024**3 - * *T* -- means tebi (Ti) or 1024**4 - * *P* -- means pebi (Pi) or 1024**5 - - With :option:`kb_base` =1024 (the default), the unit prefixes are opposite - from those specified in the SI and IEC 80000-13 standards to provide - compatibility with old scripts. For example, 4k means 4096. - - For quantities of data, an optional unit of 'B' may be included - (e.g., 'kB' is the same as 'k'). - - The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega, - not milli). 'b' and 'B' both mean byte, not bit. - - Examples with :option:`kb_base` =1000: - - * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB - * *1 MiB*: 1048576, 1mi, 1024ki - * *1 MB*: 1000000, 1m, 1000k - * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi - * *1 TB*: 1000000000, 1t, 1000m, 1000000k - - Examples with :option:`kb_base` =1024 (default): - - * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB - * *1 MiB*: 1048576, 1m, 1024k - * *1 MB*: 1000000, 1mi, 1000ki - * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m - * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki - - To specify times (units are not case sensitive): - - * *D* -- means days - * *H* -- means hours - * *M* -- mean minutes - * *s* -- or sec means seconds (default) - * *ms* -- or *msec* means milliseconds - * *us* -- or *usec* means microseconds - - If the option accepts an upper and lower range, use a colon ':' or - minus '-' to separate such values. See :ref:`irange `. - -.. _bool: - -**bool** - Boolean. Usually parsed as an integer, however only defined for - true and false (1 and 0). - -.. _irange: - -**irange** - Integer range with suffix. Allows value range to be given, such as - 1024-4096. A colon may also be used as the separator, eg 1k:4k. If the - option allows two sets of ranges, they can be specified with a ',' or '/' - delimiter: 1k-4k/8k-32k. Also see :ref:`int `. - -**float_list** - A list of floating point numbers, separated by a ':' character. - - -Units -~~~~~ - -.. option:: kb_base=int - - Select the interpretation of unit prefixes in input parameters. - - **1000** - Inputs comply with IEC 80000-13 and the International - System of Units (SI). Use: - - - power-of-2 values with IEC prefixes (e.g., KiB) - - power-of-10 values with SI prefixes (e.g., kB) - - **1024** - Compatibility mode (default). To avoid breaking old scripts: - - - power-of-2 values with SI prefixes - - power-of-10 values with IEC prefixes - - See :option:`bs` for more details on input parameters. - - Outputs always use correct prefixes. Most outputs include both - side-by-side, like:: - - bw=2383.3kB/s (2327.4KiB/s) - - If only one value is reported, then kb_base selects the one to use: - - **1000** -- SI prefixes - - **1024** -- IEC prefixes - -.. option:: unit_base=int - - Base unit for reporting. Allowed values are: - - **0** - Use auto-detection (default). - **8** - Byte based. - **1** - Bit based. - - -With the above in mind, here follows the complete list of fio job parameters. - - -Job description -~~~~~~~~~~~~~~~ - -.. option:: name=str - - ASCII name of the job. This may be used to override the name printed by fio - for this job. Otherwise the job name is used. On the command line this - parameter has the special purpose of also signaling the start of a new job. - -.. option:: description=str - - Text description of the job. Doesn't do anything except dump this text - description when this job is run. It's not parsed. - -.. option:: loops=int - - Run the specified number of iterations of this job. Used to repeat the same - workload a given number of times. Defaults to 1. - -.. option:: numjobs=int - - Create the specified number of clones of this job. May be used to setup a - larger number of threads/processes doing the same thing. Each thread is - reported separately; to see statistics for all clones as a whole, use - :option:`group_reporting` in conjunction with :option:`new_group`. - See :option:`--max-jobs`. - - -Time related parameters -~~~~~~~~~~~~~~~~~~~~~~~ - -.. option:: runtime=time - - Tell fio to terminate processing after the specified number of seconds. It - can be quite hard to determine for how long a specified job will run, so - this parameter is handy to cap the total runtime to a given time. - -.. option:: time_based - - If set, fio will run for the duration of the :option:`runtime` specified - even if the file(s) are completely read or written. It will simply loop over - the same workload as many times as the :option:`runtime` allows. - -.. option:: startdelay=irange - - Delay start of job for the specified number of seconds. Supports all time - suffixes to allow specification of hours, minutes, seconds and milliseconds - -- seconds are the default if a unit is omitted. Can be given as a range - which causes each thread to choose randomly out of the range. - -.. option:: ramp_time=time - - If set, fio will run the specified workload for this amount of time before - logging any performance numbers. Useful for letting performance settle - before logging results, thus minimizing the runtime required for stable - results. Note that the ``ramp_time`` is considered lead in time for a job, - thus it will increase the total runtime if a special timeout or - :option:`runtime` is specified. - -.. option:: clocksource=str - - Use the given clocksource as the base of timing. The supported options are: - - **gettimeofday** - :manpage:`gettimeofday(2)` - - **clock_gettime** - :manpage:`clock_gettime(2)` - - **cpu** - Internal CPU clock source - - cpu is the preferred clocksource if it is reliable, as it is very fast (and - fio is heavy on time calls). Fio will automatically use this clocksource if - it's supported and considered reliable on the system it is running on, - unless another clocksource is specifically set. For x86/x86-64 CPUs, this - means supporting TSC Invariant. - -.. option:: gtod_reduce=bool - - Enable all of the :manpage:`gettimeofday(2)` reducing options - (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw`) plus - reduce precision of the timeout somewhat to really shrink the - :manpage:`gettimeofday(2)` call count. With this option enabled, we only do - about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all - time keeping was enabled. - -.. option:: gtod_cpu=int - - Sometimes it's cheaper to dedicate a single thread of execution to just - getting the current time. Fio (and databases, for instance) are very - intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set - one CPU aside for doing nothing but logging current time to a shared memory - location. Then the other threads/processes that run I/O workloads need only - copy that segment, instead of entering the kernel with a - :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time - calls will be excluded from other uses. Fio will manually clear it from the - CPU mask of other jobs. - - -Target file/device -~~~~~~~~~~~~~~~~~~ - -.. option:: directory=str - - Prefix filenames with this directory. Used to place files in a different - location than :file:`./`. You can specify a number of directories by - separating the names with a ':' character. These directories will be - assigned equally distributed to job clones creates with :option:`numjobs` as - long as they are using generated filenames. If specific `filename(s)` are - set fio will use the first listed directory, and thereby matching the - `filename` semantic which generates a file each clone if not specified, but - let all clones use the same if set. - - See the :option:`filename` option for escaping certain characters. - -.. option:: filename=str - - Fio normally makes up a `filename` based on the job name, thread number, and - file number. If you want to share files between threads in a job or several - jobs, specify a `filename` for each of them to override the default. If the - ioengine is file based, you can specify a number of files by separating the - names with a ':' colon. So if you wanted a job to open :file:`/dev/sda` and - :file:`/dev/sdb` as the two working files, you would use - ``filename=/dev/sda:/dev/sdb``. - On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for - the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc. - Note: Windows and FreeBSD prevent write access to areas - of the disk containing in-use data (e.g. filesystems). If the wanted - `filename` does need to include a colon, then escape that with a ``\`` - character. For instance, if the `filename` is :file:`/dev/dsk/foo@3,0:c`, - then you would use ``filename="/dev/dsk/foo@3,0\:c"``. The - :file:`-` is a reserved name, meaning stdin or stdout. Which of the two - depends on the read/write direction set. - -.. option:: filename_format=str - - If sharing multiple files between jobs, it is usually necessary to have fio - generate the exact names that you want. By default, fio will name a file - based on the default file format specification of - :file:`jobname.jobnumber.filenumber`. With this option, that can be - customized. Fio will recognize and replace the following keywords in this - string: - - **$jobname** - The name of the worker thread or process. - **$jobnum** - The incremental number of the worker thread or process. - **$filenum** - The incremental number of the file for that worker thread or - process. - - To have dependent jobs share a set of files, this option can be set to have - fio generate filenames that are shared between the two. For instance, if - :file:`testfiles.$filenum` is specified, file number 4 for any job will be - named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum` - will be used if no other format specifier is given. - -.. option:: unique_filename=bool - - To avoid collisions between networked clients, fio defaults to prefixing any - generated filenames (with a directory specified) with the source of the - client connecting. To disable this behavior, set this option to 0. - -.. option:: opendir=str - - Recursively open any files below directory `str`. - -.. option:: lockfile=str - - Fio defaults to not locking any files before it does I/O to them. If a file - or file descriptor is shared, fio can serialize I/O to that file to make the - end result consistent. This is usual for emulating real workloads that share - files. The lock modes are: - - **none** - No locking. The default. - **exclusive** - Only one thread or process may do I/O at a time, excluding all - others. - **readwrite** - Read-write locking on the file. Many readers may - access the file at the same time, but writes get exclusive access. - -.. option:: nrfiles=int - - Number of files to use for this job. Defaults to 1. - -.. option:: openfiles=int - - Number of files to keep open at the same time. Defaults to the same as - :option:`nrfiles`, can be set smaller to limit the number simultaneous - opens. - -.. option:: file_service_type=str - - Defines how fio decides which file from a job to service next. The following - types are defined: - - **random** - Choose a file at random. - - **roundrobin** - Round robin over opened files. This is the default. - - **sequential** - Finish one file before moving on to the next. Multiple files can - still be open depending on 'openfiles'. - - **zipf** - Use a *zipfian* distribution to decide what file to access. - - **pareto** - Use a *pareto* distribution to decide what file to access. - - **gauss** - Use a *gaussian* (normal) distribution to decide what file to - access. - - For *random*, *roundrobin*, and *sequential*, a postfix can be appended to - tell fio how many I/Os to issue before switching to a new file. For example, - specifying ``file_service_type=random:8`` would cause fio to issue - 8 I/Os before selecting a new file at random. For the non-uniform - distributions, a floating point postfix can be given to influence how the - distribution is skewed. See :option:`random_distribution` for a description - of how that would work. - -.. option:: ioscheduler=str - - Attempt to switch the device hosting the file to the specified I/O scheduler - before running. - -.. option:: create_serialize=bool - - If true, serialize the file creation for the jobs. This may be handy to - avoid interleaving of data files, which may greatly depend on the filesystem - used and even the number of processors in the system. - -.. option:: create_fsync=bool - - fsync the data file after creation. This is the default. - -.. option:: create_on_open=bool - - Don't pre-setup the files for I/O, just create open() when it's time to do - I/O to that file. - -.. option:: create_only=bool - - If true, fio will only run the setup phase of the job. If files need to be - laid out or updated on disk, only that will be done. The actual job contents - are not executed. - -.. option:: allow_file_create=bool - - If true, fio is permitted to create files as part of its workload. This is - the default behavior. If this option is false, then fio will error out if - the files it needs to use don't already exist. Default: true. - -.. option:: allow_mounted_write=bool - - If this isn't set, fio will abort jobs that are destructive (eg that write) - to what appears to be a mounted device or partition. This should help catch - creating inadvertently destructive tests, not realizing that the test will - destroy data on the mounted file system. Default: false. - -.. option:: pre_read=bool - - If this is given, files will be pre-read into memory before starting the - given I/O operation. This will also clear the :option:`invalidate` flag, - since it is pointless to pre-read and then drop the cache. This will only - work for I/O engines that are seek-able, since they allow you to read the - same data multiple times. Thus it will not work on eg network or splice I/O. - -.. option:: unlink=bool - - Unlink the job files when done. Not the default, as repeated runs of that - job would then waste time recreating the file set again and again. - -.. option:: unlink_each_loop=bool - - Unlink job files after each iteration or loop. - -.. option:: zonesize=int - - Divide a file into zones of the specified size. See :option:`zoneskip`. - -.. option:: zonerange=int - - Give size of an I/O zone. See :option:`zoneskip`. - -.. option:: zoneskip=int - - Skip the specified number of bytes when :option:`zonesize` data has been - read. The two zone options can be used to only do I/O on zones of a file. - - -I/O type -~~~~~~~~ - -.. option:: direct=bool - - If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that - ZFS on Solaris doesn't support direct I/O. On Windows the synchronous - ioengines don't support direct I/O. Default: false. - -.. option:: atomic=bool - - If value is true, attempt to use atomic direct I/O. Atomic writes are - guaranteed to be stable once acknowledged by the operating system. Only - Linux supports O_ATOMIC right now. - -.. option:: buffered=bool - - If value is true, use buffered I/O. This is the opposite of the - :option:`direct` option. Defaults to true. - -.. option:: readwrite=str, rw=str - - Type of I/O pattern. Accepted values are: - - **read** - Sequential reads. - **write** - Sequential writes. - **trim** - Sequential trims (Linux block devices only). - **randwrite** - Random writes. - **randread** - Random reads. - **randtrim** - Random trims (Linux block devices only). - **rw,readwrite** - Sequential mixed reads and writes. - **randrw** - Random mixed reads and writes. - **trimwrite** - Sequential trim+write sequences. Blocks will be trimmed first, - then the same blocks will be written to. - - Fio defaults to read if the option is not specified. For the mixed I/O - types, the default is to split them 50/50. For certain types of I/O the - result may still be skewed a bit, since the speed may be different. It is - possible to specify a number of I/O's to do before getting a new offset, - this is done by appending a ``:`` to the end of the string given. For a - random read, it would look like ``rw=randread:8`` for passing in an offset - modifier with a value of 8. If the suffix is used with a sequential I/O - pattern, then the value specified will be added to the generated offset for - each I/O. For instance, using ``rw=write:4k`` will skip 4k for every - write. It turns sequential I/O into sequential I/O with holes. See the - :option:`rw_sequencer` option. - -.. option:: rw_sequencer=str - - If an offset modifier is given by appending a number to the ``rw=`` - line, then this option controls how that number modifies the I/O offset - being generated. Accepted values are: - - **sequential** - Generate sequential offset. - **identical** - Generate the same offset. - - ``sequential`` is only useful for random I/O, where fio would normally - generate a new random offset for every I/O. If you append eg 8 to randread, - you would get a new random offset for every 8 I/O's. The result would be a - seek for only every 8 I/O's, instead of for every I/O. Use ``rw=randread:8`` - to specify that. As sequential I/O is already sequential, setting - ``sequential`` for that would not result in any differences. ``identical`` - behaves in a similar fashion, except it sends the same offset 8 number of - times before generating a new offset. - -.. option:: unified_rw_reporting=bool - - Fio normally reports statistics on a per data direction basis, meaning that - reads, writes, and trims are accounted and reported separately. If this - option is set fio sums the results and report them as "mixed" instead. - -.. option:: randrepeat=bool - - Seed the random number generator used for random I/O patterns in a - predictable way so the pattern is repeatable across runs. Default: true. - -.. option:: allrandrepeat=bool - - Seed all random number generators in a predictable way so results are - repeatable across runs. Default: false. - -.. option:: randseed=int - - Seed the random number generators based on this seed value, to be able to - control what sequence of output is being generated. If not set, the random - sequence depends on the :option:`randrepeat` setting. - -.. option:: fallocate=str - - Whether pre-allocation is performed when laying down files. - Accepted values are: - - **none** - Do not pre-allocate space. - - **posix** - Pre-allocate via :manpage:`posix_fallocate(3)`. - - **keep** - Pre-allocate via :manpage:`fallocate(2)` with - FALLOC_FL_KEEP_SIZE set. - - **0** - Backward-compatible alias for **none**. - - **1** - Backward-compatible alias for **posix**. - - May not be available on all supported platforms. **keep** is only available - on Linux. If using ZFS on Solaris this must be set to **none** because ZFS - doesn't support it. Default: **posix**. - -.. option:: fadvise_hint=str - - Use :manpage:`posix_fadvise(2)` to advise the kernel on what I/O patterns - are likely to be issued. Accepted values are: - - **0** - Backwards-compatible hint for "no hint". - - **1** - Backwards compatible hint for "advise with fio workload type". This - uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL** - for a sequential workload. - - **sequential** - Advise using **FADV_SEQUENTIAL**. - - **random** - Advise using **FADV_RANDOM**. - -.. option:: fadvise_stream=int - - Use :manpage:`posix_fadvise(2)` to advise the kernel what stream ID the - writes issued belong to. Only supported on Linux. Note, this option may - change going forward. - -.. option:: offset=int - - Start I/O at the given offset in the file. The data before the given offset - will not be touched. This effectively caps the file size at `real_size - - offset`. - -.. option:: offset_increment=int - - If this is provided, then the real offset becomes `offset + offset_increment - * thread_number`, where the thread number is a counter that starts at 0 and - is incremented for each sub-job (i.e. when :option:`numjobs` option is - specified). This option is useful if there are several jobs which are - intended to operate on a file in parallel disjoint segments, with even - spacing between the starting points. - -.. option:: number_ios=int - - Fio will normally perform IOs until it has exhausted the size of the region - set by :option:`size`, or if it exhaust the allocated time (or hits an error - condition). With this setting, the range/size can be set independently of - the number of IOs to perform. When fio reaches this number, it will exit - normally and report status. Note that this does not extend the amount of I/O - that will be done, it will only stop fio if this condition is met before - other end-of-job criteria. - -.. option:: fsync=int - - If writing to a file, issue a sync of the dirty data for every number of - blocks given. For example, if you give 32 as a parameter, fio will sync the - file for every 32 writes issued. If fio is using non-buffered I/O, we may - not sync the file. The exception is the sg I/O engine, which synchronizes - the disk cache anyway. - -.. option:: fdatasync=int - - Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and - not metadata blocks. In FreeBSD and Windows there is no - :manpage:`fdatasync(2)`, this falls back to using :manpage:`fsync(2)`. - -.. option:: write_barrier=int - - Make every `N-th` write a barrier write. - -.. option:: sync_file_range=str:val - - Use :manpage:`sync_file_range(2)` for every `val` number of write - operations. Fio will track range of writes that have happened since the last - :manpage:`sync_file_range(2)` call. `str` can currently be one or more of: - - **wait_before** - SYNC_FILE_RANGE_WAIT_BEFORE - **write** - SYNC_FILE_RANGE_WRITE - **wait_after** - SYNC_FILE_RANGE_WAIT_AFTER - - So if you do ``sync_file_range=wait_before,write:8``, fio would use - ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8 - writes. Also see the :manpage:`sync_file_range(2)` man page. This option is - Linux specific. - -.. option:: overwrite=bool - - If true, writes to a file will always overwrite existing data. If the file - doesn't already exist, it will be created before the write phase begins. If - the file exists and is large enough for the specified write phase, nothing - will be done. - -.. option:: end_fsync=bool - - If true, fsync file contents when a write stage has completed. - -.. option:: fsync_on_close=bool - - If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs - from end_fsync in that it will happen on every file close, not just at the - end of the job. - -.. option:: rwmixread=int - - Percentage of a mixed workload that should be reads. Default: 50. - -.. option:: rwmixwrite=int - - Percentage of a mixed workload that should be writes. If both - :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not - add up to 100%, the latter of the two will be used to override the - first. This may interfere with a given rate setting, if fio is asked to - limit reads or writes to a certain rate. If that is the case, then the - distribution may be skewed. Default: 50. - -.. option:: random_distribution=str:float[,str:float][,str:float] - - By default, fio will use a completely uniform random distribution when asked - to perform random I/O. Sometimes it is useful to skew the distribution in - specific ways, ensuring that some parts of the data is more hot than others. - fio includes the following distribution models: - - **random** - Uniform random distribution - - **zipf** - Zipf distribution - - **pareto** - Pareto distribution - - **gauss** - Normal (gaussian) distribution - - **zoned** - Zoned random distribution - - When using a **zipf** or **pareto** distribution, an input value is also - needed to define the access pattern. For **zipf**, this is the `zipf - theta`. For **pareto**, it's the `pareto power`. Fio includes a test - program, :command:`genzipf`, that can be used visualize what the given input - values will yield in terms of hit rates. If you wanted to use **zipf** with - a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the - option. If a non-uniform model is used, fio will disable use of the random - map. For the **gauss** distribution, a normal deviation is supplied as a - value between 0 and 100. - - For a **zoned** distribution, fio supports specifying percentages of I/O - access that should fall within what range of the file or device. For - example, given a criteria of: - - * 60% of accesses should be to the first 10% - * 30% of accesses should be to the next 20% - * 8% of accesses should be to to the next 30% - * 2% of accesses should be to the next 40% - - we can define that through zoning of the random accesses. For the above - example, the user would do:: - - random_distribution=zoned:60/10:30/20:8/30:2/40 - - similarly to how :option:`bssplit` works for setting ranges and percentages - of block sizes. Like :option:`bssplit`, it's possible to specify separate - zones for reads, writes, and trims. If just one set is given, it'll apply to - all of them. - -.. option:: percentage_random=int[,int][,int] - - For a random workload, set how big a percentage should be random. This - defaults to 100%, in which case the workload is fully random. It can be set - from anywhere from 0 to 100. Setting it to 0 would make the workload fully - sequential. Any setting in between will result in a random mix of sequential - and random I/O, at the given percentages. Comma-separated values may be - specified for reads, writes, and trims as described in :option:`blocksize`. - -.. option:: norandommap - - Normally fio will cover every block of the file when doing random I/O. If - this option is given, fio will just get a new random offset without looking - at past I/O history. This means that some blocks may not be read or written, - and that some blocks may be read/written more than once. If this option is - used with :option:`verify` and multiple blocksizes (via :option:`bsrange`), - only intact blocks are verified, i.e., partially-overwritten blocks are - ignored. - -.. option:: softrandommap=bool - - See :option:`norandommap`. If fio runs with the random block map enabled and - it fails to allocate the map, if this option is set it will continue without - a random block map. As coverage will not be as complete as with random maps, - this option is disabled by default. - -.. option:: random_generator=str - - Fio supports the following engines for generating - I/O offsets for random I/O: - - **tausworthe** - Strong 2^88 cycle random number generator - **lfsr** - Linear feedback shift register generator - **tausworthe64** - Strong 64-bit 2^258 cycle random number generator - - **tausworthe** is a strong random number generator, but it requires tracking - on the side if we want to ensure that blocks are only read or written - once. **LFSR** guarantees that we never generate the same offset twice, and - it's also less computationally expensive. It's not a true random generator, - however, though for I/O purposes it's typically good enough. **LFSR** only - works with single block sizes, not with workloads that use multiple block - sizes. If used with such a workload, fio may read or write some blocks - multiple times. The default value is **tausworthe**, unless the required - space exceeds 2^32 blocks. If it does, then **tausworthe64** is - selected automatically. - - -Block size -~~~~~~~~~~ - -.. option:: blocksize=int[,int][,int], bs=int[,int][,int] - - The block size in bytes used for I/O units. Default: 4096. A single value - applies to reads, writes, and trims. Comma-separated values may be - specified for reads, writes, and trims. A value not terminated in a comma - applies to subsequent types. - - Examples: - - **bs=256k** - means 256k for reads, writes and trims. - - **bs=8k,32k** - means 8k for reads, 32k for writes and trims. - - **bs=8k,32k,** - means 8k for reads, 32k for writes, and default for trims. - - **bs=,8k** - means default for reads, 8k for writes and trims. - - **bs=,8k,** - means default for reads, 8k for writes, and default for writes. - -.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange] - - A range of block sizes in bytes for I/O units. The issued I/O unit will - always be a multiple of the minimum size, unless - :option:`blocksize_unaligned` is set. - - Comma-separated ranges may be specified for reads, writes, and trims as - described in :option:`blocksize`. - - Example: ``bsrange=1k-4k,2k-8k``. - -.. option:: bssplit=str[,str][,str] - - Sometimes you want even finer grained control of the block sizes issued, not - just an even split between them. This option allows you to weight various - block sizes, so that you are able to define a specific amount of block sizes - issued. The format for this option is:: - - bssplit=blocksize/percentage:blocksize/percentage - - for as many block sizes as needed. So if you want to define a workload that - has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would write:: - - bssplit=4k/10:64k/50:32k/40 - - Ordering does not matter. If the percentage is left blank, fio will fill in - the remaining values evenly. So a bssplit option like this one:: - - bssplit=4k/50:1k/:32k/ - - would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always add up - to 100, if bssplit is given a range that adds up to more, it will error out. - - Comma-separated values may be specified for reads, writes, and trims as - described in :option:`blocksize`. - - If you want a workload that has 50% 2k reads and 50% 4k reads, while having - 90% 4k writes and 10% 8k writes, you would specify:: - - bssplit=2k/50:4k/50,4k/90,8k/10 - -.. option:: blocksize_unaligned, bs_unaligned - - If set, fio will issue I/O units with any size within - :option:`blocksize_range`, not just multiples of the minimum size. This - typically won't work with direct I/O, as that normally requires sector - alignment. - -.. option:: bs_is_seq_rand - - If this option is set, fio will use the normal read,write blocksize settings - as sequential,random blocksize settings instead. Any random read or write - will use the WRITE blocksize settings, and any sequential read or write will - use the READ blocksize settings. - -.. option:: blockalign=int[,int][,int], ba=int[,int][,int] - - Boundary to which fio will align random I/O units. Default: - :option:`blocksize`. Minimum alignment is typically 512b for using direct - I/O, though it usually depends on the hardware block size. This option is - mutually exclusive with using a random map for files, so it will turn off - that option. Comma-separated values may be specified for reads, writes, and - trims as described in :option:`blocksize`. - - -Buffers and memory -~~~~~~~~~~~~~~~~~~ - -.. option:: zero_buffers - - Initialize buffers with all zeros. Default: fill buffers with random data. - -.. option:: refill_buffers - - If this option is given, fio will refill the I/O buffers on every - submit. The default is to only fill it at init time and reuse that - data. Only makes sense if zero_buffers isn't specified, naturally. If data - verification is enabled, `refill_buffers` is also automatically enabled. - -.. option:: scramble_buffers=bool - - If :option:`refill_buffers` is too costly and the target is using data - deduplication, then setting this option will slightly modify the I/O buffer - contents to defeat normal de-dupe attempts. This is not enough to defeat - more clever block compression attempts, but it will stop naive dedupe of - blocks. Default: true. - -.. option:: buffer_compress_percentage=int - - If this is set, then fio will attempt to provide I/O buffer content (on - WRITEs) that compress to the specified level. Fio does this by providing a - mix of random data and a fixed pattern. The fixed pattern is either zeroes, - or the pattern specified by :option:`buffer_pattern`. If the pattern option - is used, it might skew the compression ratio slightly. Note that this is per - block size unit, for file/disk wide compression level that matches this - setting, you'll also want to set :option:`refill_buffers`. - -.. option:: buffer_compress_chunk=int - - See :option:`buffer_compress_percentage`. This setting allows fio to manage - how big the ranges of random data and zeroed data is. Without this set, fio - will provide :option:`buffer_compress_percentage` of blocksize random data, - followed by the remaining zeroed. With this set to some chunk size smaller - than the block size, fio can alternate random and zeroed data throughout the - I/O buffer. - -.. option:: buffer_pattern=str - - If set, fio will fill the I/O buffers with this pattern. If not set, the - contents of I/O buffers is defined by the other options related to buffer - contents. The setting can be any pattern of bytes, and can be prefixed with - 0x for hex values. It may also be a string, where the string must then be - wrapped with ``""``, e.g.:: - - buffer_pattern="abcd" - - or:: - - buffer_pattern=-12 - - or:: - - buffer_pattern=0xdeadface - - Also you can combine everything together in any order:: - - buffer_pattern=0xdeadface"abcd"-12 - -.. option:: dedupe_percentage=int - - If set, fio will generate this percentage of identical buffers when - writing. These buffers will be naturally dedupable. The contents of the - buffers depend on what other buffer compression settings have been set. It's - possible to have the individual buffers either fully compressible, or not at - all. This option only controls the distribution of unique buffers. - -.. option:: invalidate=bool - - Invalidate the buffer/page cache parts for this file prior to starting - I/O. Defaults to true. - -.. option:: sync=bool - - Use synchronous I/O for buffered writes. For the majority of I/O engines, - this means using O_SYNC. Default: false. - -.. option:: iomem=str, mem=str - - Fio can use various types of memory as the I/O unit buffer. The allowed - values are: - - **malloc** - Use memory from :manpage:`malloc(3)` as the buffers. Default memory - type. - - **shm** - Use shared memory as the buffers. Allocated through - :manpage:`shmget(2)`. - - **shmhuge** - Same as shm, but use huge pages as backing. - - **mmap** - Use mmap to allocate buffers. May either be anonymous memory, or can - be file backed if a filename is given after the option. The format - is `mem=mmap:/path/to/file`. - - **mmaphuge** - Use a memory mapped huge file as the buffer backing. Append filename - after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`. - - **mmapshared** - Same as mmap, but use a MMAP_SHARED mapping. - - The area allocated is a function of the maximum allowed bs size for the job, - multiplied by the I/O depth given. Note that for **shmhuge** and - **mmaphuge** to work, the system must have free huge pages allocated. This - can normally be checked and set by reading/writing - :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page - is 4MiB in size. So to calculate the number of huge pages you need for a - given job file, add up the I/O depth of all jobs (normally one unless - :option:`iodepth` is used) and multiply by the maximum bs set. Then divide - that number by the huge page size. You can see the size of the huge pages in - :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero - number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also - see :option:`hugepage-size`. - - **mmaphuge** also needs to have hugetlbfs mounted and the file location - should point there. So if it's mounted in :file:`/huge`, you would use - `mem=mmaphuge:/huge/somefile`. - -.. option:: iomem_align=int - - This indicates the memory alignment of the I/O memory buffers. Note that - the given alignment is applied to the first I/O unit buffer, if using - :option:`iodepth` the alignment of the following buffers are given by the - :option:`bs` used. In other words, if using a :option:`bs` that is a - multiple of the page sized in the system, all buffers will be aligned to - this value. If using a :option:`bs` that is not page aligned, the alignment - of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and - :option:`bs` used. - -.. option:: hugepage-size=int - - Defines the size of a huge page. Must at least be equal to the system - setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably - always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the - preferred way to set this to avoid setting a non-pow-2 bad value. - -.. option:: lockmem=int - - Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to - simulate a smaller amount of memory. The amount specified is per worker. - - -I/O size -~~~~~~~~ - -.. option:: size=int - - The total size of file I/O for this job. Fio will run until this many bytes - has been transferred, unless runtime is limited by other options (such as - :option:`runtime`, for instance, or increased/decreased by - :option:`io_size`). Unless specific :option:`nrfiles` and :option:`filesize` - options are given, fio will divide this size between the available files - specified by the job. If not set, fio will use the full size of the given - files or devices. If the files do not exist, size must be given. It is also - possible to give size as a percentage between 1 and 100. If ``size=20%`` is - given, fio will use 20% of the full size of the given files or devices. - -.. option:: io_size=int, io_limit=int - - Normally fio operates within the region set by :option:`size`, which means - that the :option:`size` option sets both the region and size of I/O to be - performed. Sometimes that is not what you want. With this option, it is - possible to define just the amount of I/O that fio should do. For instance, - if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio - will perform I/O within the first 20GiB but exit when 5GiB have been - done. The opposite is also possible -- if :option:`size` is set to 20GiB, - and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within - the 0..20GiB region. - -.. option:: filesize=int - - Individual file sizes. May be a range, in which case fio will select sizes - for files at random within the given range and limited to :option:`size` in - total (if that is given). If not given, each created file is the same size. - -.. option:: file_append=bool - - Perform I/O after the end of the file. Normally fio will operate within the - size of a file. If this option is set, then fio will append to the file - instead. This has identical behavior to setting :option:`offset` to the size - of a file. This option is ignored on non-regular files. - -.. option:: fill_device=bool, fill_fs=bool - - Sets size to something really large and waits for ENOSPC (no space left on - device) as the terminating condition. Only makes sense with sequential - write. For a read workload, the mount point will be filled first then I/O - started on the result. This option doesn't make sense if operating on a raw - device node, since the size of that is already known by the file system. - Additionally, writing beyond end-of-device will not return ENOSPC there. - - -I/O engine -~~~~~~~~~~ - -.. option:: ioengine=str - - Defines how the job issues I/O to the file. The following types are defined: - - **sync** - Basic :manpage:`read(2)` or :manpage:`write(2)` - I/O. :manpage:`lseek(2)` is used to position the I/O location. - - **psync** - Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on - all supported operating systems except for Windows. - - **vsync** - Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate - queuing by coalescing adjacent IOs into a single submission. - - **pvsync** - Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O. - - **pvsync2** - Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O. - - **libaio** - Linux native asynchronous I/O. Note that Linux may only support - queued behaviour with non-buffered I/O (set ``direct=1`` or - ``buffered=0``). - This engine defines engine specific options. - - **posixaio** - POSIX asynchronous I/O using :manpage:`aio_read(3)` and - :manpage:`aio_write(3)`. - - **solarisaio** - Solaris native asynchronous I/O. - - **windowsaio** - Windows native asynchronous I/O. Default on Windows. - - **mmap** - File is memory mapped with :manpage:`mmap(2)` and data copied - to/from using :manpage:`memcpy(3)`. - - **splice** - :manpage:`splice(2)` is used to transfer the data and - :manpage:`vmsplice(2)` to transfer data from user space to the - kernel. - - **sg** - SCSI generic sg v3 I/O. May either be synchronous using the SG_IO - ioctl, or if the target is an sg character device we use - :manpage:`read(2)` and :manpage:`write(2)` for asynchronous - I/O. Requires filename option to specify either block or character - devices. - - **null** - Doesn't transfer any data, just pretends to. This is mainly used to - exercise fio itself and for debugging/testing purposes. - - **net** - Transfer over the network to given ``host:port``. Depending on the - :option:`protocol` used, the :option:`hostname`, :option:`port`, - :option:`listen` and :option:`filename` options are used to specify - what sort of connection to make, while the :option:`protocol` option - determines which protocol will be used. This engine defines engine - specific options. - - **netsplice** - Like **net**, but uses :manpage:`splice(2)` and - :manpage:`vmsplice(2)` to map data and send/receive. - This engine defines engine specific options. - - **cpuio** - Doesn't transfer any data, but burns CPU cycles according to the - :option:`cpuload` and :option:`cpuchunks` options. Setting - :option:`cpuload` =85 will cause that job to do nothing but burn 85% - of the CPU. In case of SMP machines, use :option:`numjobs` - = to get desired CPU usage, as the cpuload only loads a - single CPU at the desired rate. A job never finishes unless there is - at least one non-cpuio job. - - **guasi** - The GUASI I/O engine is the Generic Userspace Asyncronous Syscall - Interface approach to async I/O. See - - http://www.xmailserver.org/guasi-lib.html - - for more info on GUASI. - - **rdma** - The RDMA I/O engine supports both RDMA memory semantics - (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the - InfiniBand, RoCE and iWARP protocols. - - **falloc** - I/O engine that does regular fallocate to simulate data transfer as - fio ioengine. - - DDIR_READ - does fallocate(,mode = FALLOC_FL_KEEP_SIZE,). - - DDIR_WRITE - does fallocate(,mode = 0). - - DDIR_TRIM - does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE). - - **e4defrag** - I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate - defragment activity in request to DDIR_WRITE event. - - **rbd** - I/O engine supporting direct access to Ceph Rados Block Devices - (RBD) via librbd without the need to use the kernel rbd driver. This - ioengine defines engine specific options. - - **gfapi** - Using Glusterfs libgfapi sync interface to direct access to - Glusterfs volumes without having to go through FUSE. This ioengine - defines engine specific options. - - **gfapi_async** - Using Glusterfs libgfapi async interface to direct access to - Glusterfs volumes without having to go through FUSE. This ioengine - defines engine specific options. - - **libhdfs** - Read and write through Hadoop (HDFS). The :file:`filename` option - is used to specify host,port of the hdfs name-node to connect. This - engine interprets offsets a little differently. In HDFS, files once - created cannot be modified. So random writes are not possible. To - imitate this, libhdfs engine expects bunch of small files to be - created over HDFS, and engine will randomly pick a file out of those - files based on the offset generated by fio backend. (see the example - job file to create such files, use ``rw=write`` option). Please - note, you might want to set necessary environment variables to work - with hdfs/libhdfs properly. Each jobs uses it's own connection to - HDFS. - - **mtd** - Read, write and erase an MTD character device (e.g., - :file:`/dev/mtd0`). Discards are treated as erases. Depending on the - underlying device type, the I/O may have to go in a certain pattern, - e.g., on NAND, writing sequentially to erase blocks and discarding - before overwriting. The writetrim mode works well for this - constraint. - - **pmemblk** - Read and write using filesystem DAX to a file on a filesystem - mounted with DAX on a persistent memory device through the NVML - libpmemblk library. - - **dev-dax** - Read and write using device DAX to a persistent memory device (e.g., - /dev/dax0.0) through the NVML libpmem library. - - **external** - Prefix to specify loading an external I/O engine object file. Append - the engine filename, eg ``ioengine=external:/tmp/foo.o`` to load - ioengine :file:`foo.o` in :file:`/tmp`. - - -I/O engine specific parameters -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -In addition, there are some parameters which are only valid when a specific -ioengine is in use. These are used identically to normal parameters, with the -caveat that when used on the command line, they must come after the -:option:`ioengine` that defines them is selected. - -.. option:: userspace_reap : [libaio] - - Normally, with the libaio engine in use, fio will use the - :manpage:`io_getevents(2)` system call to reap newly returned events. With - this flag turned on, the AIO ring will be read directly from user-space to - reap events. The reaping mode is only enabled when polling for a minimum of - 0 events (eg when :option:`iodepth_batch_complete` `=0`). - -.. option:: hipri : [psyncv2] - - Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority - than normal. - -.. option:: cpuload=int : [cpuio] - - Attempt to use the specified percentage of CPU cycles. - -.. option:: cpuchunks=int : [cpuio] - - Split the load into cycles of the given time. In microseconds. - -.. option:: exit_on_io_done=bool : [cpuio] - - Detect when I/O threads are done, then exit. - -.. option:: hostname=str : [netsplice] [net] - - The host name or IP address to use for TCP or UDP based I/O. If the job is - a TCP listener or UDP reader, the host name is not used and must be omitted - unless it is a valid UDP multicast address. - -.. option:: namenode=str : [libhdfs] - - The host name or IP address of a HDFS cluster namenode to contact. - -.. option:: port=int - - [netsplice], [net] - - The TCP or UDP port to bind to or connect to. If this is used with - :option:`numjobs` to spawn multiple instances of the same job type, then - this will be the starting port number since fio will use a range of - ports. - - [libhdfs] - - the listening port of the HFDS cluster namenode. - -.. option:: interface=str : [netsplice] [net] - - The IP address of the network interface used to send or receive UDP - multicast. - -.. option:: ttl=int : [netsplice] [net] - - Time-to-live value for outgoing UDP multicast packets. Default: 1. - -.. option:: nodelay=bool : [netsplice] [net] - - Set TCP_NODELAY on TCP connections. - -.. option:: protocol=str : [netsplice] [net] - -.. option:: proto=str : [netsplice] [net] - - The network protocol to use. Accepted values are: - - **tcp** - Transmission control protocol. - **tcpv6** - Transmission control protocol V6. - **udp** - User datagram protocol. - **udpv6** - User datagram protocol V6. - **unix** - UNIX domain socket. - - When the protocol is TCP or UDP, the port must also be given, as well as the - hostname if the job is a TCP listener or UDP reader. For unix sockets, the - normal filename option should be used and the port is invalid. - -.. option:: listen : [net] - - For TCP network connections, tell fio to listen for incoming connections - rather than initiating an outgoing connection. The :option:`hostname` must - be omitted if this option is used. - -.. option:: pingpong : [net] - - Normally a network writer will just continue writing data, and a network - reader will just consume packages. If ``pingpong=1`` is set, a writer will - send its normal payload to the reader, then wait for the reader to send the - same payload back. This allows fio to measure network latencies. The - submission and completion latencies then measure local time spent sending or - receiving, and the completion latency measures how long it took for the - other end to receive and send back. For UDP multicast traffic - ``pingpong=1`` should only be set for a single reader when multiple readers - are listening to the same address. - -.. option:: window_size : [net] - - Set the desired socket buffer size for the connection. - -.. option:: mss : [net] - - Set the TCP maximum segment size (TCP_MAXSEG). - -.. option:: donorname=str : [e4defrag] - - File will be used as a block donor(swap extents between files). - -.. option:: inplace=int : [e4defrag] - - Configure donor file blocks allocation strategy: - - **0** - Default. Preallocate donor's file on init. - **1** - Allocate space immediately inside defragment event, and free right - after event. - -.. option:: clustername=str : [rbd] - - Specifies the name of the Ceph cluster. - -.. option:: rbdname=str : [rbd] - - Specifies the name of the RBD. - -.. option:: pool=str : [rbd] - - Specifies the name of the Ceph pool containing RBD. - -.. option:: clientname=str : [rbd] - - Specifies the username (without the 'client.' prefix) used to access the - Ceph cluster. If the *clustername* is specified, the *clientname* shall be - the full *type.id* string. If no type. prefix is given, fio will add - 'client.' by default. - -.. option:: skip_bad=bool : [mtd] - - Skip operations against known bad blocks. - -.. option:: hdfsdirectory : [libhdfs] - - libhdfs will create chunk in this HDFS directory. - -.. option:: chunk_size : [libhdfs] - - the size of the chunk to use for each file. - - -I/O depth -~~~~~~~~~ - -.. option:: iodepth=int - - Number of I/O units to keep in flight against the file. Note that - increasing *iodepth* beyond 1 will not affect synchronous ioengines (except - for small degress when :option:`verify_async` is in use). Even async - engines may impose OS restrictions causing the desired depth not to be - achieved. This may happen on Linux when using libaio and not setting - :option:`direct` =1, since buffered I/O is not async on that OS. Keep an - eye on the I/O depth distribution in the fio output to verify that the - achieved depth is as expected. Default: 1. - -.. option:: iodepth_batch_submit=int, iodepth_batch=int - - This defines how many pieces of I/O to submit at once. It defaults to 1 - which means that we submit each I/O as soon as it is available, but can be - raised to submit bigger batches of I/O at the time. If it is set to 0 the - :option:`iodepth` value will be used. - -.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int - - This defines how many pieces of I/O to retrieve at once. It defaults to 1 - which means that we'll ask for a minimum of 1 I/O in the retrieval process - from the kernel. The I/O retrieval will go on until we hit the limit set by - :option:`iodepth_low`. If this variable is set to 0, then fio will always - check for completed events before queuing more I/O. This helps reduce I/O - latency, at the cost of more retrieval system calls. - -.. option:: iodepth_batch_complete_max=int - - This defines maximum pieces of I/O to retrieve at once. This variable should - be used along with :option:`iodepth_batch_complete_min` =int variable, - specifying the range of min and max amount of I/O which should be - retrieved. By default it is equal to :option:`iodepth_batch_complete_min` - value. - - Example #1:: - - iodepth_batch_complete_min=1 - iodepth_batch_complete_max= - - which means that we will retrieve at least 1 I/O and up to the whole - submitted queue depth. If none of I/O has been completed yet, we will wait. - - Example #2:: - - iodepth_batch_complete_min=0 - iodepth_batch_complete_max= - - which means that we can retrieve up to the whole submitted queue depth, but - if none of I/O has been completed yet, we will NOT wait and immediately exit - the system call. In this example we simply do polling. - -.. option:: iodepth_low=int - - The low water mark indicating when to start filling the queue - again. Defaults to the same as :option:`iodepth`, meaning that fio will - attempt to keep the queue full at all times. If :option:`iodepth` is set to - eg 16 and *iodepth_low* is set to 4, then after fio has filled the queue of - 16 requests, it will let the depth drain down to 4 before starting to fill - it again. - -.. option:: io_submit_mode=str - - This option controls how fio submits the I/O to the I/O engine. The default - is `inline`, which means that the fio job threads submit and reap I/O - directly. If set to `offload`, the job threads will offload I/O submission - to a dedicated pool of I/O threads. This requires some coordination and thus - has a bit of extra overhead, especially for lower queue depth I/O where it - can increase latencies. The benefit is that fio can manage submission rates - independently of the device completion rates. This avoids skewed latency - reporting if I/O gets back up on the device side (the coordinated omission - problem). - - -I/O rate -~~~~~~~~ - -.. option:: thinktime=int - - Stall the job x microseconds after an I/O has completed before issuing the - next. May be used to simulate processing being done by an application. See - :option:`thinktime_blocks` and :option:`thinktime_spin`. - -.. option:: thinktime_spin=int - - Only valid if :option:`thinktime` is set - pretend to spend CPU time doing - something with the data received, before falling back to sleeping for the - rest of the period specified by :option:`thinktime`. - -.. option:: thinktime_blocks=int - - Only valid if :option:`thinktime` is set - control how many blocks to issue, - before waiting `thinktime` usecs. If not set, defaults to 1 which will make - fio wait `thinktime` usecs after every block. This effectively makes any - queue depth setting redundant, since no more than 1 I/O will be queued - before we have to complete it and do our thinktime. In other words, this - setting effectively caps the queue depth if the latter is larger. - -.. option:: rate=int[,int][,int] - - Cap the bandwidth used by this job. The number is in bytes/sec, the normal - suffix rules apply. Comma-separated values may be specified for reads, - writes, and trims as described in :option:`blocksize`. - -.. option:: rate_min=int[,int][,int] - - Tell fio to do whatever it can to maintain at least this bandwidth. Failing - to meet this requirement will cause the job to exit. Comma-separated values - may be specified for reads, writes, and trims as described in - :option:`blocksize`. - -.. option:: rate_iops=int[,int][,int] - - Cap the bandwidth to this number of IOPS. Basically the same as - :option:`rate`, just specified independently of bandwidth. If the job is - given a block size range instead of a fixed value, the smallest block size - is used as the metric. Comma-separated values may be specified for reads, - writes, and trims as described in :option:`blocksize`. - -.. option:: rate_iops_min=int[,int][,int] - - If fio doesn't meet this rate of I/O, it will cause the job to exit. - Comma-separated values may be specified for reads, writes, and trims as - described in :option:`blocksize`. - -.. option:: rate_process=str - - This option controls how fio manages rated I/O submissions. The default is - `linear`, which submits I/O in a linear fashion with fixed delays between - IOs that gets adjusted based on I/O completion rates. If this is set to - `poisson`, fio will submit I/O based on a more real world random request - flow, known as the Poisson process - (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be - 10^6 / IOPS for the given workload. - - -I/O latency -~~~~~~~~~~~ - -.. option:: latency_target=int - - If set, fio will attempt to find the max performance point that the given - workload will run at while maintaining a latency below this target. The - values is given in microseconds. See :option:`latency_window` and - :option:`latency_percentile`. - -.. option:: latency_window=int - - Used with :option:`latency_target` to specify the sample window that the job - is run at varying queue depths to test the performance. The value is given - in microseconds. - -.. option:: latency_percentile=float - - The percentage of IOs that must fall within the criteria specified by - :option:`latency_target` and :option:`latency_window`. If not set, this - defaults to 100.0, meaning that all IOs must be equal or below to the value - set by :option:`latency_target`. - -.. option:: max_latency=int - - If set, fio will exit the job if it exceeds this maximum latency. It will - exit with an ETIME error. - -.. option:: rate_cycle=int - - Average bandwidth for :option:`rate` and :option:`rate_min` over this number - of milliseconds. - - -I/O replay -~~~~~~~~~~ - -.. option:: write_iolog=str - - Write the issued I/O patterns to the specified file. See - :option:`read_iolog`. Specify a separate file for each job, otherwise the - iologs will be interspersed and the file may be corrupt. - -.. option:: read_iolog=str - - Open an iolog with the specified file name and replay the I/O patterns it - contains. This can be used to store a workload and replay it sometime - later. The iolog given may also be a blktrace binary file, which allows fio - to replay a workload captured by :command:`blktrace`. See - :manpage:`blktrace(8)` for how to capture such logging data. For blktrace - replay, the file needs to be turned into a blkparse binary data file first - (``blkparse -o /dev/null -d file_for_fio.bin``). - -.. option:: replay_no_stall=int - - When replaying I/O with :option:`read_iolog` the default behavior is to - attempt to respect the time stamps within the log and replay them with the - appropriate delay between IOPS. By setting this variable fio will not - respect the timestamps and attempt to replay them as fast as possible while - still respecting ordering. The result is the same I/O pattern to a given - device, but different timings. - -.. option:: replay_redirect=str - - While replaying I/O patterns using :option:`read_iolog` the default behavior - is to replay the IOPS onto the major/minor device that each IOP was recorded - from. This is sometimes undesirable because on a different machine those - major/minor numbers can map to a different device. Changing hardware on the - same system can also result in a different major/minor mapping. - ``replay_redirect`` causes all IOPS to be replayed onto the single specified - device regardless of the device it was recorded - from. i.e. :option:`replay_redirect` = :file:`/dev/sdc` would cause all I/O - in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means - multiple devices will be replayed onto a single device, if the trace - contains multiple devices. If you want multiple devices to be replayed - concurrently to multiple redirected devices you must blkparse your trace - into separate traces and replay them with independent fio invocations. - Unfortunately this also breaks the strict time ordering between multiple - device accesses. - -.. option:: replay_align=int - - Force alignment of I/O offsets and lengths in a trace to this power of 2 - value. - -.. option:: replay_scale=int - - Scale sector offsets down by this factor when replaying traces. - - -Threads, processes and job synchronization -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -.. option:: thread - - Fio defaults to forking jobs, however if this option is given, fio will use - :manpage:`pthread_create(3)` to create threads instead. - -.. option:: wait_for=str - - Specifies the name of the already defined job to wait for. Single waitee - name only may be specified. If set, the job won't be started until all - workers of the waitee job are done. - - ``wait_for`` operates on the job name basis, so there are a few - limitations. First, the waitee must be defined prior to the waiter job - (meaning no forward references). Second, if a job is being referenced as a - waitee, it must have a unique name (no duplicate waitees). - -.. option:: nice=int - - Run the job with the given nice value. See man :manpage:`nice(2)`. - - On Windows, values less than -15 set the process class to "High"; -1 through - -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle" - priority class. - -.. option:: prio=int - - Set the I/O priority value of this job. Linux limits us to a positive value - between 0 and 7, with 0 being the highest. See man - :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating - systems since meaning of priority may differ. - -.. option:: prioclass=int - - Set the I/O priority class. See man :manpage:`ionice(1)`. - -.. option:: cpumask=int - - Set the CPU affinity of this job. The parameter given is a bitmask of - allowed CPU's the job may run on. So if you want the allowed CPUs to be 1 - and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man - :manpage:`sched_setaffinity(2)`. This may not work on all supported - operating systems or kernel versions. This option doesn't work well for a - higher CPU count than what you can store in an integer mask, so it can only - control cpus 1-32. For boxes with larger CPU counts, use - :option:`cpus_allowed`. - -.. option:: cpus_allowed=str - - Controls the same options as :option:`cpumask`, but it allows a text setting - of the permitted CPUs instead. So to use CPUs 1 and 5, you would specify - ``cpus_allowed=1,5``. This options also allows a range of CPUs. Say you - wanted a binding to CPUs 1, 5, and 8-15, you would set - ``cpus_allowed=1,5,8-15``. - -.. option:: cpus_allowed_policy=str - - Set the policy of how fio distributes the CPUs specified by - :option:`cpus_allowed` or cpumask. Two policies are supported: - - **shared** - All jobs will share the CPU set specified. - **split** - Each job will get a unique CPU from the CPU set. - - **shared** is the default behaviour, if the option isn't specified. If - **split** is specified, then fio will will assign one cpu per job. If not - enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs - in the set. - -.. option:: numa_cpu_nodes=str - - Set this job running on specified NUMA nodes' CPUs. The arguments allow - comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable - numa options support, fio must be built on a system with libnuma-dev(el) - installed. - -.. option:: numa_mem_policy=str - - Set this job's memory policy and corresponding NUMA nodes. Format of the - arguments:: - - [:] - - ``mode`` is one of the following memory policy: ``default``, ``prefer``, - ``bind``, ``interleave``, ``local`` For ``default`` and ``local`` memory - policy, no node is needed to be specified. For ``prefer``, only one node is - allowed. For ``bind`` and ``interleave``, it allow comma delimited list of - numbers, A-B ranges, or `all`. - -.. option:: cgroup=str - - Add job to this control group. If it doesn't exist, it will be created. The - system must have a mounted cgroup blkio mount point for this to work. If - your system doesn't have it mounted, you can do so with:: - - # mount -t cgroup -o blkio none /cgroup - -.. option:: cgroup_weight=int - - Set the weight of the cgroup to this value. See the documentation that comes - with the kernel, allowed values are in the range of 100..1000. - -.. option:: cgroup_nodelete=bool - - Normally fio will delete the cgroups it has created after the job - completion. To override this behavior and to leave cgroups around after the - job completion, set ``cgroup_nodelete=1``. This can be useful if one wants - to inspect various cgroup files after job completion. Default: false. - -.. option:: flow_id=int - - The ID of the flow. If not specified, it defaults to being a global - flow. See :option:`flow`. - -.. option:: flow=int - - Weight in token-based flow control. If this value is used, then there is a - 'flow counter' which is used to regulate the proportion of activity between - two or more jobs. Fio attempts to keep this flow counter near zero. The - ``flow`` parameter stands for how much should be added or subtracted to the - flow counter on each iteration of the main I/O loop. That is, if one job has - ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8 - ratio in how much one runs vs the other. - -.. option:: flow_watermark=int - - The maximum value that the absolute value of the flow counter is allowed to - reach before the job must wait for a lower value of the counter. - -.. option:: flow_sleep=int - - The period of time, in microseconds, to wait after the flow watermark has - been exceeded before retrying operations. - -.. option:: stonewall, wait_for_previous - - Wait for preceding jobs in the job file to exit, before starting this - one. Can be used to insert serialization points in the job file. A stone - wall also implies starting a new reporting group, see - :option:`group_reporting`. - -.. option:: exitall - - When one job finishes, terminate the rest. The default is to wait for each - job to finish, sometimes that is not the desired action. - -.. option:: exec_prerun=str - - Before running this job, issue the command specified through - :manpage:`system(3)`. Output is redirected in a file called - :file:`jobname.prerun.txt`. - -.. option:: exec_postrun=str - - After the job completes, issue the command specified though - :manpage:`system(3)`. Output is redirected in a file called - :file:`jobname.postrun.txt`. - -.. option:: uid=int - - Instead of running as the invoking user, set the user ID to this value - before the thread/process does any work. - -.. option:: gid=int - - Set group ID, see :option:`uid`. - - -Verification -~~~~~~~~~~~~ - -.. option:: verify_only - - Do not perform specified workload, only verify data still matches previous - invocation of this workload. This option allows one to check data multiple - times at a later date without overwriting it. This option makes sense only - for workloads that write data, and does not support workloads with the - :option:`time_based` option set. - -.. option:: do_verify=bool - - Run the verify phase after a write phase. Only valid if :option:`verify` is - set. Default: true. - -.. option:: verify=str - - If writing to a file, fio can verify the file contents after each iteration - of the job. Each verification method also implies verification of special - header, which is written to the beginning of each block. This header also - includes meta information, like offset of the block, block number, timestamp - when block was written, etc. :option:`verify` can be combined with - :option:`verify_pattern` option. The allowed values are: - - **md5** - Use an md5 sum of the data area and store it in the header of - each block. - - **crc64** - Use an experimental crc64 sum of the data area and store it in the - header of each block. - - **crc32c** - Use a crc32c sum of the data area and store it in the header of each - block. - - **crc32c-intel** - Use hardware assisted crc32c calculation provided on SSE4.2 enabled - processors. Falls back to regular software crc32c, if not supported - by the system. - - **crc32** - Use a crc32 sum of the data area and store it in the header of each - block. - - **crc16** - Use a crc16 sum of the data area and store it in the header of each - block. - - **crc7** - Use a crc7 sum of the data area and store it in the header of each - block. - - **xxhash** - Use xxhash as the checksum function. Generally the fastest software - checksum that fio supports. - - **sha512** - Use sha512 as the checksum function. - - **sha256** - Use sha256 as the checksum function. - - **sha1** - Use optimized sha1 as the checksum function. - - **meta** - This option is deprecated, since now meta information is included in - generic verification header and meta verification happens by - default. For detailed information see the description of the - :option:`verify` setting. This option is kept because of - compatibility's sake with old configurations. Do not use it. - - **pattern** - Verify a strict pattern. Normally fio includes a header with some - basic information and checksumming, but if this option is set, only - the specific pattern set with :option:`verify_pattern` is verified. - - **null** - Only pretend to verify. Useful for testing internals with - :option:`ioengine` `=null`, not for much else. - - This option can be used for repeated burn-in tests of a system to make sure - that the written data is also correctly read back. If the data direction - given is a read or random read, fio will assume that it should verify a - previously written file. If the data direction includes any form of write, - the verify will be of the newly written data. - -.. option:: verifysort=bool - - If true, fio will sort written verify blocks when it deems it faster to read - them back in a sorted manner. This is often the case when overwriting an - existing file, since the blocks are already laid out in the file system. You - can ignore this option unless doing huge amounts of really fast I/O where - the red-black tree sorting CPU time becomes significant. Default: true. - -.. option:: verifysort_nr=int - - Pre-load and sort verify blocks for a read workload. - -.. option:: verify_offset=int - - Swap the verification header with data somewhere else in the block before - writing. It is swapped back before verifying. - -.. option:: verify_interval=int - - Write the verification header at a finer granularity than the - :option:`blocksize`. It will be written for chunks the size of - ``verify_interval``. :option:`blocksize` should divide this evenly. - -.. option:: verify_pattern=str - - If set, fio will fill the I/O buffers with this pattern. Fio defaults to - filling with totally random bytes, but sometimes it's interesting to fill - with a known pattern for I/O verification purposes. Depending on the width - of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time(it can - be either a decimal or a hex number). The ``verify_pattern`` if larger than - a 32-bit quantity has to be a hex number that starts with either "0x" or - "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o - format, which means that for each block offset will be written and then - verified back, e.g.:: - - verify_pattern=%o - - Or use combination of everything:: - - verify_pattern=0xff%o"abcd"-12 - -.. option:: verify_fatal=bool - - Normally fio will keep checking the entire contents before quitting on a - block verification failure. If this option is set, fio will exit the job on - the first observed failure. Default: false. - -.. option:: verify_dump=bool - - If set, dump the contents of both the original data block and the data block - we read off disk to files. This allows later analysis to inspect just what - kind of data corruption occurred. Off by default. - -.. option:: verify_async=int - - Fio will normally verify I/O inline from the submitting thread. This option - takes an integer describing how many async offload threads to create for I/O - verification instead, causing fio to offload the duty of verifying I/O - contents to one or more separate threads. If using this offload option, even - sync I/O engines can benefit from using an :option:`iodepth` setting higher - than 1, as it allows them to have I/O in flight while verifies are running. - -.. option:: verify_async_cpus=str - - Tell fio to set the given CPU affinity on the async I/O verification - threads. See :option:`cpus_allowed` for the format used. - -.. option:: verify_backlog=int - - Fio will normally verify the written contents of a job that utilizes verify - once that job has completed. In other words, everything is written then - everything is read back and verified. You may want to verify continually - instead for a variety of reasons. Fio stores the meta data associated with - an I/O block in memory, so for large verify workloads, quite a bit of memory - would be used up holding this meta data. If this option is enabled, fio will - write only N blocks before verifying these blocks. - -.. option:: verify_backlog_batch=int - - Control how many blocks fio will verify if :option:`verify_backlog` is - set. If not set, will default to the value of :option:`verify_backlog` - (meaning the entire queue is read back and verified). If - ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all - blocks will be verified, if ``verify_backlog_batch`` is larger than - :option:`verify_backlog`, some blocks will be verified more than once. - -.. option:: verify_state_save=bool - - When a job exits during the write phase of a verify workload, save its - current state. This allows fio to replay up until that point, if the verify - state is loaded for the verify read phase. The format of the filename is, - roughly:: - - ---verify.state. - - is "local" for a local run, "sock" for a client/server socket - connection, and "ip" (192.168.0.1, for instance) for a networked - client/server connection. - -.. option:: verify_state_load=bool - - If a verify termination trigger was used, fio stores the current write state - of each thread. This can be used at verification time so that fio knows how - far it should verify. Without this information, fio will run a full - verification pass, according to the settings in the job file used. - -.. option:: trim_percentage=int - - Number of verify blocks to discard/trim. - -.. option:: trim_verify_zero=bool - - Verify that trim/discarded blocks are returned as zeroes. - -.. option:: trim_backlog=int - - Verify that trim/discarded blocks are returned as zeroes. - -.. option:: trim_backlog_batch=int - - Trim this number of I/O blocks. - -.. option:: experimental_verify=bool - - Enable experimental verification. - - -Steady state -~~~~~~~~~~~~ - -.. option:: steadystate=str:float, ss=str:float - - Define the criterion and limit for assessing steady state performance. The - first parameter designates the criterion whereas the second parameter sets - the threshold. When the criterion falls below the threshold for the - specified duration, the job will stop. For example, `iops_slope:0.1%` will - direct fio to terminate the job when the least squares regression slope - falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled - this will apply to all jobs in the group. Below is the list of available - steady state assessment criteria. All assessments are carried out using only - data from the rolling collection window. Threshold limits can be expressed - as a fixed value or as a percentage of the mean in the collection window. - - **iops** - Collect IOPS data. Stop the job if all individual IOPS measurements - are within the specified limit of the mean IOPS (e.g., ``iops:2`` - means that all individual IOPS values must be within 2 of the mean, - whereas ``iops:0.2%`` means that all individual IOPS values must be - within 0.2% of the mean IOPS to terminate the job). - - **iops_slope** - Collect IOPS data and calculate the least squares regression - slope. Stop the job if the slope falls below the specified limit. - - **bw** - Collect bandwidth data. Stop the job if all individual bandwidth - measurements are within the specified limit of the mean bandwidth. - - **bw_slope** - Collect bandwidth data and calculate the least squares regression - slope. Stop the job if the slope falls below the specified limit. - -.. option:: steadystate_duration=time, ss_dur=time - - A rolling window of this duration will be used to judge whether steady state - has been reached. Data will be collected once per second. The default is 0 - which disables steady state detection. - -.. option:: steadystate_ramp_time=time, ss_ramp=time - - Allow the job to run for the specified duration before beginning data - collection for checking the steady state job termination criterion. The - default is 0. - - -Measurements and reporting -~~~~~~~~~~~~~~~~~~~~~~~~~~ - -.. option:: per_job_logs=bool - - If set, this generates bw/clat/iops log with per file private filenames. If - not set, jobs with identical names will share the log filename. Default: - true. - -.. option:: group_reporting - - It may sometimes be interesting to display statistics for groups of jobs as - a whole instead of for each individual job. This is especially true if - :option:`numjobs` is used; looking at individual thread/process output - quickly becomes unwieldy. To see the final report per-group instead of - per-job, use :option:`group_reporting`. Jobs in a file will be part of the - same reporting group, unless if separated by a :option:`stonewall`, or by - using :option:`new_group`. - -.. option:: new_group - - Start a new reporting group. See: :option:`group_reporting`. If not given, - all jobs in a file will be part of the same reporting group, unless - separated by a :option:`stonewall`. - -.. option:: write_bw_log=str - - If given, write a bandwidth log for this job. Can be used to store data of - the bandwidth of the jobs in their lifetime. The included - :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these - text files into nice graphs. See :option:`write_lat_log` for behaviour of - given filename. For this option, the postfix is :file:`_bw.x.log`, where `x` - is the index of the job (`1..N`, where `N` is the number of jobs). If - :option:`per_job_logs` is false, then the filename will not include the job - index. See `Log File Formats`_. - -.. option:: write_lat_log=str - - Same as :option:`write_bw_log`, except that this option stores I/O - submission, completion, and total latencies instead. If no filename is given - with this option, the default filename of :file:`jobname_type.log` is - used. Even if the filename is given, fio will still append the type of - log. So if one specifies:: - - write_lat_log=foo - - The actual log names will be :file:`foo_slat.x.log`, :file:`foo_clat.x.log`, - and :file:`foo_lat.x.log`, where `x` is the index of the job (1..N, where N - is the number of jobs). This helps :command:`fio_generate_plot` find the - logs automatically. If :option:`per_job_logs` is false, then the filename - will not include the job index. See `Log File Formats`_. - -.. option:: write_hist_log=str - - Same as :option:`write_lat_log`, but writes I/O completion latency - histograms. If no filename is given with this option, the default filename - of :file:`jobname_clat_hist.x.log` is used, where `x` is the index of the - job (1..N, where `N` is the number of jobs). Even if the filename is given, - fio will still append the type of log. If :option:`per_job_logs` is false, - then the filename will not include the job index. See `Log File Formats`_. - -.. option:: write_iops_log=str - - Same as :option:`write_bw_log`, but writes IOPS. If no filename is given - with this option, the default filename of :file:`jobname_type.x.log` is - used,where `x` is the index of the job (1..N, where `N` is the number of - jobs). Even if the filename is given, fio will still append the type of - log. If :option:`per_job_logs` is false, then the filename will not include - the job index. See `Log File Formats`_. - -.. option:: log_avg_msec=int - - By default, fio will log an entry in the iops, latency, or bw log for every - I/O that completes. When writing to the disk log, that can quickly grow to a - very large size. Setting this option makes fio average the each log entry - over the specified period of time, reducing the resolution of the log. See - :option:`log_max_value` as well. Defaults to 0, logging all entries. - -.. option:: log_hist_msec=int - - Same as :option:`log_avg_msec`, but logs entries for completion latency - histograms. Computing latency percentiles from averages of intervals using - :option:`log_avg_msec` is innacurate. Setting this option makes fio log - histogram entries over the specified period of time, reducing log sizes for - high IOPS devices while retaining percentile accuracy. See - :option:`log_hist_coarseness` as well. Defaults to 0, meaning histogram - logging is disabled. - -.. option:: log_hist_coarseness=int - - Integer ranging from 0 to 6, defining the coarseness of the resolution of - the histogram logs enabled with :option:`log_hist_msec`. For each increment - in coarseness, fio outputs half as many bins. Defaults to 0, for which - histogram logs contain 1216 latency bins. See `Log File Formats`_. - -.. option:: log_max_value=bool - - If :option:`log_avg_msec` is set, fio logs the average over that window. If - you instead want to log the maximum value, set this option to 1. Defaults to - 0, meaning that averaged values are logged. - -.. option:: log_offset=int - - If this is set, the iolog options will include the byte offset for the I/O - entry as well as the other data values. - -.. option:: log_compression=int - - If this is set, fio will compress the I/O logs as it goes, to keep the - memory footprint lower. When a log reaches the specified size, that chunk is - removed and compressed in the background. Given that I/O logs are fairly - highly compressible, this yields a nice memory savings for longer runs. The - downside is that the compression will consume some background CPU cycles, so - it may impact the run. This, however, is also true if the logging ends up - consuming most of the system memory. So pick your poison. The I/O logs are - saved normally at the end of a run, by decompressing the chunks and storing - them in the specified log file. This feature depends on the availability of - zlib. - -.. option:: log_compression_cpus=str - - Define the set of CPUs that are allowed to handle online log compression for - the I/O jobs. This can provide better isolation between performance - sensitive jobs, and background compression work. - -.. option:: log_store_compressed=bool - - If set, fio will store the log files in a compressed format. They can be - decompressed with fio, using the :option:`--inflate-log` command line - parameter. The files will be stored with a :file:`.fz` suffix. - -.. option:: log_unix_epoch=bool - - If set, fio will log Unix timestamps to the log files produced by enabling - write_type_log for each log type, instead of the default zero-based - timestamps. - -.. option:: block_error_percentiles=bool - - If set, record errors in trim block-sized units from writes and trims and - output a histogram of how many trims it took to get to errors, and what kind - of error was encountered. - -.. option:: bwavgtime=int - - Average the calculated bandwidth over the given time. Value is specified in - milliseconds. If the job also does bandwidth logging through - :option:`write_bw_log`, then the minimum of this option and - :option:`log_avg_msec` will be used. Default: 500ms. - -.. option:: iopsavgtime=int - - Average the calculated IOPS over the given time. Value is specified in - milliseconds. If the job also does IOPS logging through - :option:`write_iops_log`, then the minimum of this option and - :option:`log_avg_msec` will be used. Default: 500ms. - -.. option:: disk_util=bool - - Generate disk utilization statistics, if the platform supports it. - Default: true. - -.. option:: disable_lat=bool - - Disable measurements of total latency numbers. Useful only for cutting back - the number of calls to :manpage:`gettimeofday(2)`, as that does impact - performance at really high IOPS rates. Note that to really get rid of a - large amount of these calls, this option must be used with - :option:`disable_slat` and :option:`disable_bw` as well. - -.. option:: disable_clat=bool - - Disable measurements of completion latency numbers. See - :option:`disable_lat`. - -.. option:: disable_slat=bool - - Disable measurements of submission latency numbers. See - :option:`disable_slat`. - -.. option:: disable_bw=bool - - Disable measurements of throughput/bandwidth numbers. See - :option:`disable_lat`. - -.. option:: clat_percentiles=bool - - Enable the reporting of percentiles of completion latencies. - -.. option:: percentile_list=float_list - - Overwrite the default list of percentiles for completion latencies and the - block error histogram. Each number is a floating number in the range - (0,100], and the maximum length of the list is 20. Use ``:`` to separate the - numbers, and list the numbers in ascending order. For example, - ``--percentile_list=99.5:99.9`` will cause fio to report the values of - completion latency below which 99.5% and 99.9% of the observed latencies - fell, respectively. - - -Error handling -~~~~~~~~~~~~~~ - -.. option:: exitall_on_error - - When one job finishes in error, terminate the rest. The default is to wait - for each job to finish. - -.. option:: continue_on_error=str - - Normally fio will exit the job on the first observed failure. If this option - is set, fio will continue the job when there is a 'non-fatal error' (EIO or - EILSEQ) until the runtime is exceeded or the I/O size specified is - completed. If this option is used, there are two more stats that are - appended, the total error count and the first error. The error field given - in the stats is the first error that was hit during the run. - - The allowed values are: - - **none** - Exit on any I/O or verify errors. - - **read** - Continue on read errors, exit on all others. - - **write** - Continue on write errors, exit on all others. - - **io** - Continue on any I/O error, exit on all others. - - **verify** - Continue on verify errors, exit on all others. - - **all** - Continue on all errors. - - **0** - Backward-compatible alias for 'none'. - - **1** - Backward-compatible alias for 'all'. - -.. option:: ignore_error=str - - Sometimes you want to ignore some errors during test in that case you can - specify error list for each error type. - ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for - given error type is separated with ':'. Error may be symbol ('ENOSPC', - 'ENOMEM') or integer. Example:: - - ignore_error=EAGAIN,ENOSPC:122 - - This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from - WRITE. - -.. option:: error_dump=bool - - If set dump every error even if it is non fatal, true by default. If - disabled only fatal error will be dumped. - - -Interpreting the output ------------------------ - -Fio spits out a lot of output. While running, fio will display the status of the -jobs created. An example of that would be:: - - Jobs: 1: [_r] [24.8% done] [r=20992KiB/s,w=24064KiB/s,t=0KiB/s] [r=82,w=94,t=0 iops] [eta 00h:01m:31s] - -The characters inside the square brackets denote the current status of each -thread. The possible values (in typical life cycle order) are: - -+------+-----+-----------------------------------------------------------+ -| Idle | Run | | -+======+=====+===========================================================+ -| P | | Thread setup, but not started. | -+------+-----+-----------------------------------------------------------+ -| C | | Thread created. | -+------+-----+-----------------------------------------------------------+ -| I | | Thread initialized, waiting or generating necessary data. | -+------+-----+-----------------------------------------------------------+ -| | p | Thread running pre-reading file(s). | -+------+-----+-----------------------------------------------------------+ -| | R | Running, doing sequential reads. | -+------+-----+-----------------------------------------------------------+ -| | r | Running, doing random reads. | -+------+-----+-----------------------------------------------------------+ -| | W | Running, doing sequential writes. | -+------+-----+-----------------------------------------------------------+ -| | w | Running, doing random writes. | -+------+-----+-----------------------------------------------------------+ -| | M | Running, doing mixed sequential reads/writes. | -+------+-----+-----------------------------------------------------------+ -| | m | Running, doing mixed random reads/writes. | -+------+-----+-----------------------------------------------------------+ -| | F | Running, currently waiting for :manpage:`fsync(2)` | -+------+-----+-----------------------------------------------------------+ -| | V | Running, doing verification of written data. | -+------+-----+-----------------------------------------------------------+ -| E | | Thread exited, not reaped by main thread yet. | -+------+-----+-----------------------------------------------------------+ -| _ | | Thread reaped, or | -+------+-----+-----------------------------------------------------------+ -| X | | Thread reaped, exited with an error. | -+------+-----+-----------------------------------------------------------+ -| K | | Thread reaped, exited due to signal. | -+------+-----+-----------------------------------------------------------+ - -Fio will condense the thread string as not to take up more space on the command -line as is needed. For instance, if you have 10 readers and 10 writers running, -the output would look like this:: - - Jobs: 20 (f=20): [R(10),W(10)] [4.0% done] [r=20992KiB/s,w=24064KiB/s,t=0KiB/s] [r=82,w=94,t=0 iops] [eta 57m:36s] - -Fio will still maintain the ordering, though. So the above means that jobs 1..10 -are readers, and 11..20 are writers. - -The other values are fairly self explanatory -- number of threads currently -running and doing I/O, rate of I/O since last check (read speed listed first, -then write speed), and the estimated completion percentage and time for the -running group. It's impossible to estimate runtime of the following groups (if -any). Note that the string is displayed in order, so it's possible to tell which -of the jobs are currently doing what. The first character is the first job -defined in the job file, and so forth. - -When fio is done (or interrupted by :kbd:`ctrl-c`), it will show the data for -each thread, group of threads, and disks in that order. For each data direction, -the output looks like:: - - Client1 (g=0): err= 0: - write: io= 32MiB, bw= 666KiB/s, iops=89 , runt= 50320msec - slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92 - clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82 - bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68 - cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17 - IO depths : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0% - submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% - complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% - issued r/w: total=0/32768, short=0/0 - lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%, - lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0% - -The client number is printed, along with the group id and error of that -thread. Below is the I/O statistics, here for writes. In the order listed, they -denote: - -**io** - Number of megabytes I/O performed. - -**bw** - Average bandwidth rate. - -**iops** - Average IOs performed per second. - -**runt** - The runtime of that thread. - -**slat** - Submission latency (avg being the average, stdev being the standard - deviation). This is the time it took to submit the I/O. For sync I/O, - the slat is really the completion latency, since queue/complete is one - operation there. This value can be in milliseconds or microseconds, fio - will choose the most appropriate base and print that. In the example - above, milliseconds is the best scale. Note: in :option:`--minimal` mode - latencies are always expressed in microseconds. - -**clat** - Completion latency. Same names as slat, this denotes the time from - submission to completion of the I/O pieces. For sync I/O, clat will - usually be equal (or very close) to 0, as the time from submit to - complete is basically just CPU time (I/O has already been done, see slat - explanation). - -**bw** - Bandwidth. Same names as the xlat stats, but also includes an - approximate percentage of total aggregate bandwidth this thread received - in this group. This last value is only really useful if the threads in - this group are on the same disk, since they are then competing for disk - access. - -**cpu** - CPU usage. User and system time, along with the number of context - switches this thread went through, usage of system and user time, and - finally the number of major and minor page faults. The CPU utilization - numbers are averages for the jobs in that reporting group, while the - context and fault counters are summed. - -**IO depths** - The distribution of I/O depths over the job life time. The numbers are - divided into powers of 2, so for example the 16= entries includes depths - up to that value but higher than the previous entry. In other words, it - covers the range from 16 to 31. - -**IO submit** - How many pieces of I/O were submitting in a single submit call. Each - entry denotes that amount and below, until the previous entry -- eg, - 8=100% mean that we submitted anywhere in between 5-8 IOs per submit - call. - -**IO complete** - Like the above submit number, but for completions instead. - -**IO issued** - The number of read/write requests issued, and how many of them were - short. - -**IO latencies** - The distribution of I/O completion latencies. This is the time from when - I/O leaves fio and when it gets completed. The numbers follow the same - pattern as the I/O depths, meaning that 2=1.6% means that 1.6% of the - I/O completed within 2 msecs, 20=12.8% means that 12.8% of the I/O took - more than 10 msecs, but less than (or equal to) 20 msecs. - -After each client has been listed, the group statistics are printed. They -will look like this:: - - Run status group 0 (all jobs): - READ: io=64MB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec - WRITE: io=64MB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec - -For each data direction, it prints: - -**io** - Number of megabytes I/O performed. -**aggrb** - Aggregate bandwidth of threads in this group. -**minb** - The minimum average bandwidth a thread saw. -**maxb** - The maximum average bandwidth a thread saw. -**mint** - The smallest runtime of the threads in that group. -**maxt** - The longest runtime of the threads in that group. - -And finally, the disk statistics are printed. They will look like this:: - - Disk stats (read/write): - sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% - -Each value is printed for both reads and writes, with reads first. The -numbers denote: - -**ios** - Number of ios performed by all groups. -**merge** - Number of merges I/O the I/O scheduler. -**ticks** - Number of ticks we kept the disk busy. -**io_queue** - Total time spent in the disk queue. -**util** - The disk utilization. A value of 100% means we kept the disk - busy constantly, 50% would be a disk idling half of the time. - -It is also possible to get fio to dump the current output while it is running, -without terminating the job. To do that, send fio the **USR1** signal. You can -also get regularly timed dumps by using the :option:`--status-interval` -parameter, or by creating a file in :file:`/tmp` named -:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the -current output status. - - -Terse output ------------- - -For scripted usage where you typically want to generate tables or graphs of the -results, fio can output the results in a semicolon separated format. The format -is one long line of values, such as:: - - 2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00% - A description of this job goes here. - -The job description (if provided) follows on a second line. - -To enable terse output, use the :option:`--minimal` command line option. The -first value is the version of the terse output format. If the output has to be -changed for some reason, this number will be incremented by 1 to signify that -change. - -Split up, the format is as follows: - - :: - - terse version, fio version, jobname, groupid, error - - READ status:: - - Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec) - Submission latency: min, max, mean, stdev (usec) - Completion latency: min, max, mean, stdev (usec) - Completion latency percentiles: 20 fields (see below) - Total latency: min, max, mean, stdev (usec) - Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev - - WRITE status: - - :: - - Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec) - Submission latency: min, max, mean, stdev (usec) - Completion latency: min, max, mean, stdev(usec) - Completion latency percentiles: 20 fields (see below) - Total latency: min, max, mean, stdev (usec) - Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev - - CPU usage:: - - user, system, context switches, major faults, minor faults - - I/O depths:: - - <=1, 2, 4, 8, 16, 32, >=64 - - I/O latencies microseconds:: - - <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000 - - I/O latencies milliseconds:: - - <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000 - - Disk utilization:: - - Disk name, Read ios, write ios, - Read merges, write merges, - Read ticks, write ticks, - Time spent in queue, disk utilization percentage - - Additional Info (dependent on continue_on_error, default off):: - - total # errors, first error code - - Additional Info (dependent on description being set):: - - Text description - -Completion latency percentiles can be a grouping of up to 20 sets, so for the -terse output fio writes all of them. Each field will look like this:: - - 1.00%=6112 - -which is the Xth percentile, and the `usec` latency associated with it. - -For disk utilization, all disks used by fio are shown. So for each disk there -will be a disk utilization section. - - -Trace file format ------------------ - -There are two trace file format that you can encounter. The older (v1) format is -unsupported since version 1.20-rc3 (March 2008). It will still be described -below in case that you get an old trace and want to understand it. - -In any case the trace is a simple text file with a single action per line. - - -Trace file format v1 -~~~~~~~~~~~~~~~~~~~~ - -Each line represents a single I/O action in the following format:: - - rw, offset, length - -where `rw=0/1` for read/write, and the offset and length entries being in bytes. - -This format is not supported in fio versions => 1.20-rc3. - - -Trace file format v2 -~~~~~~~~~~~~~~~~~~~~ - -The second version of the trace file format was added in fio version 1.17. It -allows to access more then one file per trace and has a bigger set of possible -file actions. - -The first line of the trace file has to be:: - - fio version 2 iolog - -Following this can be lines in two different formats, which are described below. - -The file management format:: - - filename action - -The filename is given as an absolute path. The action can be one of these: - -**add** - Add the given filename to the trace. -**open** - Open the file with the given filename. The filename has to have - been added with the **add** action before. -**close** - Close the file with the given filename. The file has to have been - opened before. - - -The file I/O action format:: - - filename action offset length - -The `filename` is given as an absolute path, and has to have been added and -opened before it can be used with this format. The `offset` and `length` are -given in bytes. The `action` can be one of these: - -**wait** - Wait for `offset` microseconds. Everything below 100 is discarded. - The time is relative to the previous `wait` statement. -**read** - Read `length` bytes beginning from `offset`. -**write** - Write `length` bytes beginning from `offset`. -**sync** - :manpage:`fsync(2)` the file. -**datasync** - :manpage:`fdatasync(2)` the file. -**trim** - Trim the given file from the given `offset` for `length` bytes. - -CPU idleness profiling ----------------------- - -In some cases, we want to understand CPU overhead in a test. For example, we -test patches for the specific goodness of whether they reduce CPU usage. -Fio implements a balloon approach to create a thread per CPU that runs at idle -priority, meaning that it only runs when nobody else needs the cpu. -By measuring the amount of work completed by the thread, idleness of each CPU -can be derived accordingly. - -An unit work is defined as touching a full page of unsigned characters. Mean and -standard deviation of time to complete an unit work is reported in "unit work" -section. Options can be chosen to report detailed percpu idleness or overall -system idleness by aggregating percpu stats. - - -Verification and triggers -------------------------- - -Fio is usually run in one of two ways, when data verification is done. The first -is a normal write job of some sort with verify enabled. When the write phase has -completed, fio switches to reads and verifies everything it wrote. The second -model is running just the write phase, and then later on running the same job -(but with reads instead of writes) to repeat the same I/O patterns and verify -the contents. Both of these methods depend on the write phase being completed, -as fio otherwise has no idea how much data was written. - -With verification triggers, fio supports dumping the current write state to -local files. Then a subsequent read verify workload can load this state and know -exactly where to stop. This is useful for testing cases where power is cut to a -server in a managed fashion, for instance. - -A verification trigger consists of two things: - -1) Storing the write state of each job. -2) Executing a trigger command. - -The write state is relatively small, on the order of hundreds of bytes to single -kilobytes. It contains information on the number of completions done, the last X -completions, etc. - -A trigger is invoked either through creation ('touch') of a specified file in -the system, or through a timeout setting. If fio is run with -:option:`--trigger-file` = :file:`/tmp/trigger-file`, then it will continually -check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it -will fire off the trigger (thus saving state, and executing the trigger -command). - -For client/server runs, there's both a local and remote trigger. If fio is -running as a server backend, it will send the job states back to the client for -safe storage, then execute the remote trigger, if specified. If a local trigger -is specified, the server will still send back the write state, but the client -will then execute the trigger. - -Verification trigger example -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Lets say we want to run a powercut test on the remote machine 'server'. Our -write workload is in :file:`write-test.fio`. We want to cut power to 'server' at -some point during the run, and we'll run this test from the safety or our local -machine, 'localbox'. On the server, we'll start the fio backend normally:: - - server# fio --server - -and on the client, we'll fire off the workload:: - - localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\"" - -We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute:: - - echo b > /proc/sysrq-trigger - -on the server once it has received the trigger and sent us the write state. This -will work, but it's not **really** cutting power to the server, it's merely -abruptly rebooting it. If we have a remote way of cutting power to the server -through IPMI or similar, we could do that through a local trigger command -instead. Lets assume we have a script that does IPMI reboot of a given hostname, -ipmi-reboot. On localbox, we could then have run fio with a local trigger -instead:: - - localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server" - -For this case, fio would wait for the server to send us the write state, then -execute ``ipmi-reboot server`` when that happened. - -Loading verify state -~~~~~~~~~~~~~~~~~~~~ - -To load store write state, read verification job file must contain the -:option:`verify_state_load` option. If that is set, fio will load the previously -stored state. For a local fio run this is done by loading the files directly, -and on a client/server run, the server backend will ask the client to send the -files over and load them from there. - - -Log File Formats ----------------- - -Fio supports a variety of log file formats, for logging latencies, bandwidth, -and IOPS. The logs share a common format, which looks like this: - - *time* (`msec`), *value*, *data direction*, *offset* - -Time for the log entry is always in milliseconds. The *value* logged depends -on the type of log, it will be one of the following: - - **Latency log** - Value is latency in usecs - **Bandwidth log** - Value is in KiB/sec - **IOPS log** - Value is IOPS - -*Data direction* is one of the following: - - **0** - I/O is a READ - **1** - I/O is a WRITE - **2** - I/O is a TRIM - -The *offset* is the offset, in bytes, from the start of the file, for that -particular I/O. The logging of the offset can be toggled with -:option:`log_offset`. - -If windowed logging is enabled through :option:`log_avg_msec` then fio doesn't -log individual IOs. Instead of logs the average values over the specified period -of time. Since 'data direction' and 'offset' are per-I/O values, they aren't -applicable if windowed logging is enabled. If windowed logging is enabled and -:option:`log_max_value` is set, then fio logs maximum values in that window -instead of averages. - - -Client/server -------------- - -Normally fio is invoked as a stand-alone application on the machine where the -I/O workload should be generated. However, the frontend and backend of fio can -be run separately. Ie the fio server can generate an I/O workload on the "Device -Under Test" while being controlled from another machine. - -Start the server on the machine which has access to the storage DUT:: - - fio --server=args - -where args defines what fio listens to. The arguments are of the form -``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP -v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket. -*hostname* is either a hostname or IP address, and *port* is the port to listen -to (only valid for TCP/IP, not a local socket). Some examples: - -1) ``fio --server`` - - Start a fio server, listening on all interfaces on the default port (8765). - -2) ``fio --server=ip:hostname,4444`` - - Start a fio server, listening on IP belonging to hostname and on port 4444. - -3) ``fio --server=ip6:::1,4444`` - - Start a fio server, listening on IPv6 localhost ::1 and on port 4444. - -4) ``fio --server=,4444`` - - Start a fio server, listening on all interfaces on port 4444. - -5) ``fio --server=1.2.3.4`` - - Start a fio server, listening on IP 1.2.3.4 on the default port. - -6) ``fio --server=sock:/tmp/fio.sock`` - - Start a fio server, listening on the local socket /tmp/fio.sock. - -Once a server is running, a "client" can connect to the fio server with:: - - fio --client= - -where `local-args` are arguments for the client where it is running, `server` -is the connect string, and `remote-args` and `job file(s)` are sent to the -server. The `server` string follows the same format as it does on the server -side, to allow IP/hostname/socket and port strings. - -Fio can connect to multiple servers this way:: - - fio --client= --client= - -If the job file is located on the fio server, then you can tell the server to -load a local file as well. This is done by using :option:`--remote-config` :: - - fio --client=server --remote-config /path/to/file.fio - -Then fio will open this local (to the server) job file instead of being passed -one from the client. - -If you have many servers (example: 100 VMs/containers), you can input a pathname -of a file containing host IPs/names as the parameter value for the -:option:`--client` option. For example, here is an example :file:`host.list` -file containing 2 hostnames:: - - host1.your.dns.domain - host2.your.dns.domain - -The fio command would then be:: - - fio --client=host.list - -In this mode, you cannot input server-specific parameters or job files -- all -servers receive the same job file. - -In order to let ``fio --client`` runs use a shared filesystem from multiple -hosts, ``fio --client`` now prepends the IP address of the server to the -filename. For example, if fio is using directory :file:`/mnt/nfs/fio` and is -writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile` -containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and -192.168.10.121, then fio will create two files:: - - /mnt/nfs/fio/192.168.10.120.fileio.tmp - /mnt/nfs/fio/192.168.10.121.fileio.tmp diff --git a/README b/README new file mode 100644 index 00000000..8f5385ef --- /dev/null +++ b/README @@ -0,0 +1,268 @@ +Overview and history +-------------------- + +Fio was originally written to save me the hassle of writing special test case +programs when I wanted to test a specific workload, either for performance +reasons or to find/reproduce a bug. The process of writing such a test app can +be tiresome, especially if you have to do it often. Hence I needed a tool that +would be able to simulate a given I/O workload without resorting to writing a +tailored test case again and again. + +A test work load is difficult to define, though. There can be any number of +processes or threads involved, and they can each be using their own way of +generating I/O. You could have someone dirtying large amounts of memory in an +memory mapped file, or maybe several threads issuing reads using asynchronous +I/O. fio needed to be flexible enough to simulate both of these cases, and many +more. + +Fio spawns a number of threads or processes doing a particular type of I/O +action as specified by the user. fio takes a number of global parameters, each +inherited by the thread unless otherwise parameters given to them overriding +that setting is given. The typical use of fio is to write a job file matching +the I/O load one wants to simulate. + + +Source +------ + +Fio resides in a git repo, the canonical place is: + + git://git.kernel.dk/fio.git + +When inside a corporate firewall, git:// URL sometimes does not work. +If git:// does not work, use the http protocol instead: + + http://git.kernel.dk/fio.git + +Snapshots are frequently generated and :file:`fio-git-*.tar.gz` include the git +meta data as well. Other tarballs are archives of official fio releases. +Snapshots can download from: + + http://brick.kernel.dk/snaps/ + +There are also two official mirrors. Both of these are automatically synced with +the main repository, when changes are pushed. If the main repo is down for some +reason, either one of these is safe to use as a backup: + + git://git.kernel.org/pub/scm/linux/kernel/git/axboe/fio.git + + https://git.kernel.org/pub/scm/linux/kernel/git/axboe/fio.git + +or + + git://github.com/axboe/fio.git + + https://github.com/axboe/fio.git + + +Mailing list +------------ + +The fio project mailing list is meant for anything related to fio including +general discussion, bug reporting, questions, and development. + +An automated mail detailing recent commits is automatically sent to the list at +most daily. The list address is fio@vger.kernel.org, subscribe by sending an +email to majordomo@vger.kernel.org with + + subscribe fio + +in the body of the email. Archives can be found here: + + http://www.spinics.net/lists/fio/ + +and archives for the old list can be found here: + + http://maillist.kernel.dk/fio-devel/ + + +Author +------ + +Fio was written by Jens Axboe to enable flexible testing of +the Linux I/O subsystem and schedulers. He got tired of writing specific test +applications to simulate a given workload, and found that the existing I/O +benchmark/test tools out there weren't flexible enough to do what he wanted. + +Jens Axboe 20060905 + + +Binary packages +--------------- + +Debian: + Starting with Debian "Squeeze", fio packages are part of the official + Debian repository. http://packages.debian.org/search?keywords=fio. + +Ubuntu: + Starting with Ubuntu 10.04 LTS (aka "Lucid Lynx"), fio packages are part + of the Ubuntu "universe" repository. + http://packages.ubuntu.com/search?keywords=fio. + +Red Hat, CentOS & Co: + Dag Wieërs has RPMs for Red Hat related distros, find them here: + http://dag.wieers.com/rpm/packages/fio/. + +Mandriva: + Mandriva has integrated fio into their package repository, so installing + on that distro should be as easy as typing ``urpmi fio``. + +Solaris: + Packages for Solaris are available from OpenCSW. Install their pkgutil + tool (http://www.opencsw.org/get-it/pkgutil/) and then install fio via + ``pkgutil -i fio``. + +Windows: + Rebecca Cran has fio packages for Windows at + http://www.bluestop.org/fio/ . + +BSDs: + Packages for BSDs may be available from their binary package repositories. + Look for a package "fio" using their binary package managers. + + +Building +-------- + +Just type:: + + $ ./configure + $ make + $ make install + +Note that GNU make is required. On BSDs it's available from devel/gmake within +ports directory; on Solaris it's in the SUNWgmake package. On platforms where +GNU make isn't the default, type ``gmake`` instead of ``make``. + +Configure will print the enabled options. Note that on Linux based platforms, +the libaio development packages must be installed to use the libaio +engine. Depending on distro, it is usually called libaio-devel or libaio-dev. + +For gfio, gtk 2.18 (or newer), associated glib threads, and cairo are required +to be installed. gfio isn't built automatically and can be enabled with a +``--enable-gfio`` option to configure. + +To build fio with a cross-compiler:: + + $ make clean + $ make CROSS_COMPILE=/path/to/toolchain/prefix + +Configure will attempt to determine the target platform automatically. + +It's possible to build fio for ESX as well, use the ``--esx`` switch to +configure. + + +Windows +~~~~~~~ + +On Windows, Cygwin (http://www.cygwin.com/) is required in order to build +fio. To create an MSI installer package install WiX 3.8 from +http://wixtoolset.org and run :file:`dobuild.cmd` from the :file:`os/windows` +directory. + +How to compile fio on 64-bit Windows: + + 1. Install Cygwin (http://www.cygwin.com/). Install **make** and all + packages starting with **mingw64-i686** and **mingw64-x86_64**. + 2. Open the Cygwin Terminal. + 3. Go to the fio directory (source files). + 4. Run ``make clean && make -j``. + +To build fio on 32-bit Windows, run ``./configure --build-32bit-win`` before +``make``. + +It's recommended that once built or installed, fio be run in a Command Prompt or +other 'native' console such as console2, since there are known to be display and +signal issues when running it under a Cygwin shell (see +http://code.google.com/p/mintty/issues/detail?id=56 for details). + + +Documentation +~~~~~~~~~~~~~ + +Fio uses Sphinx_ to generate documentation from the reStructuredText_ files. +To build HTML formatted documentation run ``make -C doc html`` and direct your +browser to :file:`./doc/output/html/index.html`. To build manual page run +``make -C doc man`` and then ``man doc/output/man/fio.1``. To see what other +output formats are supported run ``make -C doc help``. + +.. _reStructuredText: http://www.sphinx-doc.org/rest.html +.. _Sphinx: http://www.sphinx-doc.org + + +Platforms +--------- + +Fio works on (at least) Linux, Solaris, AIX, HP-UX, OSX, NetBSD, OpenBSD, +Windows, FreeBSD, and DragonFly. Some features and/or options may only be +available on some of the platforms, typically because those features only apply +to that platform (like the solarisaio engine, or the splice engine on Linux). + +Some features are not available on FreeBSD/Solaris even if they could be +implemented, I'd be happy to take patches for that. An example of that is disk +utility statistics and (I think) huge page support, support for that does exist +in FreeBSD/Solaris. + +Fio uses pthread mutexes for signalling and locking and FreeBSD does not +support process shared pthread mutexes. As a result, only threads are +supported on FreeBSD. This could be fixed with sysv ipc locking or +other locking alternatives. + +Other \*BSD platforms are untested, but fio should work there almost out of the +box. Since I don't do test runs or even compiles on those platforms, your +mileage may vary. Sending me patches for other platforms is greatly +appreciated. There's a lot of value in having the same test/benchmark tool +available on all platforms. + +Note that POSIX aio is not enabled by default on AIX. Messages like these:: + + Symbol resolution failed for /usr/lib/libc.a(posix_aio.o) because: + Symbol _posix_kaio_rdwr (number 2) is not exported from dependent module /unix. + +indicate one needs to enable POSIX aio. Run the following commands as root:: + + # lsdev -C -l posix_aio0 + posix_aio0 Defined Posix Asynchronous I/O + # cfgmgr -l posix_aio0 + # lsdev -C -l posix_aio0 + posix_aio0 Available Posix Asynchronous I/O + +POSIX aio should work now. To make the change permanent:: + + # chdev -l posix_aio0 -P -a autoconfig='available' + posix_aio0 changed + + +Running fio +----------- + +Running fio is normally the easiest part - you just give it the job file +(or job files) as parameters:: + + $ fio [options] [jobfile] ... + +and it will start doing what the *jobfile* tells it to do. You can give more +than one job file on the command line, fio will serialize the running of those +files. Internally that is the same as using the :option:`stonewall` parameter +described in the parameter section. + +If the job file contains only one job, you may as well just give the parameters +on the command line. The command line parameters are identical to the job +parameters, with a few extra that control global parameters. For example, for +the job file parameter :option:`iodepth=2 `, the mirror command line +option would be :option:`--iodepth 2 ` or :option:`--iodepth=2 +`. You can also use the command line for giving more than one job +entry. For each :option:`--name ` option that fio sees, it will start a +new job with that name. Command line entries following a +:option:`--name ` entry will apply to that job, until there are no more +entries or a new :option:`--name ` entry is seen. This is similar to the +job file options, where each option applies to the current job until a new [] +job entry is seen. + +fio does not need to run as root, except if the files or devices specified in +the job section requires that. Some other options may also be restricted, such +as memory locking, I/O scheduler switching, and decreasing the nice value. + +If *jobfile* is specified as ``-``, the job file will be read from standard +input. diff --git a/README.rst b/README.rst deleted file mode 100644 index 8f5385ef..00000000 --- a/README.rst +++ /dev/null @@ -1,268 +0,0 @@ -Overview and history --------------------- - -Fio was originally written to save me the hassle of writing special test case -programs when I wanted to test a specific workload, either for performance -reasons or to find/reproduce a bug. The process of writing such a test app can -be tiresome, especially if you have to do it often. Hence I needed a tool that -would be able to simulate a given I/O workload without resorting to writing a -tailored test case again and again. - -A test work load is difficult to define, though. There can be any number of -processes or threads involved, and they can each be using their own way of -generating I/O. You could have someone dirtying large amounts of memory in an -memory mapped file, or maybe several threads issuing reads using asynchronous -I/O. fio needed to be flexible enough to simulate both of these cases, and many -more. - -Fio spawns a number of threads or processes doing a particular type of I/O -action as specified by the user. fio takes a number of global parameters, each -inherited by the thread unless otherwise parameters given to them overriding -that setting is given. The typical use of fio is to write a job file matching -the I/O load one wants to simulate. - - -Source ------- - -Fio resides in a git repo, the canonical place is: - - git://git.kernel.dk/fio.git - -When inside a corporate firewall, git:// URL sometimes does not work. -If git:// does not work, use the http protocol instead: - - http://git.kernel.dk/fio.git - -Snapshots are frequently generated and :file:`fio-git-*.tar.gz` include the git -meta data as well. Other tarballs are archives of official fio releases. -Snapshots can download from: - - http://brick.kernel.dk/snaps/ - -There are also two official mirrors. Both of these are automatically synced with -the main repository, when changes are pushed. If the main repo is down for some -reason, either one of these is safe to use as a backup: - - git://git.kernel.org/pub/scm/linux/kernel/git/axboe/fio.git - - https://git.kernel.org/pub/scm/linux/kernel/git/axboe/fio.git - -or - - git://github.com/axboe/fio.git - - https://github.com/axboe/fio.git - - -Mailing list ------------- - -The fio project mailing list is meant for anything related to fio including -general discussion, bug reporting, questions, and development. - -An automated mail detailing recent commits is automatically sent to the list at -most daily. The list address is fio@vger.kernel.org, subscribe by sending an -email to majordomo@vger.kernel.org with - - subscribe fio - -in the body of the email. Archives can be found here: - - http://www.spinics.net/lists/fio/ - -and archives for the old list can be found here: - - http://maillist.kernel.dk/fio-devel/ - - -Author ------- - -Fio was written by Jens Axboe to enable flexible testing of -the Linux I/O subsystem and schedulers. He got tired of writing specific test -applications to simulate a given workload, and found that the existing I/O -benchmark/test tools out there weren't flexible enough to do what he wanted. - -Jens Axboe 20060905 - - -Binary packages ---------------- - -Debian: - Starting with Debian "Squeeze", fio packages are part of the official - Debian repository. http://packages.debian.org/search?keywords=fio. - -Ubuntu: - Starting with Ubuntu 10.04 LTS (aka "Lucid Lynx"), fio packages are part - of the Ubuntu "universe" repository. - http://packages.ubuntu.com/search?keywords=fio. - -Red Hat, CentOS & Co: - Dag Wieërs has RPMs for Red Hat related distros, find them here: - http://dag.wieers.com/rpm/packages/fio/. - -Mandriva: - Mandriva has integrated fio into their package repository, so installing - on that distro should be as easy as typing ``urpmi fio``. - -Solaris: - Packages for Solaris are available from OpenCSW. Install their pkgutil - tool (http://www.opencsw.org/get-it/pkgutil/) and then install fio via - ``pkgutil -i fio``. - -Windows: - Rebecca Cran has fio packages for Windows at - http://www.bluestop.org/fio/ . - -BSDs: - Packages for BSDs may be available from their binary package repositories. - Look for a package "fio" using their binary package managers. - - -Building --------- - -Just type:: - - $ ./configure - $ make - $ make install - -Note that GNU make is required. On BSDs it's available from devel/gmake within -ports directory; on Solaris it's in the SUNWgmake package. On platforms where -GNU make isn't the default, type ``gmake`` instead of ``make``. - -Configure will print the enabled options. Note that on Linux based platforms, -the libaio development packages must be installed to use the libaio -engine. Depending on distro, it is usually called libaio-devel or libaio-dev. - -For gfio, gtk 2.18 (or newer), associated glib threads, and cairo are required -to be installed. gfio isn't built automatically and can be enabled with a -``--enable-gfio`` option to configure. - -To build fio with a cross-compiler:: - - $ make clean - $ make CROSS_COMPILE=/path/to/toolchain/prefix - -Configure will attempt to determine the target platform automatically. - -It's possible to build fio for ESX as well, use the ``--esx`` switch to -configure. - - -Windows -~~~~~~~ - -On Windows, Cygwin (http://www.cygwin.com/) is required in order to build -fio. To create an MSI installer package install WiX 3.8 from -http://wixtoolset.org and run :file:`dobuild.cmd` from the :file:`os/windows` -directory. - -How to compile fio on 64-bit Windows: - - 1. Install Cygwin (http://www.cygwin.com/). Install **make** and all - packages starting with **mingw64-i686** and **mingw64-x86_64**. - 2. Open the Cygwin Terminal. - 3. Go to the fio directory (source files). - 4. Run ``make clean && make -j``. - -To build fio on 32-bit Windows, run ``./configure --build-32bit-win`` before -``make``. - -It's recommended that once built or installed, fio be run in a Command Prompt or -other 'native' console such as console2, since there are known to be display and -signal issues when running it under a Cygwin shell (see -http://code.google.com/p/mintty/issues/detail?id=56 for details). - - -Documentation -~~~~~~~~~~~~~ - -Fio uses Sphinx_ to generate documentation from the reStructuredText_ files. -To build HTML formatted documentation run ``make -C doc html`` and direct your -browser to :file:`./doc/output/html/index.html`. To build manual page run -``make -C doc man`` and then ``man doc/output/man/fio.1``. To see what other -output formats are supported run ``make -C doc help``. - -.. _reStructuredText: http://www.sphinx-doc.org/rest.html -.. _Sphinx: http://www.sphinx-doc.org - - -Platforms ---------- - -Fio works on (at least) Linux, Solaris, AIX, HP-UX, OSX, NetBSD, OpenBSD, -Windows, FreeBSD, and DragonFly. Some features and/or options may only be -available on some of the platforms, typically because those features only apply -to that platform (like the solarisaio engine, or the splice engine on Linux). - -Some features are not available on FreeBSD/Solaris even if they could be -implemented, I'd be happy to take patches for that. An example of that is disk -utility statistics and (I think) huge page support, support for that does exist -in FreeBSD/Solaris. - -Fio uses pthread mutexes for signalling and locking and FreeBSD does not -support process shared pthread mutexes. As a result, only threads are -supported on FreeBSD. This could be fixed with sysv ipc locking or -other locking alternatives. - -Other \*BSD platforms are untested, but fio should work there almost out of the -box. Since I don't do test runs or even compiles on those platforms, your -mileage may vary. Sending me patches for other platforms is greatly -appreciated. There's a lot of value in having the same test/benchmark tool -available on all platforms. - -Note that POSIX aio is not enabled by default on AIX. Messages like these:: - - Symbol resolution failed for /usr/lib/libc.a(posix_aio.o) because: - Symbol _posix_kaio_rdwr (number 2) is not exported from dependent module /unix. - -indicate one needs to enable POSIX aio. Run the following commands as root:: - - # lsdev -C -l posix_aio0 - posix_aio0 Defined Posix Asynchronous I/O - # cfgmgr -l posix_aio0 - # lsdev -C -l posix_aio0 - posix_aio0 Available Posix Asynchronous I/O - -POSIX aio should work now. To make the change permanent:: - - # chdev -l posix_aio0 -P -a autoconfig='available' - posix_aio0 changed - - -Running fio ------------ - -Running fio is normally the easiest part - you just give it the job file -(or job files) as parameters:: - - $ fio [options] [jobfile] ... - -and it will start doing what the *jobfile* tells it to do. You can give more -than one job file on the command line, fio will serialize the running of those -files. Internally that is the same as using the :option:`stonewall` parameter -described in the parameter section. - -If the job file contains only one job, you may as well just give the parameters -on the command line. The command line parameters are identical to the job -parameters, with a few extra that control global parameters. For example, for -the job file parameter :option:`iodepth=2 `, the mirror command line -option would be :option:`--iodepth 2 ` or :option:`--iodepth=2 -`. You can also use the command line for giving more than one job -entry. For each :option:`--name ` option that fio sees, it will start a -new job with that name. Command line entries following a -:option:`--name ` entry will apply to that job, until there are no more -entries or a new :option:`--name ` entry is seen. This is similar to the -job file options, where each option applies to the current job until a new [] -job entry is seen. - -fio does not need to run as root, except if the files or devices specified in -the job section requires that. Some other options may also be restricted, such -as memory locking, I/O scheduler switching, and decreasing the nice value. - -If *jobfile* is specified as ``-``, the job file will be read from standard -input. diff --git a/doc/fio_doc.rst b/doc/fio_doc.rst index 34e7fde9..b5987b52 100644 --- a/doc/fio_doc.rst +++ b/doc/fio_doc.rst @@ -2,10 +2,10 @@ fio - Flexible I/O tester rev. |version| ======================================== -.. include:: ../README.rst +.. include:: ../README -.. include:: ../HOWTO.rst +.. include:: ../HOWTO diff --git a/doc/fio_man.rst b/doc/fio_man.rst index 765a01ca..7eae05e2 100644 --- a/doc/fio_man.rst +++ b/doc/fio_man.rst @@ -5,7 +5,7 @@ (rev. |release|) -.. include:: ../README.rst +.. include:: ../README -.. include:: ../HOWTO.rst +.. include:: ../HOWTO