X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=731684cb9d62c7766155ba050ee66178ea19c428;hp=66ebebe8579dd5954e574bf016c31b5fbd0e5baf;hb=be4ecfdf6c8daa75c4df8ac875c9a87da80d81a0;hpb=47d85e2bd4763204a983c7bf4833c0d466dc36ca diff --git a/HOWTO b/HOWTO index 66ebebe8..731684cb 100644 --- a/HOWTO +++ b/HOWTO @@ -111,7 +111,7 @@ several global sections if so desired. A job is only affected by a global section residing above it. If the first character in a line is a ';' or a '#', the entire line is discarded as a comment. -So lets look at a really simple job file that define to threads, each +So let's look at a really simple job file that defines two processes, each randomly reading from a 128MiB file. ; -- start job file -- @@ -133,7 +133,7 @@ line, this job would look as follows: $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2 -Lets look at an example that have a number of processes writing randomly +Let's look at an example that has a number of processes writing randomly to files. ; -- start job file -- @@ -158,6 +158,33 @@ specify: $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4 +fio also supports environment variable expansion in job files. Any +substring 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 + +; -- 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: + +; -- 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. @@ -171,18 +198,21 @@ a string. The following types are used: str String. This is a sequence of alpha characters. int Integer. A whole number value, can be negative. If prefixed with - 0x, the integer is assumed to be of base 16 (hexidecimal). + 0x, the integer is assumed to be of base 16 (hexadecimal). +time Integer with possible time postfix. In seconds unless otherwise + specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds, + minutes, and hours. siint SI integer. A whole number value, which may contain a postfix describing the base of the number. Accepted postfixes are k/m/g, meaning kilo, mega, and giga. So if you want to specify 4096, you could either write out '4096' or just give 4k. The postfixes signify base 2 values, so 1024 is 1k and 1024k is 1m and so on. If the option accepts an upper and lower range, use a colon ':' - or minus '-' to seperate such values. See irange. + or minus '-' to separate such values. See irange. bool Boolean. Usually parsed as an integer, however only defined for true and false (1 and 0). irange Integer range with postfix. Allows value range to be given, such - as 1024-4096. A colon may also be used as the seperator, eg + 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 siint. @@ -210,7 +240,7 @@ filename=str Fio normally makes up a filename based on the job name, the ioengine used is 'net', the filename is the host and port to connect to in the format of =host/port. If the ioengine is file based, you can specify a number of files - by seperating the names with a ':' colon. So if you wanted + by separating the names with a ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb as the two working files, you would use filename=/dev/sda:/dev/sdb. '-' is a reserved name, meaning stdin or stdout. Which of the two depends @@ -235,7 +265,7 @@ lockfile=str Fio defaults to not doing any locking files before it does The option may be post-fixed with a lock batch number. If set, then each thread/process may do that amount of IOs to - the file before giving up the lock. Since lock acqusition is + the file before giving up the lock. Since lock acquisition is expensive, batching the lock/unlocks will speed up IO. readwrite=str @@ -336,6 +366,12 @@ bs_unaligned If this option is given, any byte size value within bsrange zero_buffers If this option is given, fio will init the IO buffers to all zeroes. The default is to fill them with random data. +refill_buffers If this option is given, fio will refill the IO 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. + nrfiles=int Number of files to use for this job. Defaults to 1. openfiles=int Number of files to keep open at the same time. Defaults to @@ -369,6 +405,8 @@ ioengine=str Defines how the job issues io to the file. The following posixaio glibc posix asynchronous io. + solarisaio Solaris native asynchronous io. + mmap File is memory mapped and data copied to/from using memcpy(3). @@ -425,11 +463,21 @@ iodepth=int This defines how many io units to keep in flight against job, can be overridden with a larger value for higher concurrency. +iodepth_batch_submit=int iodepth_batch=int This defines how many pieces of IO to submit at once. It defaults to 1 which means that we submit each IO as soon as it is available, but can be raised to submit bigger batches of IO at the time. +iodepth_batch_complete=int This defines how many pieces of IO to retrieve + at once. It defaults to 1 which means that we'll ask + for a minimum of 1 IO in the retrieval process from + the kernel. The IO retrieval will go on until we + hit the limit set by iodepth_low. If this variable is + set to 0, then fio will always check for completed + events before queuing more IO. This helps reduce + IO latency, at the cost of more retrieval system calls. + iodepth_low=int The low water mark indicating when to start filling the queue again. Defaults to the same as iodepth, meaning that fio will attempt to keep the queue full at all times. @@ -454,7 +502,11 @@ fsync=int If writing to a file, issue a sync of the dirty data not sync the file. The exception is the sg io engine, which synchronizes the disk cache anyway. -overwrite=bool If writing to a file, setup the file first and do overwrites. +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. end_fsync=bool If true, fsync file contents when the job exits. @@ -462,10 +514,6 @@ fsync_on_close=bool If true, fio will fsync() 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. -rwmixcycle=int Value in milliseconds describing how often to switch between - reads and writes for a mixed workload. The default is - 500 msecs. - rwmixread=int How large a percentage of the mix should be reads. rwmixwrite=int How large a percentage of the mix should be writes. If both @@ -535,27 +583,40 @@ cpumask=int Set the CPU affinity of this job. The parameter given is a the allowed CPUs to be 1 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man sched_setaffinity(2). This may not work on all supported - operating systems or kernel versions. + 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 cpus_allowed. cpus_allowed=str Controls the same options as 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. + 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. -startdelay=int Start this job the specified number of seconds after fio +startdelay=time Start this job the specified number of seconds after fio has started. Only useful if the job file contains several jobs, and you want to delay starting some jobs to a certain time. -runtime=int Tell fio to terminate processing after the specified number +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. time_based If set, fio will run for the duration of the runtime - specified even if the file(s) are completey read or + specified even if the file(s) are completely read or written. It will simply loop over the same workload as many times as the runtime allows. +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 runtime is specified. + invalidate=bool Invalidate the buffer/page cache parts for this file prior to starting io. Defaults to true. @@ -623,8 +684,8 @@ create_fsync=bool fsync the data file after creation. This is the default. unlink=bool Unlink the job files when done. Not the default, as repeated - runs of that job would then waste time recreating the fileset - again and again. + runs of that job would then waste time recreating the file + set again and again. loops=int Run the specified number of iterations of this job. Used to repeat the same workload a given number of times. Defaults @@ -643,6 +704,12 @@ verify=str If writing to a file, fio can verify the file contents 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 calcuation + provided on SSE4.2 enabled processors. + crc32 Use a crc32 sum of the data area and store it in the header of each block. @@ -705,7 +772,7 @@ stonewall Wait for preceeding jobs in the job file to exit, before new_group Start a new reporting group. If this option isn't given, jobs in a file will be part of the same reporting group - unless seperated by a stone wall (or if it's a group + unless separated by a stone wall (or if it's a group by itself, with the numjobs option). numjobs=int Create the specified number of clones of this job. May be @@ -742,14 +809,23 @@ read_iolog=str Open an iolog with the specified file name and replay the the file needs to be turned into a blkparse binary data file first (blktrace -d file_for_fio.bin). -write_bw_log If given, write a bandwidth log of the jobs in this job +write_bw_log=str If given, write a bandwidth log of the jobs in this job file. Can be used to store data of the bandwidth of the jobs in their lifetime. The included fio_generate_plots script uses gnuplot to turn these text files into nice - graphs. + graphs. See write_log_log for behaviour of given + filename. For this option, the postfix is _bw.log. + +write_lat_log=str Same as write_bw_log, except that this option stores io + completion latencies instead. If no filename is given + with this option, the default filename of "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 Same as write_bw_log, except that this option stores io - completion latencies instead. + write_lat_log=foo + + The actual log names will be foo_clat.log and foo_slat.log. + This helps fio_generate_plot fine the logs automatically. lockmem=siint Pin down the specified amount of memory with mlock(2). Can potentially be used instead of removing memory or booting @@ -773,6 +849,38 @@ cpuchunks=int If the job is a CPU cycle eater, split the load into disk_util=bool Generate disk utilization statistics, if the platform supports it. Defaults to on. +disable_clat=bool Disable measurements of completion latency numbers. Useful + only for cutting back the number of calls to gettimeofday, + 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 disable_slat and + disable_bw as well. + +disable_slat=bool Disable measurements of submission latency numbers. See + disable_clat. + +disable_bw=bool Disable measurements of throughput/bandwidth numbers. See + disable_clat. + +gtod_reduce=bool Enable all of the gettimeofday() reducing options + (disable_clat, disable_slat, disable_bw) plus reduce + precision of the timeout somewhat to really shrink + the gettimeofday() call count. With this option enabled, + we only do about 0.4% of the gtod() calls we would have + done if all time keeping was enabled. + +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 gettimeofday() + 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 IO + workloads need only copy that segment, instead of entering + the kernel with a gettimeofday() 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. + 6.0 Interpreting the output --------------------------- @@ -818,6 +926,8 @@ Client1 (g=0): err= 0: 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% @@ -833,9 +943,9 @@ runt= The runtime of that thread standard deviation). This is the time it took to submit the io. For sync io, the slat is really the completion latency, since queue/complete is one operation there. This - value can be in miliseconds or microseconds, fio will choose + value can be in milliseconds or microseconds, fio will choose the most appropriate base and print that. In the example - above, miliseconds is the best scale. + above, milliseconds is the best scale. clat= Completion latency. Same names as slat, this denotes the time from submission to completion of the io pieces. For sync io, clat will usually be equal (or very close) to 0, @@ -855,6 +965,11 @@ IO depths= The distribution of io depths over the job life time. 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 IO 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 IO completion latencies. This is the @@ -906,6 +1021,8 @@ The format is one long line of values, such as: client1;0;0;1906777;1090804;1790;0;0;0.000000;0.000000;0;0;0.000000;0.000000;929380;1152890;25.510151%;1078276.333333;128948.113404;0;0;0;0;0;0.000000;0.000000;0;0;0.000000;0.000000;0;0;0.000000%;0.000000;0.000000;100.000000%;0.000000%;324;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%;0.0%;100.0%;0.0%;0.0%;0.0%;0.0%;0.0% ;0.0%;0.0%;0.0%;0.0%;0.0% +To enable terse output, use the --minimal command line option. + Split up, the format is as follows: jobname, groupid, error