X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=3d6b354b87b7df40f723c497ab82b1424cd287f6;hp=0b438714c56cba93b9f319178231b258bb2ee47e;hb=1d2af02a16fc3c3561c994be4de887b926b2b774;hpb=0a839f308177e95c4c45c41ee1d4fa2b8f231f24 diff --git a/HOWTO b/HOWTO index 0b438714..3d6b354b 100644 --- a/HOWTO +++ b/HOWTO @@ -170,7 +170,8 @@ Some parameters take an option of a given type, such as an integer or a string. The following types are used: str String. This is a sequence of alpha characters. -int Integer. A whole number value, may be negative. +int Integer. A whole number value, can be negative. If prefixed with + 0x, the integer is assumed to be of base 16 (hexidecimal). 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, @@ -249,18 +250,22 @@ fadvise_hint=bool By default, fio will use fadvise() to advise the kernel If set, fio will use POSIX_FADV_SEQUENTIAL for sequential IO and POSIX_FADV_RANDOM for random IO. -size=siint The total size of file io for this job. This may describe - the size of the single file the job uses, or it may be - divided between the number of files in the job. If the - file already exists, the file size will be adjusted to this - size if larger than the current file size. If this parameter - is not given and the file exists, the file size will be used. +size=siint The total size of file io for this job. Fio will run until + this many bytes has been transferred, unless runtime is + limited by other options (such as 'runtime', for instance). + Unless specific nr_files and filesize options are given, + fio will divide this size between the available files + specified by the job. filesize=siint 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 'size' in total (if that is given). If not given, each created file is the same size. +fill_device=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. + blocksize=siint bs=siint The block size used for the io units. Defaults to 4k. Values can be given for both read and writes. If a single siint is @@ -280,6 +285,30 @@ bsrange=irange Instead of giving a single block size, specify a range writes, however a second range can be given after a comma. See bs=. +bssplit=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. + blocksize_unaligned bs_unaligned If this option is given, any byte size value within bsrange may be used as a block range. This typically wont work with @@ -313,6 +342,10 @@ ioengine=str Defines how the job issues io to the file. The following sync Basic read(2) or write(2) io. lseek(2) is used to position the io location. + psync Basic pread(2) or pwrite(2) io. + + vsync Basic readv(2) or writev(3) IO. + libaio Linux native asynchronous io. posixaio glibc posix asynchronous io. @@ -343,7 +376,10 @@ ioengine=str Defines how the job issues io to the file. The following or receive, if the latter only the port argument is used. - cpu Doesn't transfer any data, but burns CPU + netsplice Like net, but uses splice/vmsplice to + map data and send/receive. + + cpuio Doesn't transfer any data, but burns CPU cycles according to the cpuload= and cpucycle= options. Setting cpuload=85 will cause that job to do nothing but burn @@ -368,8 +404,9 @@ iodepth=int This defines how many io units to keep in flight against concurrency. iodepth_batch=int This defines how many pieces of IO to submit at once. - It defaults to the same as iodepth, but can be set lower - if one so desires. + 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_low=int The low water mark indicating when to start filling the queue again. Defaults to the same as iodepth, meaning @@ -419,7 +456,9 @@ norandommap Normally fio will cover every block of the file when doing new random offset without looking at past io history. This means that some blocks may not be read or written, and that some blocks may be read/written more than once. This option - is mutually exclusive with verify= for that reason. + is mutually exclusive with verify= for that reason, since + fio doesn't track potential block rewrites which may alter + the calculated checksum for that block. nice=int Run the job with the given nice value. See man nice(2). @@ -464,8 +503,15 @@ ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number of milliseconds. cpumask=int Set the CPU affinity of this job. The parameter given is a - bitmask of allowed CPU's the job may run on. See man - sched_setaffinity(2). + 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 + sched_setaffinity(2). This may not work on all supported + operating systems or kernel versions. + +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. startdelay=int Start this job the specified number of seconds after fio has started. Only useful if the job file contains several @@ -556,15 +602,36 @@ 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. +do_verify=bool Run the verify phase after a write phase. Only makes sense if + verify is set. Defaults to 1. + verify=str If writing to a file, fio can verify the file contents after each iteration of the job. 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. + 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. + + sha512 Use sha512 as the checksum function. + + sha256 Use sha256 as the checksum function. + + meta Write extra information about each io + (timestamp, block number etc.). The block + number is verified. + null Only pretend to verify. Useful for testing internals with ioengine=null, not for much else. @@ -580,6 +647,28 @@ verifysort=bool If set, fio will sort written verify blocks when it deems can ignore this option unless doing huge amounts of really fast IO where the red-black tree sorting CPU time becomes significant. + +verify_offset=siint Swap the verification header with data somewhere else + in the block before writing. Its swapped back before + verifying. + +verify_interval=siint Write the verification header at a finer granularity + than the blocksize. It will be written for chunks the + size of header_interval. blocksize should divide this + evenly. + +verify_pattern=int If set, fio will fill the io buffers with this + pattern. Fio defaults to filling with totally random + bytes, but sometimes it's interesting to fill with a known + pattern for io verification purposes. Depending on the + width of the pattern, fio will fill 1/2/3/4 bytes of the + buffer at the time. The verify_pattern cannot be larger than + a 32-bit quantity. + +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. stonewall Wait for preceeding jobs in the job file to exit, before starting this one. Can be used to insert serialization @@ -618,7 +707,12 @@ write_iolog=str Write the issued io patterns to the specified file. See read_iolog=str Open an iolog with the specified file name and replay the io patterns it contains. This can be used to store a - workload and replay it sometime later. + 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 blktrace. See blktrace + for how to capture such logging data. For blktrace replay, + 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 file. Can be used to store data of the bandwidth of the @@ -680,9 +774,10 @@ E Thread exited, not reaped by main thread yet. _ Thread reaped. The other values are fairly self explanatory - number of threads -currently running and doing io, rate of io since last check, and the estimated -completion percentage and time for the running group. It's impossible to -estimate runtime of the following groups (if any). +currently running and doing io, rate of io 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). When fio is done (or interrupted by ctrl-c), it will show the data for each thread, group of threads, and disks in that order. For each data @@ -693,7 +788,7 @@ Client1 (g=0): err= 0: 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 + 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% 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%, @@ -709,7 +804,10 @@ 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 io. For sync io, the slat is really the completion - latency, since queue/complete is one operation there. + latency, since queue/complete is one operation there. This + value can be in miliseconds or microseconds, fio will choose + the most appropriate base and print that. In the example + above, miliseconds 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, @@ -721,7 +819,9 @@ runt= The runtime of that thread 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. + of context switches this thread went through, usage of + system and user time, and finally the number of major + and minor page faults. IO depths= The distribution of io 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 @@ -791,7 +891,7 @@ Split up, the format is as follows: Submission latency: min, max, mean, deviation Completion latency: min, max, mean, deviation Bw: min, max, aggregate percentage of total, mean, deviation - CPU usage: user, system, context switches + CPU usage: user, system, context switches, major faults, minor faults IO depths: <=1, 2, 4, 8, 16, 32, >=64 IO latencies: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000 Text description