configure: add gettid() test
[fio.git] / HOWTO
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1How fio works
2-------------
3
4The first step in getting fio to simulate a desired I/O workload, is writing a
5job file describing that specific setup. A job file may contain any number of
6threads and/or files -- the typical contents of the job file is a *global*
7section defining shared parameters, and one or more job sections describing the
8jobs involved. When run, fio parses this file and sets everything up as
9described. If we break down a job from top to bottom, it contains the following
10basic parameters:
11
12`I/O type`_
13
14 Defines the I/O pattern issued to the file(s). We may only be reading
15 sequentially from this file(s), or we may be writing randomly. Or even
16 mixing reads and writes, sequentially or randomly.
17 Should we be doing buffered I/O, or direct/raw I/O?
18
19`Block size`_
20
21 In how large chunks are we issuing I/O? This may be a single value,
22 or it may describe a range of block sizes.
23
24`I/O size`_
25
26 How much data are we going to be reading/writing.
27
28`I/O engine`_
29
30 How do we issue I/O? We could be memory mapping the file, we could be
31 using regular read/write, we could be using splice, async I/O, or even
32 SG (SCSI generic sg).
33
34`I/O depth`_
35
36 If the I/O engine is async, how large a queuing depth do we want to
37 maintain?
38
39
40`Target file/device`_
41
42 How many files are we spreading the workload over.
43
44`Threads, processes and job synchronization`_
45
46 How many threads or processes should we spread this workload over.
47
48The above are the basic parameters defined for a workload, in addition there's a
49multitude of parameters that modify other aspects of how this job behaves.
50
51
52Command line options
53--------------------
54
55.. option:: --debug=type
56
f50fbdda 57 Enable verbose tracing `type` of various fio actions. May be ``all`` for all types
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58 or individual types separated by a comma (e.g. ``--debug=file,mem`` will
59 enable file and memory debugging). Currently, additional logging is
60 available for:
f80dba8d 61
b034c0dd 62 *process*
f80dba8d 63 Dump info related to processes.
b034c0dd 64 *file*
f80dba8d 65 Dump info related to file actions.
b034c0dd 66 *io*
f80dba8d 67 Dump info related to I/O queuing.
b034c0dd 68 *mem*
f80dba8d 69 Dump info related to memory allocations.
b034c0dd 70 *blktrace*
f80dba8d 71 Dump info related to blktrace setup.
b034c0dd 72 *verify*
f80dba8d 73 Dump info related to I/O verification.
b034c0dd 74 *all*
f80dba8d 75 Enable all debug options.
b034c0dd 76 *random*
f80dba8d 77 Dump info related to random offset generation.
b034c0dd 78 *parse*
f80dba8d 79 Dump info related to option matching and parsing.
b034c0dd 80 *diskutil*
f80dba8d 81 Dump info related to disk utilization updates.
b034c0dd 82 *job:x*
f80dba8d 83 Dump info only related to job number x.
b034c0dd 84 *mutex*
f80dba8d 85 Dump info only related to mutex up/down ops.
b034c0dd 86 *profile*
f80dba8d 87 Dump info related to profile extensions.
b034c0dd 88 *time*
f80dba8d 89 Dump info related to internal time keeping.
b034c0dd 90 *net*
f80dba8d 91 Dump info related to networking connections.
b034c0dd 92 *rate*
f80dba8d 93 Dump info related to I/O rate switching.
b034c0dd 94 *compress*
f80dba8d 95 Dump info related to log compress/decompress.
b034c0dd 96 *?* or *help*
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97 Show available debug options.
98
99.. option:: --parse-only
100
25cd4b95 101 Parse options only, don't start any I/O.
f80dba8d 102
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103.. option:: --merge-blktrace-only
104
105 Merge blktraces only, don't start any I/O.
106
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107.. option:: --output=filename
108
109 Write output to file `filename`.
110
f50fbdda 111.. option:: --output-format=format
b8f7e412 112
f50fbdda 113 Set the reporting `format` to `normal`, `terse`, `json`, or `json+`. Multiple
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114 formats can be selected, separated by a comma. `terse` is a CSV based
115 format. `json+` is like `json`, except it adds a full dump of the latency
116 buckets.
117
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118.. option:: --bandwidth-log
119
120 Generate aggregate bandwidth logs.
121
122.. option:: --minimal
123
124 Print statistics in a terse, semicolon-delimited format.
125
126.. option:: --append-terse
127
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128 Print statistics in selected mode AND terse, semicolon-delimited format.
129 **Deprecated**, use :option:`--output-format` instead to select multiple
130 formats.
f80dba8d 131
f50fbdda 132.. option:: --terse-version=version
f80dba8d 133
f50fbdda 134 Set terse `version` output format (default 3, or 2 or 4 or 5).
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135
136.. option:: --version
137
b8f7e412 138 Print version information and exit.
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139
140.. option:: --help
141
113f0e7c 142 Print a summary of the command line options and exit.
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143
144.. option:: --cpuclock-test
145
146 Perform test and validation of internal CPU clock.
147
113f0e7c 148.. option:: --crctest=[test]
f80dba8d 149
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150 Test the speed of the built-in checksumming functions. If no argument is
151 given, all of them are tested. Alternatively, a comma separated list can
152 be passed, in which case the given ones are tested.
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153
154.. option:: --cmdhelp=command
155
156 Print help information for `command`. May be ``all`` for all commands.
157
158.. option:: --enghelp=[ioengine[,command]]
159
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160 List all commands defined by `ioengine`, or print help for `command`
161 defined by `ioengine`. If no `ioengine` is given, list all
b034c0dd 162 available ioengines.
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163
164.. option:: --showcmd=jobfile
165
b8f7e412 166 Convert `jobfile` to a set of command-line options.
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167
168.. option:: --readonly
169
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170 Turn on safety read-only checks, preventing writes and trims. The
171 ``--readonly`` option is an extra safety guard to prevent users from
172 accidentally starting a write or trim workload when that is not desired.
173 Fio will only modify the device under test if
174 `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite` is given. This
175 safety net can be used as an extra precaution.
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176
177.. option:: --eta=when
178
b8f7e412 179 Specifies when real-time ETA estimate should be printed. `when` may be
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180 `always`, `never` or `auto`. `auto` is the default, it prints ETA
181 when requested if the output is a TTY. `always` disregards the output
182 type, and prints ETA when requested. `never` never prints ETA.
183
184.. option:: --eta-interval=time
185
186 By default, fio requests client ETA status roughly every second. With
187 this option, the interval is configurable. Fio imposes a minimum
188 allowed time to avoid flooding the console, less than 250 msec is
189 not supported.
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190
191.. option:: --eta-newline=time
192
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193 Force a new line for every `time` period passed. When the unit is omitted,
194 the value is interpreted in seconds.
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195
196.. option:: --status-interval=time
197
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198 Force a full status dump of cumulative (from job start) values at `time`
199 intervals. This option does *not* provide per-period measurements. So
200 values such as bandwidth are running averages. When the time unit is omitted,
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201 `time` is interpreted in seconds. Note that using this option with
202 ``--output-format=json`` will yield output that technically isn't valid
203 json, since the output will be collated sets of valid json. It will need
204 to be split into valid sets of json after the run.
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205
206.. option:: --section=name
207
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208 Only run specified section `name` in job file. Multiple sections can be specified.
209 The ``--section`` option allows one to combine related jobs into one file.
210 E.g. one job file could define light, moderate, and heavy sections. Tell
211 fio to run only the "heavy" section by giving ``--section=heavy``
212 command line option. One can also specify the "write" operations in one
213 section and "verify" operation in another section. The ``--section`` option
214 only applies to job sections. The reserved *global* section is always
215 parsed and used.
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216
217.. option:: --alloc-size=kb
218
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219 Set the internal smalloc pool size to `kb` in KiB. The
220 ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
221 If running large jobs with randommap enabled, fio can run out of memory.
222 Smalloc is an internal allocator for shared structures from a fixed size
223 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
f80dba8d 224
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225 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
226 in :file:`/tmp`.
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227
228.. option:: --warnings-fatal
229
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230 All fio parser warnings are fatal, causing fio to exit with an
231 error.
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232
233.. option:: --max-jobs=nr
234
f50fbdda 235 Set the maximum number of threads/processes to support to `nr`.
818322cc 236 NOTE: On Linux, it may be necessary to increase the shared-memory
71aa48eb 237 limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
818322cc 238 creating jobs.
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239
240.. option:: --server=args
241
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242 Start a backend server, with `args` specifying what to listen to.
243 See `Client/Server`_ section.
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244
245.. option:: --daemonize=pidfile
246
b034c0dd 247 Background a fio server, writing the pid to the given `pidfile` file.
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248
249.. option:: --client=hostname
250
f50fbdda 251 Instead of running the jobs locally, send and run them on the given `hostname`
71aa48eb 252 or set of `hostname`\s. See `Client/Server`_ section.
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253
254.. option:: --remote-config=file
255
f50fbdda 256 Tell fio server to load this local `file`.
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257
258.. option:: --idle-prof=option
259
b8f7e412 260 Report CPU idleness. `option` is one of the following:
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261
262 **calibrate**
263 Run unit work calibration only and exit.
264
265 **system**
266 Show aggregate system idleness and unit work.
267
268 **percpu**
269 As **system** but also show per CPU idleness.
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270
271.. option:: --inflate-log=log
272
f50fbdda 273 Inflate and output compressed `log`.
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274
275.. option:: --trigger-file=file
276
f50fbdda 277 Execute trigger command when `file` exists.
f80dba8d 278
f50fbdda 279.. option:: --trigger-timeout=time
f80dba8d 280
f50fbdda 281 Execute trigger at this `time`.
f80dba8d 282
f50fbdda 283.. option:: --trigger=command
f80dba8d 284
f50fbdda 285 Set this `command` as local trigger.
f80dba8d 286
f50fbdda 287.. option:: --trigger-remote=command
f80dba8d 288
f50fbdda 289 Set this `command` as remote trigger.
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290
291.. option:: --aux-path=path
292
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293 Use the directory specified by `path` for generated state files instead
294 of the current working directory.
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295
296Any parameters following the options will be assumed to be job files, unless
297they match a job file parameter. Multiple job files can be listed and each job
298file will be regarded as a separate group. Fio will :option:`stonewall`
299execution between each group.
300
301
302Job file format
303---------------
304
305As previously described, fio accepts one or more job files describing what it is
306supposed to do. The job file format is the classic ini file, where the names
c60ebc45 307enclosed in [] brackets define the job name. You are free to use any ASCII name
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308you want, except *global* which has special meaning. Following the job name is
309a sequence of zero or more parameters, one per line, that define the behavior of
310the job. If the first character in a line is a ';' or a '#', the entire line is
311discarded as a comment.
312
313A *global* section sets defaults for the jobs described in that file. A job may
314override a *global* section parameter, and a job file may even have several
315*global* sections if so desired. A job is only affected by a *global* section
316residing above it.
317
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318The :option:`--cmdhelp` option also lists all options. If used with a `command`
319argument, :option:`--cmdhelp` will detail the given `command`.
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320
321See the `examples/` directory for inspiration on how to write job files. Note
322the copyright and license requirements currently apply to `examples/` files.
323
324So let's look at a really simple job file that defines two processes, each
325randomly reading from a 128MiB file:
326
327.. code-block:: ini
328
329 ; -- start job file --
330 [global]
331 rw=randread
332 size=128m
333
334 [job1]
335
336 [job2]
337
338 ; -- end job file --
339
340As you can see, the job file sections themselves are empty as all the described
341parameters are shared. As no :option:`filename` option is given, fio makes up a
342`filename` for each of the jobs as it sees fit. On the command line, this job
343would look as follows::
344
345$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
346
347
348Let's look at an example that has a number of processes writing randomly to
349files:
350
351.. code-block:: ini
352
353 ; -- start job file --
354 [random-writers]
355 ioengine=libaio
356 iodepth=4
357 rw=randwrite
358 bs=32k
359 direct=0
360 size=64m
361 numjobs=4
362 ; -- end job file --
363
364Here we have no *global* section, as we only have one job defined anyway. We
365want to use async I/O here, with a depth of 4 for each file. We also increased
366the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
367jobs. The result is 4 processes each randomly writing to their own 64MiB
368file. Instead of using the above job file, you could have given the parameters
369on the command line. For this case, you would specify::
370
371$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
372
373When fio is utilized as a basis of any reasonably large test suite, it might be
374desirable to share a set of standardized settings across multiple job files.
375Instead of copy/pasting such settings, any section may pull in an external
376:file:`filename.fio` file with *include filename* directive, as in the following
377example::
378
379 ; -- start job file including.fio --
380 [global]
381 filename=/tmp/test
382 filesize=1m
383 include glob-include.fio
384
385 [test]
386 rw=randread
387 bs=4k
388 time_based=1
389 runtime=10
390 include test-include.fio
391 ; -- end job file including.fio --
392
393.. code-block:: ini
394
395 ; -- start job file glob-include.fio --
396 thread=1
397 group_reporting=1
398 ; -- end job file glob-include.fio --
399
400.. code-block:: ini
401
402 ; -- start job file test-include.fio --
403 ioengine=libaio
404 iodepth=4
405 ; -- end job file test-include.fio --
406
407Settings pulled into a section apply to that section only (except *global*
408section). Include directives may be nested in that any included file may contain
409further include directive(s). Include files may not contain [] sections.
410
411
412Environment variables
413~~~~~~~~~~~~~~~~~~~~~
414
415Fio also supports environment variable expansion in job files. Any sub-string of
416the form ``${VARNAME}`` as part of an option value (in other words, on the right
417of the '='), will be expanded to the value of the environment variable called
418`VARNAME`. If no such environment variable is defined, or `VARNAME` is the
419empty string, the empty string will be substituted.
420
421As an example, let's look at a sample fio invocation and job file::
422
423$ SIZE=64m NUMJOBS=4 fio jobfile.fio
424
425.. code-block:: ini
426
427 ; -- start job file --
428 [random-writers]
429 rw=randwrite
430 size=${SIZE}
431 numjobs=${NUMJOBS}
432 ; -- end job file --
433
434This will expand to the following equivalent job file at runtime:
435
436.. code-block:: ini
437
438 ; -- start job file --
439 [random-writers]
440 rw=randwrite
441 size=64m
442 numjobs=4
443 ; -- end job file --
444
445Fio ships with a few example job files, you can also look there for inspiration.
446
447Reserved keywords
448~~~~~~~~~~~~~~~~~
449
450Additionally, fio has a set of reserved keywords that will be replaced
451internally with the appropriate value. Those keywords are:
452
453**$pagesize**
454
455 The architecture page size of the running system.
456
457**$mb_memory**
458
459 Megabytes of total memory in the system.
460
461**$ncpus**
462
463 Number of online available CPUs.
464
465These can be used on the command line or in the job file, and will be
466automatically substituted with the current system values when the job is
467run. Simple math is also supported on these keywords, so you can perform actions
468like::
469
b034c0dd 470 size=8*$mb_memory
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471
472and get that properly expanded to 8 times the size of memory in the machine.
473
474
475Job file parameters
476-------------------
477
478This section describes in details each parameter associated with a job. Some
479parameters take an option of a given type, such as an integer or a
480string. Anywhere a numeric value is required, an arithmetic expression may be
481used, provided it is surrounded by parentheses. Supported operators are:
482
483 - addition (+)
484 - subtraction (-)
485 - multiplication (*)
486 - division (/)
487 - modulus (%)
488 - exponentiation (^)
489
490For time values in expressions, units are microseconds by default. This is
491different than for time values not in expressions (not enclosed in
492parentheses). The following types are used:
493
494
495Parameter types
496~~~~~~~~~~~~~~~
497
498**str**
b034c0dd 499 String: A sequence of alphanumeric characters.
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500
501**time**
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502 Integer with possible time suffix. Without a unit value is interpreted as
503 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
504 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
505 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
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506
507.. _int:
508
509**int**
510 Integer. A whole number value, which may contain an integer prefix
511 and an integer suffix:
512
b034c0dd 513 [*integer prefix*] **number** [*integer suffix*]
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514
515 The optional *integer prefix* specifies the number's base. The default
516 is decimal. *0x* specifies hexadecimal.
517
518 The optional *integer suffix* specifies the number's units, and includes an
519 optional unit prefix and an optional unit. For quantities of data, the
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520 default unit is bytes. For quantities of time, the default unit is seconds
521 unless otherwise specified.
f80dba8d 522
9207a0cb 523 With :option:`kb_base`\=1000, fio follows international standards for unit
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524 prefixes. To specify power-of-10 decimal values defined in the
525 International System of Units (SI):
526
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527 * *K* -- means kilo (K) or 1000
528 * *M* -- means mega (M) or 1000**2
529 * *G* -- means giga (G) or 1000**3
530 * *T* -- means tera (T) or 1000**4
531 * *P* -- means peta (P) or 1000**5
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532
533 To specify power-of-2 binary values defined in IEC 80000-13:
534
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535 * *Ki* -- means kibi (Ki) or 1024
536 * *Mi* -- means mebi (Mi) or 1024**2
537 * *Gi* -- means gibi (Gi) or 1024**3
538 * *Ti* -- means tebi (Ti) or 1024**4
539 * *Pi* -- means pebi (Pi) or 1024**5
f80dba8d 540
9207a0cb 541 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
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542 from those specified in the SI and IEC 80000-13 standards to provide
543 compatibility with old scripts. For example, 4k means 4096.
544
545 For quantities of data, an optional unit of 'B' may be included
b8f7e412 546 (e.g., 'kB' is the same as 'k').
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547
548 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
549 not milli). 'b' and 'B' both mean byte, not bit.
550
9207a0cb 551 Examples with :option:`kb_base`\=1000:
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552
553 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
554 * *1 MiB*: 1048576, 1mi, 1024ki
555 * *1 MB*: 1000000, 1m, 1000k
556 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
557 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
558
9207a0cb 559 Examples with :option:`kb_base`\=1024 (default):
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560
561 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
562 * *1 MiB*: 1048576, 1m, 1024k
563 * *1 MB*: 1000000, 1mi, 1000ki
564 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
565 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
566
567 To specify times (units are not case sensitive):
568
569 * *D* -- means days
570 * *H* -- means hours
4502cb42 571 * *M* -- means minutes
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572 * *s* -- or sec means seconds (default)
573 * *ms* -- or *msec* means milliseconds
574 * *us* -- or *usec* means microseconds
575
576 If the option accepts an upper and lower range, use a colon ':' or
577 minus '-' to separate such values. See :ref:`irange <irange>`.
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578 If the lower value specified happens to be larger than the upper value
579 the two values are swapped.
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580
581.. _bool:
582
583**bool**
584 Boolean. Usually parsed as an integer, however only defined for
585 true and false (1 and 0).
586
587.. _irange:
588
589**irange**
590 Integer range with suffix. Allows value range to be given, such as
c60ebc45 591 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
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592 option allows two sets of ranges, they can be specified with a ',' or '/'
593 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
594
595**float_list**
596 A list of floating point numbers, separated by a ':' character.
597
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598With the above in mind, here follows the complete list of fio job parameters.
599
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600
601Units
602~~~~~
603
604.. option:: kb_base=int
605
606 Select the interpretation of unit prefixes in input parameters.
607
608 **1000**
609 Inputs comply with IEC 80000-13 and the International
610 System of Units (SI). Use:
611
612 - power-of-2 values with IEC prefixes (e.g., KiB)
613 - power-of-10 values with SI prefixes (e.g., kB)
614
615 **1024**
616 Compatibility mode (default). To avoid breaking old scripts:
617
618 - power-of-2 values with SI prefixes
619 - power-of-10 values with IEC prefixes
620
621 See :option:`bs` for more details on input parameters.
622
623 Outputs always use correct prefixes. Most outputs include both
624 side-by-side, like::
625
626 bw=2383.3kB/s (2327.4KiB/s)
627
628 If only one value is reported, then kb_base selects the one to use:
629
630 **1000** -- SI prefixes
631
632 **1024** -- IEC prefixes
633
634.. option:: unit_base=int
635
636 Base unit for reporting. Allowed values are:
637
638 **0**
639 Use auto-detection (default).
640 **8**
641 Byte based.
642 **1**
643 Bit based.
644
645
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646Job description
647~~~~~~~~~~~~~~~
648
649.. option:: name=str
650
651 ASCII name of the job. This may be used to override the name printed by fio
652 for this job. Otherwise the job name is used. On the command line this
653 parameter has the special purpose of also signaling the start of a new job.
654
655.. option:: description=str
656
657 Text description of the job. Doesn't do anything except dump this text
658 description when this job is run. It's not parsed.
659
660.. option:: loops=int
661
662 Run the specified number of iterations of this job. Used to repeat the same
663 workload a given number of times. Defaults to 1.
664
665.. option:: numjobs=int
666
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667 Create the specified number of clones of this job. Each clone of job
668 is spawned as an independent thread or process. May be used to setup a
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669 larger number of threads/processes doing the same thing. Each thread is
670 reported separately; to see statistics for all clones as a whole, use
671 :option:`group_reporting` in conjunction with :option:`new_group`.
a47b697c 672 See :option:`--max-jobs`. Default: 1.
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673
674
675Time related parameters
676~~~~~~~~~~~~~~~~~~~~~~~
677
678.. option:: runtime=time
679
f75ede1d 680 Tell fio to terminate processing after the specified period of time. It
f80dba8d 681 can be quite hard to determine for how long a specified job will run, so
f75ede1d 682 this parameter is handy to cap the total runtime to a given time. When
804c0839 683 the unit is omitted, the value is interpreted in seconds.
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684
685.. option:: time_based
686
687 If set, fio will run for the duration of the :option:`runtime` specified
688 even if the file(s) are completely read or written. It will simply loop over
689 the same workload as many times as the :option:`runtime` allows.
690
a881438b 691.. option:: startdelay=irange(time)
f80dba8d 692
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693 Delay the start of job for the specified amount of time. Can be a single
694 value or a range. When given as a range, each thread will choose a value
695 randomly from within the range. Value is in seconds if a unit is omitted.
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696
697.. option:: ramp_time=time
698
699 If set, fio will run the specified workload for this amount of time before
700 logging any performance numbers. Useful for letting performance settle
701 before logging results, thus minimizing the runtime required for stable
702 results. Note that the ``ramp_time`` is considered lead in time for a job,
703 thus it will increase the total runtime if a special timeout or
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704 :option:`runtime` is specified. When the unit is omitted, the value is
705 given in seconds.
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706
707.. option:: clocksource=str
708
709 Use the given clocksource as the base of timing. The supported options are:
710
711 **gettimeofday**
712 :manpage:`gettimeofday(2)`
713
714 **clock_gettime**
715 :manpage:`clock_gettime(2)`
716
717 **cpu**
718 Internal CPU clock source
719
720 cpu is the preferred clocksource if it is reliable, as it is very fast (and
721 fio is heavy on time calls). Fio will automatically use this clocksource if
722 it's supported and considered reliable on the system it is running on,
723 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
724 means supporting TSC Invariant.
725
726.. option:: gtod_reduce=bool
727
728 Enable all of the :manpage:`gettimeofday(2)` reducing options
f75ede1d 729 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
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730 reduce precision of the timeout somewhat to really shrink the
731 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
732 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
733 time keeping was enabled.
734
735.. option:: gtod_cpu=int
736
737 Sometimes it's cheaper to dedicate a single thread of execution to just
738 getting the current time. Fio (and databases, for instance) are very
739 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
740 one CPU aside for doing nothing but logging current time to a shared memory
741 location. Then the other threads/processes that run I/O workloads need only
742 copy that segment, instead of entering the kernel with a
743 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
744 calls will be excluded from other uses. Fio will manually clear it from the
745 CPU mask of other jobs.
746
747
748Target file/device
749~~~~~~~~~~~~~~~~~~
750
751.. option:: directory=str
752
753 Prefix filenames with this directory. Used to place files in a different
754 location than :file:`./`. You can specify a number of directories by
755 separating the names with a ':' character. These directories will be
02dd2689 756 assigned equally distributed to job clones created by :option:`numjobs` as
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757 long as they are using generated filenames. If specific `filename(s)` are
758 set fio will use the first listed directory, and thereby matching the
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759 `filename` semantic (which generates a file for each clone if not
760 specified, but lets all clones use the same file if set).
f80dba8d 761
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762 See the :option:`filename` option for information on how to escape "``:``" and
763 "``\``" characters within the directory path itself.
f80dba8d 764
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765 Note: To control the directory fio will use for internal state files
766 use :option:`--aux-path`.
767
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768.. option:: filename=str
769
770 Fio normally makes up a `filename` based on the job name, thread number, and
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771 file number (see :option:`filename_format`). If you want to share files
772 between threads in a job or several
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773 jobs with fixed file paths, specify a `filename` for each of them to override
774 the default. If the ioengine is file based, you can specify a number of files
775 by separating the names with a ':' colon. So if you wanted a job to open
776 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
777 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
778 specified, :option:`nrfiles` is ignored. The size of regular files specified
02dd2689 779 by this option will be :option:`size` divided by number of files unless an
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780 explicit size is specified by :option:`filesize`.
781
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782 Each colon and backslash in the wanted path must be escaped with a ``\``
783 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
784 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
785 :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
786
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787 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
788 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
789 Note: Windows and FreeBSD prevent write access to areas
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790 of the disk containing in-use data (e.g. filesystems).
791
792 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
793 of the two depends on the read/write direction set.
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794
795.. option:: filename_format=str
796
797 If sharing multiple files between jobs, it is usually necessary to have fio
798 generate the exact names that you want. By default, fio will name a file
799 based on the default file format specification of
800 :file:`jobname.jobnumber.filenumber`. With this option, that can be
801 customized. Fio will recognize and replace the following keywords in this
802 string:
803
804 **$jobname**
805 The name of the worker thread or process.
806 **$jobnum**
807 The incremental number of the worker thread or process.
808 **$filenum**
809 The incremental number of the file for that worker thread or
810 process.
811
812 To have dependent jobs share a set of files, this option can be set to have
813 fio generate filenames that are shared between the two. For instance, if
814 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
815 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
816 will be used if no other format specifier is given.
817
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818 If you specify a path then the directories will be created up to the
819 main directory for the file. So for example if you specify
820 ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
821 created before the file setup part of the job. If you specify
822 :option:`directory` then the path will be relative that directory,
823 otherwise it is treated as the absolute path.
824
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825.. option:: unique_filename=bool
826
827 To avoid collisions between networked clients, fio defaults to prefixing any
828 generated filenames (with a directory specified) with the source of the
829 client connecting. To disable this behavior, set this option to 0.
830
831.. option:: opendir=str
832
833 Recursively open any files below directory `str`.
834
835.. option:: lockfile=str
836
837 Fio defaults to not locking any files before it does I/O to them. If a file
838 or file descriptor is shared, fio can serialize I/O to that file to make the
839 end result consistent. This is usual for emulating real workloads that share
840 files. The lock modes are:
841
842 **none**
843 No locking. The default.
844 **exclusive**
845 Only one thread or process may do I/O at a time, excluding all
846 others.
847 **readwrite**
848 Read-write locking on the file. Many readers may
849 access the file at the same time, but writes get exclusive access.
850
851.. option:: nrfiles=int
852
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853 Number of files to use for this job. Defaults to 1. The size of files
854 will be :option:`size` divided by this unless explicit size is specified by
855 :option:`filesize`. Files are created for each thread separately, and each
856 file will have a file number within its name by default, as explained in
857 :option:`filename` section.
858
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859
860.. option:: openfiles=int
861
862 Number of files to keep open at the same time. Defaults to the same as
863 :option:`nrfiles`, can be set smaller to limit the number simultaneous
864 opens.
865
866.. option:: file_service_type=str
867
868 Defines how fio decides which file from a job to service next. The following
869 types are defined:
870
871 **random**
872 Choose a file at random.
873
874 **roundrobin**
875 Round robin over opened files. This is the default.
876
877 **sequential**
878 Finish one file before moving on to the next. Multiple files can
f50fbdda 879 still be open depending on :option:`openfiles`.
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880
881 **zipf**
c60ebc45 882 Use a *Zipf* distribution to decide what file to access.
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883
884 **pareto**
c60ebc45 885 Use a *Pareto* distribution to decide what file to access.
f80dba8d 886
dd3503d3 887 **normal**
c60ebc45 888 Use a *Gaussian* (normal) distribution to decide what file to
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889 access.
890
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891 **gauss**
892 Alias for normal.
893
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894 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
895 tell fio how many I/Os to issue before switching to a new file. For example,
896 specifying ``file_service_type=random:8`` would cause fio to issue
897 8 I/Os before selecting a new file at random. For the non-uniform
898 distributions, a floating point postfix can be given to influence how the
899 distribution is skewed. See :option:`random_distribution` for a description
900 of how that would work.
901
902.. option:: ioscheduler=str
903
904 Attempt to switch the device hosting the file to the specified I/O scheduler
905 before running.
906
907.. option:: create_serialize=bool
908
909 If true, serialize the file creation for the jobs. This may be handy to
910 avoid interleaving of data files, which may greatly depend on the filesystem
a47b697c 911 used and even the number of processors in the system. Default: true.
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912
913.. option:: create_fsync=bool
914
22413915 915 :manpage:`fsync(2)` the data file after creation. This is the default.
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916
917.. option:: create_on_open=bool
918
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919 If true, don't pre-create files but allow the job's open() to create a file
920 when it's time to do I/O. Default: false -- pre-create all necessary files
921 when the job starts.
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922
923.. option:: create_only=bool
924
925 If true, fio will only run the setup phase of the job. If files need to be
4502cb42 926 laid out or updated on disk, only that will be done -- the actual job contents
a47b697c 927 are not executed. Default: false.
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928
929.. option:: allow_file_create=bool
930
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931 If true, fio is permitted to create files as part of its workload. If this
932 option is false, then fio will error out if
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933 the files it needs to use don't already exist. Default: true.
934
935.. option:: allow_mounted_write=bool
936
c60ebc45 937 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
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938 to what appears to be a mounted device or partition. This should help catch
939 creating inadvertently destructive tests, not realizing that the test will
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940 destroy data on the mounted file system. Note that some platforms don't allow
941 writing against a mounted device regardless of this option. Default: false.
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942
943.. option:: pre_read=bool
944
945 If this is given, files will be pre-read into memory before starting the
946 given I/O operation. This will also clear the :option:`invalidate` flag,
947 since it is pointless to pre-read and then drop the cache. This will only
948 work for I/O engines that are seek-able, since they allow you to read the
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949 same data multiple times. Thus it will not work on non-seekable I/O engines
950 (e.g. network, splice). Default: false.
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951
952.. option:: unlink=bool
953
954 Unlink the job files when done. Not the default, as repeated runs of that
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955 job would then waste time recreating the file set again and again. Default:
956 false.
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957
958.. option:: unlink_each_loop=bool
959
a47b697c 960 Unlink job files after each iteration or loop. Default: false.
f80dba8d 961
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962.. option:: zonemode=str
963
964 Accepted values are:
965
966 **none**
967 The :option:`zonerange`, :option:`zonesize` and
968 :option:`zoneskip` parameters are ignored.
969 **strided**
970 I/O happens in a single zone until
971 :option:`zonesize` bytes have been transferred.
972 After that number of bytes has been
973 transferred processing of the next zone
974 starts.
975 **zbd**
976 Zoned block device mode. I/O happens
977 sequentially in each zone, even if random I/O
978 has been selected. Random I/O happens across
979 all zones instead of being restricted to a
980 single zone. The :option:`zoneskip` parameter
981 is ignored. :option:`zonerange` and
982 :option:`zonesize` must be identical.
983
5faddc64 984.. option:: zonerange=int
f80dba8d 985
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986 Size of a single zone. See also :option:`zonesize` and
987 :option:`zoneskip`.
f80dba8d 988
5faddc64 989.. option:: zonesize=int
f80dba8d 990
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991 For :option:`zonemode` =strided, this is the number of bytes to
992 transfer before skipping :option:`zoneskip` bytes. If this parameter
993 is smaller than :option:`zonerange` then only a fraction of each zone
994 with :option:`zonerange` bytes will be accessed. If this parameter is
995 larger than :option:`zonerange` then each zone will be accessed
996 multiple times before skipping to the next zone.
997
998 For :option:`zonemode` =zbd, this is the size of a single zone. The
999 :option:`zonerange` parameter is ignored in this mode.
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1000
1001.. option:: zoneskip=int
1002
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1003 For :option:`zonemode` =strided, the number of bytes to skip after
1004 :option:`zonesize` bytes of data have been transferred. This parameter
1005 must be zero for :option:`zonemode` =zbd.
f80dba8d 1006
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1007.. option:: read_beyond_wp=bool
1008
1009 This parameter applies to :option:`zonemode` =zbd only.
1010
1011 Zoned block devices are block devices that consist of multiple zones.
1012 Each zone has a type, e.g. conventional or sequential. A conventional
1013 zone can be written at any offset that is a multiple of the block
1014 size. Sequential zones must be written sequentially. The position at
1015 which a write must occur is called the write pointer. A zoned block
1016 device can be either drive managed, host managed or host aware. For
1017 host managed devices the host must ensure that writes happen
1018 sequentially. Fio recognizes host managed devices and serializes
1019 writes to sequential zones for these devices.
1020
1021 If a read occurs in a sequential zone beyond the write pointer then
1022 the zoned block device will complete the read without reading any data
1023 from the storage medium. Since such reads lead to unrealistically high
1024 bandwidth and IOPS numbers fio only reads beyond the write pointer if
1025 explicitly told to do so. Default: false.
1026
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1027.. option:: max_open_zones=int
1028
1029 When running a random write test across an entire drive many more
1030 zones will be open than in a typical application workload. Hence this
1031 command line option that allows to limit the number of open zones. The
1032 number of open zones is defined as the number of zones to which write
1033 commands are issued.
1034
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1035.. option:: zone_reset_threshold=float
1036
1037 A number between zero and one that indicates the ratio of logical
1038 blocks with data to the total number of logical blocks in the test
1039 above which zones should be reset periodically.
1040
1041.. option:: zone_reset_frequency=float
1042
1043 A number between zero and one that indicates how often a zone reset
1044 should be issued if the zone reset threshold has been exceeded. A zone
1045 reset is submitted after each (1 / zone_reset_frequency) write
1046 requests. This and the previous parameter can be used to simulate
1047 garbage collection activity.
1048
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1049
1050I/O type
1051~~~~~~~~
1052
1053.. option:: direct=bool
1054
1055 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
8e889110 1056 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
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1057 ioengines don't support direct I/O. Default: false.
1058
1059.. option:: atomic=bool
1060
1061 If value is true, attempt to use atomic direct I/O. Atomic writes are
1062 guaranteed to be stable once acknowledged by the operating system. Only
1063 Linux supports O_ATOMIC right now.
1064
1065.. option:: buffered=bool
1066
1067 If value is true, use buffered I/O. This is the opposite of the
1068 :option:`direct` option. Defaults to true.
1069
1070.. option:: readwrite=str, rw=str
1071
1072 Type of I/O pattern. Accepted values are:
1073
1074 **read**
1075 Sequential reads.
1076 **write**
1077 Sequential writes.
1078 **trim**
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1079 Sequential trims (Linux block devices and SCSI
1080 character devices only).
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1081 **randread**
1082 Random reads.
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1083 **randwrite**
1084 Random writes.
f80dba8d 1085 **randtrim**
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1086 Random trims (Linux block devices and SCSI
1087 character devices only).
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1088 **rw,readwrite**
1089 Sequential mixed reads and writes.
1090 **randrw**
1091 Random mixed reads and writes.
1092 **trimwrite**
1093 Sequential trim+write sequences. Blocks will be trimmed first,
1094 then the same blocks will be written to.
1095
1096 Fio defaults to read if the option is not specified. For the mixed I/O
1097 types, the default is to split them 50/50. For certain types of I/O the
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1098 result may still be skewed a bit, since the speed may be different.
1099
1100 It is possible to specify the number of I/Os to do before getting a new
1101 offset by appending ``:<nr>`` to the end of the string given. For a
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1102 random read, it would look like ``rw=randread:8`` for passing in an offset
1103 modifier with a value of 8. If the suffix is used with a sequential I/O
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1104 pattern, then the *<nr>* value specified will be **added** to the generated
1105 offset for each I/O turning sequential I/O into sequential I/O with holes.
1106 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1107 the :option:`rw_sequencer` option.
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1108
1109.. option:: rw_sequencer=str
1110
1111 If an offset modifier is given by appending a number to the ``rw=<str>``
1112 line, then this option controls how that number modifies the I/O offset
1113 being generated. Accepted values are:
1114
1115 **sequential**
1116 Generate sequential offset.
1117 **identical**
1118 Generate the same offset.
1119
1120 ``sequential`` is only useful for random I/O, where fio would normally
c60ebc45 1121 generate a new random offset for every I/O. If you append e.g. 8 to randread,
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1122 you would get a new random offset for every 8 I/Os. The result would be a
1123 seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
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1124 to specify that. As sequential I/O is already sequential, setting
1125 ``sequential`` for that would not result in any differences. ``identical``
1126 behaves in a similar fashion, except it sends the same offset 8 number of
1127 times before generating a new offset.
1128
1129.. option:: unified_rw_reporting=bool
1130
1131 Fio normally reports statistics on a per data direction basis, meaning that
1132 reads, writes, and trims are accounted and reported separately. If this
1133 option is set fio sums the results and report them as "mixed" instead.
1134
1135.. option:: randrepeat=bool
1136
1137 Seed the random number generator used for random I/O patterns in a
1138 predictable way so the pattern is repeatable across runs. Default: true.
1139
1140.. option:: allrandrepeat=bool
1141
1142 Seed all random number generators in a predictable way so results are
1143 repeatable across runs. Default: false.
1144
1145.. option:: randseed=int
1146
1147 Seed the random number generators based on this seed value, to be able to
1148 control what sequence of output is being generated. If not set, the random
1149 sequence depends on the :option:`randrepeat` setting.
1150
1151.. option:: fallocate=str
1152
1153 Whether pre-allocation is performed when laying down files.
1154 Accepted values are:
1155
1156 **none**
1157 Do not pre-allocate space.
1158
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1159 **native**
1160 Use a platform's native pre-allocation call but fall back to
1161 **none** behavior if it fails/is not implemented.
1162
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1163 **posix**
1164 Pre-allocate via :manpage:`posix_fallocate(3)`.
1165
1166 **keep**
1167 Pre-allocate via :manpage:`fallocate(2)` with
1168 FALLOC_FL_KEEP_SIZE set.
1169
1170 **0**
1171 Backward-compatible alias for **none**.
1172
1173 **1**
1174 Backward-compatible alias for **posix**.
1175
1176 May not be available on all supported platforms. **keep** is only available
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1177 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1178 because ZFS doesn't support pre-allocation. Default: **native** if any
1179 pre-allocation methods are available, **none** if not.
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1180
1181.. option:: fadvise_hint=str
1182
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1183 Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to
1184 advise the kernel on what I/O patterns are likely to be issued.
1185 Accepted values are:
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1186
1187 **0**
1188 Backwards-compatible hint for "no hint".
1189
1190 **1**
1191 Backwards compatible hint for "advise with fio workload type". This
1192 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1193 for a sequential workload.
1194
1195 **sequential**
1196 Advise using **FADV_SEQUENTIAL**.
1197
1198 **random**
1199 Advise using **FADV_RANDOM**.
1200
8f4b9f24 1201.. option:: write_hint=str
f80dba8d 1202
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1203 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1204 from a write. Only supported on Linux, as of version 4.13. Accepted
1205 values are:
1206
1207 **none**
1208 No particular life time associated with this file.
1209
1210 **short**
1211 Data written to this file has a short life time.
1212
1213 **medium**
1214 Data written to this file has a medium life time.
1215
1216 **long**
1217 Data written to this file has a long life time.
1218
1219 **extreme**
1220 Data written to this file has a very long life time.
1221
1222 The values are all relative to each other, and no absolute meaning
1223 should be associated with them.
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1224
1225.. option:: offset=int
1226
82dbb8cb 1227 Start I/O at the provided offset in the file, given as either a fixed size in
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1228 bytes or a percentage. If a percentage is given, the generated offset will be
1229 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1230 provided. Data before the given offset will not be touched. This
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BW
1231 effectively caps the file size at `real_size - offset`. Can be combined with
1232 :option:`size` to constrain the start and end range of the I/O workload.
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1233 A percentage can be specified by a number between 1 and 100 followed by '%',
1234 for example, ``offset=20%`` to specify 20%.
f80dba8d 1235
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1236.. option:: offset_align=int
1237
1238 If set to non-zero value, the byte offset generated by a percentage ``offset``
1239 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1240 offset is aligned to the minimum block size.
1241
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1242.. option:: offset_increment=int
1243
1244 If this is provided, then the real offset becomes `offset + offset_increment
1245 * thread_number`, where the thread number is a counter that starts at 0 and
1246 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1247 specified). This option is useful if there are several jobs which are
1248 intended to operate on a file in parallel disjoint segments, with even
1249 spacing between the starting points.
1250
1251.. option:: number_ios=int
1252
c60ebc45 1253 Fio will normally perform I/Os until it has exhausted the size of the region
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1254 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1255 condition). With this setting, the range/size can be set independently of
c60ebc45 1256 the number of I/Os to perform. When fio reaches this number, it will exit
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1257 normally and report status. Note that this does not extend the amount of I/O
1258 that will be done, it will only stop fio if this condition is met before
1259 other end-of-job criteria.
1260
1261.. option:: fsync=int
1262
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1263 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1264 the dirty data for every number of blocks given. For example, if you give 32
1265 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1266 using non-buffered I/O, we may not sync the file. The exception is the sg
1267 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1268 means fio does not periodically issue and wait for a sync to complete. Also
1269 see :option:`end_fsync` and :option:`fsync_on_close`.
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1270
1271.. option:: fdatasync=int
1272
1273 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
000a5f1c 1274 not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
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1275 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1276 Defaults to 0, which means fio does not periodically issue and wait for a
1277 data-only sync to complete.
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1278
1279.. option:: write_barrier=int
1280
2831be97 1281 Make every `N-th` write a barrier write.
f80dba8d 1282
f50fbdda 1283.. option:: sync_file_range=str:int
f80dba8d 1284
f50fbdda 1285 Use :manpage:`sync_file_range(2)` for every `int` number of write
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1286 operations. Fio will track range of writes that have happened since the last
1287 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1288
1289 **wait_before**
1290 SYNC_FILE_RANGE_WAIT_BEFORE
1291 **write**
1292 SYNC_FILE_RANGE_WRITE
1293 **wait_after**
1294 SYNC_FILE_RANGE_WAIT_AFTER
1295
1296 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1297 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1298 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1299 Linux specific.
1300
1301.. option:: overwrite=bool
1302
1303 If true, writes to a file will always overwrite existing data. If the file
1304 doesn't already exist, it will be created before the write phase begins. If
1305 the file exists and is large enough for the specified write phase, nothing
a47b697c 1306 will be done. Default: false.
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1307
1308.. option:: end_fsync=bool
1309
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1310 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1311 Default: false.
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1312
1313.. option:: fsync_on_close=bool
1314
1315 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
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1316 from :option:`end_fsync` in that it will happen on every file close, not
1317 just at the end of the job. Default: false.
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1318
1319.. option:: rwmixread=int
1320
1321 Percentage of a mixed workload that should be reads. Default: 50.
1322
1323.. option:: rwmixwrite=int
1324
1325 Percentage of a mixed workload that should be writes. If both
1326 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1327 add up to 100%, the latter of the two will be used to override the
1328 first. This may interfere with a given rate setting, if fio is asked to
1329 limit reads or writes to a certain rate. If that is the case, then the
1330 distribution may be skewed. Default: 50.
1331
1332.. option:: random_distribution=str:float[,str:float][,str:float]
1333
1334 By default, fio will use a completely uniform random distribution when asked
1335 to perform random I/O. Sometimes it is useful to skew the distribution in
1336 specific ways, ensuring that some parts of the data is more hot than others.
1337 fio includes the following distribution models:
1338
1339 **random**
1340 Uniform random distribution
1341
1342 **zipf**
1343 Zipf distribution
1344
1345 **pareto**
1346 Pareto distribution
1347
b2f4b559 1348 **normal**
c60ebc45 1349 Normal (Gaussian) distribution
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1350
1351 **zoned**
1352 Zoned random distribution
1353
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1354 **zoned_abs**
1355 Zone absolute random distribution
1356
f80dba8d 1357 When using a **zipf** or **pareto** distribution, an input value is also
f50fbdda 1358 needed to define the access pattern. For **zipf**, this is the `Zipf
c60ebc45 1359 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
f50fbdda 1360 program, :command:`fio-genzipf`, that can be used visualize what the given input
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1361 values will yield in terms of hit rates. If you wanted to use **zipf** with
1362 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1363 option. If a non-uniform model is used, fio will disable use of the random
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1364 map. For the **normal** distribution, a normal (Gaussian) deviation is
1365 supplied as a value between 0 and 100.
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1366
1367 For a **zoned** distribution, fio supports specifying percentages of I/O
1368 access that should fall within what range of the file or device. For
1369 example, given a criteria of:
1370
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1371 * 60% of accesses should be to the first 10%
1372 * 30% of accesses should be to the next 20%
1373 * 8% of accesses should be to the next 30%
1374 * 2% of accesses should be to the next 40%
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1375
1376 we can define that through zoning of the random accesses. For the above
1377 example, the user would do::
1378
1379 random_distribution=zoned:60/10:30/20:8/30:2/40
1380
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1381 A **zoned_abs** distribution works exactly like the **zoned**, except
1382 that it takes absolute sizes. For example, let's say you wanted to
1383 define access according to the following criteria:
1384
1385 * 60% of accesses should be to the first 20G
1386 * 30% of accesses should be to the next 100G
1387 * 10% of accesses should be to the next 500G
1388
1389 we can define an absolute zoning distribution with:
1390
1391 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1392
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1393 For both **zoned** and **zoned_abs**, fio supports defining up to
1394 256 separate zones.
1395
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1396 Similarly to how :option:`bssplit` works for setting ranges and
1397 percentages of block sizes. Like :option:`bssplit`, it's possible to
1398 specify separate zones for reads, writes, and trims. If just one set
1399 is given, it'll apply to all of them. This goes for both **zoned**
1400 **zoned_abs** distributions.
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1401
1402.. option:: percentage_random=int[,int][,int]
1403
1404 For a random workload, set how big a percentage should be random. This
1405 defaults to 100%, in which case the workload is fully random. It can be set
1406 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1407 sequential. Any setting in between will result in a random mix of sequential
1408 and random I/O, at the given percentages. Comma-separated values may be
1409 specified for reads, writes, and trims as described in :option:`blocksize`.
1410
1411.. option:: norandommap
1412
1413 Normally fio will cover every block of the file when doing random I/O. If
1414 this option is given, fio will just get a new random offset without looking
1415 at past I/O history. This means that some blocks may not be read or written,
1416 and that some blocks may be read/written more than once. If this option is
1417 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1418 only intact blocks are verified, i.e., partially-overwritten blocks are
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1419 ignored. With an async I/O engine and an I/O depth > 1, it is possible for
1420 the same block to be overwritten, which can cause verification errors. Either
1421 do not use norandommap in this case, or also use the lfsr random generator.
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1422
1423.. option:: softrandommap=bool
1424
1425 See :option:`norandommap`. If fio runs with the random block map enabled and
1426 it fails to allocate the map, if this option is set it will continue without
1427 a random block map. As coverage will not be as complete as with random maps,
1428 this option is disabled by default.
1429
1430.. option:: random_generator=str
1431
f50fbdda 1432 Fio supports the following engines for generating I/O offsets for random I/O:
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1433
1434 **tausworthe**
f50fbdda 1435 Strong 2^88 cycle random number generator.
f80dba8d 1436 **lfsr**
f50fbdda 1437 Linear feedback shift register generator.
f80dba8d 1438 **tausworthe64**
f50fbdda 1439 Strong 64-bit 2^258 cycle random number generator.
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1440
1441 **tausworthe** is a strong random number generator, but it requires tracking
1442 on the side if we want to ensure that blocks are only read or written
f50fbdda 1443 once. **lfsr** guarantees that we never generate the same offset twice, and
f80dba8d 1444 it's also less computationally expensive. It's not a true random generator,
f50fbdda 1445 however, though for I/O purposes it's typically good enough. **lfsr** only
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1446 works with single block sizes, not with workloads that use multiple block
1447 sizes. If used with such a workload, fio may read or write some blocks
1448 multiple times. The default value is **tausworthe**, unless the required
1449 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1450 selected automatically.
1451
1452
1453Block size
1454~~~~~~~~~~
1455
1456.. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1457
1458 The block size in bytes used for I/O units. Default: 4096. A single value
1459 applies to reads, writes, and trims. Comma-separated values may be
1460 specified for reads, writes, and trims. A value not terminated in a comma
1461 applies to subsequent types.
1462
1463 Examples:
1464
1465 **bs=256k**
1466 means 256k for reads, writes and trims.
1467
1468 **bs=8k,32k**
1469 means 8k for reads, 32k for writes and trims.
1470
1471 **bs=8k,32k,**
1472 means 8k for reads, 32k for writes, and default for trims.
1473
1474 **bs=,8k**
1475 means default for reads, 8k for writes and trims.
1476
1477 **bs=,8k,**
b443ae44 1478 means default for reads, 8k for writes, and default for trims.
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1479
1480.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1481
1482 A range of block sizes in bytes for I/O units. The issued I/O unit will
1483 always be a multiple of the minimum size, unless
1484 :option:`blocksize_unaligned` is set.
1485
1486 Comma-separated ranges may be specified for reads, writes, and trims as
1487 described in :option:`blocksize`.
1488
1489 Example: ``bsrange=1k-4k,2k-8k``.
1490
1491.. option:: bssplit=str[,str][,str]
1492
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JA
1493 Sometimes you want even finer grained control of the block sizes
1494 issued, not just an even split between them. This option allows you to
1495 weight various block sizes, so that you are able to define a specific
1496 amount of block sizes issued. The format for this option is::
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1497
1498 bssplit=blocksize/percentage:blocksize/percentage
1499
6a16ece8
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1500 for as many block sizes as needed. So if you want to define a workload
1501 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1502 write::
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1503
1504 bssplit=4k/10:64k/50:32k/40
1505
6a16ece8
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1506 Ordering does not matter. If the percentage is left blank, fio will
1507 fill in the remaining values evenly. So a bssplit option like this one::
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1508
1509 bssplit=4k/50:1k/:32k/
1510
6a16ece8
JA
1511 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1512 add up to 100, if bssplit is given a range that adds up to more, it
1513 will error out.
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1514
1515 Comma-separated values may be specified for reads, writes, and trims as
1516 described in :option:`blocksize`.
1517
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JA
1518 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1519 having 90% 4k writes and 10% 8k writes, you would specify::
f80dba8d 1520
cf04b906 1521 bssplit=2k/50:4k/50,4k/90:8k/10
f80dba8d 1522
6a16ece8
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1523 Fio supports defining up to 64 different weights for each data
1524 direction.
1525
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1526.. option:: blocksize_unaligned, bs_unaligned
1527
1528 If set, fio will issue I/O units with any size within
1529 :option:`blocksize_range`, not just multiples of the minimum size. This
1530 typically won't work with direct I/O, as that normally requires sector
1531 alignment.
1532
589e88b7 1533.. option:: bs_is_seq_rand=bool
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1534
1535 If this option is set, fio will use the normal read,write blocksize settings
1536 as sequential,random blocksize settings instead. Any random read or write
1537 will use the WRITE blocksize settings, and any sequential read or write will
1538 use the READ blocksize settings.
1539
1540.. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1541
1542 Boundary to which fio will align random I/O units. Default:
1543 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1544 I/O, though it usually depends on the hardware block size. This option is
1545 mutually exclusive with using a random map for files, so it will turn off
1546 that option. Comma-separated values may be specified for reads, writes, and
1547 trims as described in :option:`blocksize`.
1548
1549
1550Buffers and memory
1551~~~~~~~~~~~~~~~~~~
1552
1553.. option:: zero_buffers
1554
1555 Initialize buffers with all zeros. Default: fill buffers with random data.
1556
1557.. option:: refill_buffers
1558
1559 If this option is given, fio will refill the I/O buffers on every
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1560 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1561 naturally. Defaults to being unset i.e., the buffer is only filled at
1562 init time and the data in it is reused when possible but if any of
1563 :option:`verify`, :option:`buffer_compress_percentage` or
1564 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1565 automatically enabled.
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1566
1567.. option:: scramble_buffers=bool
1568
1569 If :option:`refill_buffers` is too costly and the target is using data
1570 deduplication, then setting this option will slightly modify the I/O buffer
1571 contents to defeat normal de-dupe attempts. This is not enough to defeat
1572 more clever block compression attempts, but it will stop naive dedupe of
1573 blocks. Default: true.
1574
1575.. option:: buffer_compress_percentage=int
1576
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1577 If this is set, then fio will attempt to provide I/O buffer content
1578 (on WRITEs) that compresses to the specified level. Fio does this by
1579 providing a mix of random data followed by fixed pattern data. The
1580 fixed pattern is either zeros, or the pattern specified by
1581 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1582 might skew the compression ratio slightly. Setting
1583 `buffer_compress_percentage` to a value other than 100 will also
1584 enable :option:`refill_buffers` in order to reduce the likelihood that
1585 adjacent blocks are so similar that they over compress when seen
1586 together. See :option:`buffer_compress_chunk` for how to set a finer or
1587 coarser granularity for the random/fixed data region. Defaults to unset
1588 i.e., buffer data will not adhere to any compression level.
f80dba8d
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1589
1590.. option:: buffer_compress_chunk=int
1591
72592780
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1592 This setting allows fio to manage how big the random/fixed data region
1593 is when using :option:`buffer_compress_percentage`. When
1594 `buffer_compress_chunk` is set to some non-zero value smaller than the
1595 block size, fio can repeat the random/fixed region throughout the I/O
1596 buffer at the specified interval (which particularly useful when
1597 bigger block sizes are used for a job). When set to 0, fio will use a
1598 chunk size that matches the block size resulting in a single
1599 random/fixed region within the I/O buffer. Defaults to 512. When the
1600 unit is omitted, the value is interpreted in bytes.
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1601
1602.. option:: buffer_pattern=str
1603
a1554f65
SB
1604 If set, fio will fill the I/O buffers with this pattern or with the contents
1605 of a file. If not set, the contents of I/O buffers are defined by the other
1606 options related to buffer contents. The setting can be any pattern of bytes,
1607 and can be prefixed with 0x for hex values. It may also be a string, where
1608 the string must then be wrapped with ``""``. Or it may also be a filename,
1609 where the filename must be wrapped with ``''`` in which case the file is
1610 opened and read. Note that not all the file contents will be read if that
1611 would cause the buffers to overflow. So, for example::
1612
1613 buffer_pattern='filename'
1614
1615 or::
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1616
1617 buffer_pattern="abcd"
1618
1619 or::
1620
1621 buffer_pattern=-12
1622
1623 or::
1624
1625 buffer_pattern=0xdeadface
1626
1627 Also you can combine everything together in any order::
1628
a1554f65 1629 buffer_pattern=0xdeadface"abcd"-12'filename'
f80dba8d
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1630
1631.. option:: dedupe_percentage=int
1632
1633 If set, fio will generate this percentage of identical buffers when
1634 writing. These buffers will be naturally dedupable. The contents of the
1635 buffers depend on what other buffer compression settings have been set. It's
1636 possible to have the individual buffers either fully compressible, or not at
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1637 all -- this option only controls the distribution of unique buffers. Setting
1638 this option will also enable :option:`refill_buffers` to prevent every buffer
1639 being identical.
f80dba8d
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1640
1641.. option:: invalidate=bool
1642
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1643 Invalidate the buffer/page cache parts of the files to be used prior to
1644 starting I/O if the platform and file type support it. Defaults to true.
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1645 This will be ignored if :option:`pre_read` is also specified for the
1646 same job.
f80dba8d
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1647
1648.. option:: sync=bool
1649
1650 Use synchronous I/O for buffered writes. For the majority of I/O engines,
1651 this means using O_SYNC. Default: false.
1652
1653.. option:: iomem=str, mem=str
1654
1655 Fio can use various types of memory as the I/O unit buffer. The allowed
1656 values are:
1657
1658 **malloc**
1659 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1660 type.
1661
1662 **shm**
1663 Use shared memory as the buffers. Allocated through
1664 :manpage:`shmget(2)`.
1665
1666 **shmhuge**
1667 Same as shm, but use huge pages as backing.
1668
1669 **mmap**
22413915 1670 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
f80dba8d
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1671 be file backed if a filename is given after the option. The format
1672 is `mem=mmap:/path/to/file`.
1673
1674 **mmaphuge**
1675 Use a memory mapped huge file as the buffer backing. Append filename
1676 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1677
1678 **mmapshared**
1679 Same as mmap, but use a MMAP_SHARED mapping.
1680
03553853
YR
1681 **cudamalloc**
1682 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
f50fbdda 1683 The :option:`ioengine` must be `rdma`.
03553853 1684
f80dba8d
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1685 The area allocated is a function of the maximum allowed bs size for the job,
1686 multiplied by the I/O depth given. Note that for **shmhuge** and
1687 **mmaphuge** to work, the system must have free huge pages allocated. This
1688 can normally be checked and set by reading/writing
1689 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1690 is 4MiB in size. So to calculate the number of huge pages you need for a
1691 given job file, add up the I/O depth of all jobs (normally one unless
1692 :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
1693 that number by the huge page size. You can see the size of the huge pages in
1694 :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
1695 number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
1696 see :option:`hugepage-size`.
1697
1698 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1699 should point there. So if it's mounted in :file:`/huge`, you would use
1700 `mem=mmaphuge:/huge/somefile`.
1701
f50fbdda 1702.. option:: iomem_align=int, mem_align=int
f80dba8d
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1703
1704 This indicates the memory alignment of the I/O memory buffers. Note that
1705 the given alignment is applied to the first I/O unit buffer, if using
1706 :option:`iodepth` the alignment of the following buffers are given by the
1707 :option:`bs` used. In other words, if using a :option:`bs` that is a
1708 multiple of the page sized in the system, all buffers will be aligned to
1709 this value. If using a :option:`bs` that is not page aligned, the alignment
1710 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1711 :option:`bs` used.
1712
1713.. option:: hugepage-size=int
1714
1715 Defines the size of a huge page. Must at least be equal to the system
1716 setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
1717 always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
1718 preferred way to set this to avoid setting a non-pow-2 bad value.
1719
1720.. option:: lockmem=int
1721
1722 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1723 simulate a smaller amount of memory. The amount specified is per worker.
1724
1725
1726I/O size
1727~~~~~~~~
1728
1729.. option:: size=int
1730
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1731 The total size of file I/O for each thread of this job. Fio will run until
1732 this many bytes has been transferred, unless runtime is limited by other options
1733 (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
1734 Fio will divide this size between the available files determined by options
1735 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1736 specified by the job. If the result of division happens to be 0, the size is
c4aa2d08 1737 set to the physical size of the given files or devices if they exist.
79591fa9 1738 If this option is not specified, fio will use the full size of the given
f80dba8d
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1739 files or devices. If the files do not exist, size must be given. It is also
1740 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1741 given, fio will use 20% of the full size of the given files or devices.
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1742 Can be combined with :option:`offset` to constrain the start and end range
1743 that I/O will be done within.
f80dba8d
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1744
1745.. option:: io_size=int, io_limit=int
1746
1747 Normally fio operates within the region set by :option:`size`, which means
1748 that the :option:`size` option sets both the region and size of I/O to be
1749 performed. Sometimes that is not what you want. With this option, it is
1750 possible to define just the amount of I/O that fio should do. For instance,
1751 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1752 will perform I/O within the first 20GiB but exit when 5GiB have been
1753 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1754 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1755 the 0..20GiB region.
1756
7fdd97ca 1757.. option:: filesize=irange(int)
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1758
1759 Individual file sizes. May be a range, in which case fio will select sizes
1760 for files at random within the given range and limited to :option:`size` in
1761 total (if that is given). If not given, each created file is the same size.
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1762 This option overrides :option:`size` in terms of file size, which means
1763 this value is used as a fixed size or possible range of each file.
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1764
1765.. option:: file_append=bool
1766
1767 Perform I/O after the end of the file. Normally fio will operate within the
1768 size of a file. If this option is set, then fio will append to the file
1769 instead. This has identical behavior to setting :option:`offset` to the size
1770 of a file. This option is ignored on non-regular files.
1771
1772.. option:: fill_device=bool, fill_fs=bool
1773
1774 Sets size to something really large and waits for ENOSPC (no space left on
1775 device) as the terminating condition. Only makes sense with sequential
1776 write. For a read workload, the mount point will be filled first then I/O
1777 started on the result. This option doesn't make sense if operating on a raw
1778 device node, since the size of that is already known by the file system.
1779 Additionally, writing beyond end-of-device will not return ENOSPC there.
1780
1781
1782I/O engine
1783~~~~~~~~~~
1784
1785.. option:: ioengine=str
1786
1787 Defines how the job issues I/O to the file. The following types are defined:
1788
1789 **sync**
1790 Basic :manpage:`read(2)` or :manpage:`write(2)`
1791 I/O. :manpage:`lseek(2)` is used to position the I/O location.
54227e6b 1792 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
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1793
1794 **psync**
1795 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1796 all supported operating systems except for Windows.
1797
1798 **vsync**
1799 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
c60ebc45 1800 queuing by coalescing adjacent I/Os into a single submission.
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1801
1802 **pvsync**
1803 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1804
1805 **pvsync2**
1806 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1807
1808 **libaio**
1809 Linux native asynchronous I/O. Note that Linux may only support
22413915 1810 queued behavior with non-buffered I/O (set ``direct=1`` or
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1811 ``buffered=0``).
1812 This engine defines engine specific options.
1813
1814 **posixaio**
1815 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
1816 :manpage:`aio_write(3)`.
1817
1818 **solarisaio**
1819 Solaris native asynchronous I/O.
1820
1821 **windowsaio**
1822 Windows native asynchronous I/O. Default on Windows.
1823
1824 **mmap**
1825 File is memory mapped with :manpage:`mmap(2)` and data copied
1826 to/from using :manpage:`memcpy(3)`.
1827
1828 **splice**
1829 :manpage:`splice(2)` is used to transfer the data and
1830 :manpage:`vmsplice(2)` to transfer data from user space to the
1831 kernel.
1832
1833 **sg**
1834 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
1835 ioctl, or if the target is an sg character device we use
1836 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
f50fbdda 1837 I/O. Requires :option:`filename` option to specify either block or
3740cfc8 1838 character devices. This engine supports trim operations.
52b81b7c 1839 The sg engine includes engine specific options.
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1840
1841 **null**
1842 Doesn't transfer any data, just pretends to. This is mainly used to
1843 exercise fio itself and for debugging/testing purposes.
1844
1845 **net**
1846 Transfer over the network to given ``host:port``. Depending on the
1847 :option:`protocol` used, the :option:`hostname`, :option:`port`,
1848 :option:`listen` and :option:`filename` options are used to specify
1849 what sort of connection to make, while the :option:`protocol` option
1850 determines which protocol will be used. This engine defines engine
1851 specific options.
1852
1853 **netsplice**
1854 Like **net**, but uses :manpage:`splice(2)` and
1855 :manpage:`vmsplice(2)` to map data and send/receive.
1856 This engine defines engine specific options.
1857
1858 **cpuio**
1859 Doesn't transfer any data, but burns CPU cycles according to the
1860 :option:`cpuload` and :option:`cpuchunks` options. Setting
9207a0cb 1861 :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
71aa48eb 1862 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
f50fbdda 1863 to get desired CPU usage, as the cpuload only loads a
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1864 single CPU at the desired rate. A job never finishes unless there is
1865 at least one non-cpuio job.
1866
1867 **guasi**
804c0839 1868 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall
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1869 Interface approach to async I/O. See
1870
1871 http://www.xmailserver.org/guasi-lib.html
1872
1873 for more info on GUASI.
1874
1875 **rdma**
1876 The RDMA I/O engine supports both RDMA memory semantics
1877 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
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1878 InfiniBand, RoCE and iWARP protocols. This engine defines engine
1879 specific options.
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1880
1881 **falloc**
1882 I/O engine that does regular fallocate to simulate data transfer as
1883 fio ioengine.
1884
1885 DDIR_READ
1886 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
1887
1888 DDIR_WRITE
1889 does fallocate(,mode = 0).
1890
1891 DDIR_TRIM
1892 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
1893
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1894 **ftruncate**
1895 I/O engine that sends :manpage:`ftruncate(2)` operations in response
1896 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
f50fbdda 1897 size to the current block offset. :option:`blocksize` is ignored.
761cd093 1898
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1899 **e4defrag**
1900 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
1901 defragment activity in request to DDIR_WRITE event.
1902
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1903 **rados**
1904 I/O engine supporting direct access to Ceph Reliable Autonomic
1905 Distributed Object Store (RADOS) via librados. This ioengine
1906 defines engine specific options.
1907
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1908 **rbd**
1909 I/O engine supporting direct access to Ceph Rados Block Devices
1910 (RBD) via librbd without the need to use the kernel rbd driver. This
1911 ioengine defines engine specific options.
1912
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1913 **http**
1914 I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to
1915 a WebDAV or S3 endpoint. This ioengine defines engine specific options.
1916
1917 This engine only supports direct IO of iodepth=1; you need to scale this
1918 via numjobs. blocksize defines the size of the objects to be created.
1919
1920 TRIM is translated to object deletion.
1921
f80dba8d 1922 **gfapi**
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1923 Using GlusterFS libgfapi sync interface to direct access to
1924 GlusterFS volumes without having to go through FUSE. This ioengine
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1925 defines engine specific options.
1926
1927 **gfapi_async**
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1928 Using GlusterFS libgfapi async interface to direct access to
1929 GlusterFS volumes without having to go through FUSE. This ioengine
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1930 defines engine specific options.
1931
1932 **libhdfs**
f50fbdda 1933 Read and write through Hadoop (HDFS). The :option:`filename` option
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1934 is used to specify host,port of the hdfs name-node to connect. This
1935 engine interprets offsets a little differently. In HDFS, files once
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1936 created cannot be modified so random writes are not possible. To
1937 imitate this the libhdfs engine expects a bunch of small files to be
1938 created over HDFS and will randomly pick a file from them
1939 based on the offset generated by fio backend (see the example
f80dba8d 1940 job file to create such files, use ``rw=write`` option). Please
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1941 note, it may be necessary to set environment variables to work
1942 with HDFS/libhdfs properly. Each job uses its own connection to
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1943 HDFS.
1944
1945 **mtd**
1946 Read, write and erase an MTD character device (e.g.,
1947 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
1948 underlying device type, the I/O may have to go in a certain pattern,
1949 e.g., on NAND, writing sequentially to erase blocks and discarding
c298ee71 1950 before overwriting. The `trimwrite` mode works well for this
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1951 constraint.
1952
1953 **pmemblk**
1954 Read and write using filesystem DAX to a file on a filesystem
363a5f65 1955 mounted with DAX on a persistent memory device through the PMDK
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1956 libpmemblk library.
1957
1958 **dev-dax**
1959 Read and write using device DAX to a persistent memory device (e.g.,
363a5f65 1960 /dev/dax0.0) through the PMDK libpmem library.
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1961
1962 **external**
1963 Prefix to specify loading an external I/O engine object file. Append
c60ebc45 1964 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
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1965 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
1966 absolute or relative. See :file:`engines/skeleton_external.c` for
1967 details of writing an external I/O engine.
f80dba8d 1968
1216cc5a 1969 **filecreate**
b71968b1 1970 Simply create the files and do no I/O to them. You still need to
1216cc5a 1971 set `filesize` so that all the accounting still occurs, but no
b71968b1 1972 actual I/O will be done other than creating the file.
f80dba8d 1973
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1974 **libpmem**
1975 Read and write using mmap I/O to a file on a filesystem
363a5f65 1976 mounted with DAX on a persistent memory device through the PMDK
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1977 libpmem library.
1978
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1979 **ime_psync**
1980 Synchronous read and write using DDN's Infinite Memory Engine (IME).
1981 This engine is very basic and issues calls to IME whenever an IO is
1982 queued.
1983
1984 **ime_psyncv**
1985 Synchronous read and write using DDN's Infinite Memory Engine (IME).
1986 This engine uses iovecs and will try to stack as much IOs as possible
1987 (if the IOs are "contiguous" and the IO depth is not exceeded)
1988 before issuing a call to IME.
1989
1990 **ime_aio**
1991 Asynchronous read and write using DDN's Infinite Memory Engine (IME).
1992 This engine will try to stack as much IOs as possible by creating
1993 requests for IME. FIO will then decide when to commit these requests.
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1994 **libiscsi**
1995 Read and write iscsi lun with libiscsi.
a40e7a59 1996
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1997I/O engine specific parameters
1998~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1999
2000In addition, there are some parameters which are only valid when a specific
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2001:option:`ioengine` is in use. These are used identically to normal parameters,
2002with the caveat that when used on the command line, they must come after the
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2003:option:`ioengine` that defines them is selected.
2004
2005.. option:: userspace_reap : [libaio]
2006
2007 Normally, with the libaio engine in use, fio will use the
2008 :manpage:`io_getevents(2)` system call to reap newly returned events. With
2009 this flag turned on, the AIO ring will be read directly from user-space to
2010 reap events. The reaping mode is only enabled when polling for a minimum of
c60ebc45 2011 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
f80dba8d 2012
9d25d068 2013.. option:: hipri : [pvsync2]
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2014
2015 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
2016 than normal.
2017
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2018.. option:: hipri_percentage : [pvsync2]
2019
f50fbdda 2020 When hipri is set this determines the probability of a pvsync2 I/O being high
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2021 priority. The default is 100%.
2022
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2023.. option:: cpuload=int : [cpuio]
2024
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2025 Attempt to use the specified percentage of CPU cycles. This is a mandatory
2026 option when using cpuio I/O engine.
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2027
2028.. option:: cpuchunks=int : [cpuio]
2029
2030 Split the load into cycles of the given time. In microseconds.
2031
2032.. option:: exit_on_io_done=bool : [cpuio]
2033
2034 Detect when I/O threads are done, then exit.
2035
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2036.. option:: namenode=str : [libhdfs]
2037
22413915 2038 The hostname or IP address of a HDFS cluster namenode to contact.
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2039
2040.. option:: port=int
2041
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2042 [libhdfs]
2043
2044 The listening port of the HFDS cluster namenode.
2045
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2046 [netsplice], [net]
2047
2048 The TCP or UDP port to bind to or connect to. If this is used with
2049 :option:`numjobs` to spawn multiple instances of the same job type, then
2050 this will be the starting port number since fio will use a range of
2051 ports.
2052
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2053 [rdma]
2054
2055 The port to use for RDMA-CM communication. This should be the same value
2056 on the client and the server side.
2057
2058.. option:: hostname=str : [netsplice] [net] [rdma]
f80dba8d 2059
609ac152
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2060 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
2061 is a TCP listener or UDP reader, the hostname is not used and must be omitted
f50fbdda 2062 unless it is a valid UDP multicast address.
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2063
2064.. option:: interface=str : [netsplice] [net]
2065
2066 The IP address of the network interface used to send or receive UDP
2067 multicast.
2068
2069.. option:: ttl=int : [netsplice] [net]
2070
2071 Time-to-live value for outgoing UDP multicast packets. Default: 1.
2072
2073.. option:: nodelay=bool : [netsplice] [net]
2074
2075 Set TCP_NODELAY on TCP connections.
2076
f50fbdda 2077.. option:: protocol=str, proto=str : [netsplice] [net]
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2078
2079 The network protocol to use. Accepted values are:
2080
2081 **tcp**
2082 Transmission control protocol.
2083 **tcpv6**
2084 Transmission control protocol V6.
2085 **udp**
2086 User datagram protocol.
2087 **udpv6**
2088 User datagram protocol V6.
2089 **unix**
2090 UNIX domain socket.
2091
2092 When the protocol is TCP or UDP, the port must also be given, as well as the
2093 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
f50fbdda 2094 normal :option:`filename` option should be used and the port is invalid.
f80dba8d 2095
e9184ec1 2096.. option:: listen : [netsplice] [net]
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2097
2098 For TCP network connections, tell fio to listen for incoming connections
2099 rather than initiating an outgoing connection. The :option:`hostname` must
2100 be omitted if this option is used.
2101
e9184ec1 2102.. option:: pingpong : [netsplice] [net]
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2103
2104 Normally a network writer will just continue writing data, and a network
2105 reader will just consume packages. If ``pingpong=1`` is set, a writer will
2106 send its normal payload to the reader, then wait for the reader to send the
2107 same payload back. This allows fio to measure network latencies. The
2108 submission and completion latencies then measure local time spent sending or
2109 receiving, and the completion latency measures how long it took for the
2110 other end to receive and send back. For UDP multicast traffic
2111 ``pingpong=1`` should only be set for a single reader when multiple readers
2112 are listening to the same address.
2113
e9184ec1 2114.. option:: window_size : [netsplice] [net]
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2115
2116 Set the desired socket buffer size for the connection.
2117
e9184ec1 2118.. option:: mss : [netsplice] [net]
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2119
2120 Set the TCP maximum segment size (TCP_MAXSEG).
2121
2122.. option:: donorname=str : [e4defrag]
2123
730bd7d9 2124 File will be used as a block donor (swap extents between files).
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2125
2126.. option:: inplace=int : [e4defrag]
2127
2128 Configure donor file blocks allocation strategy:
2129
2130 **0**
2131 Default. Preallocate donor's file on init.
2132 **1**
2b455dbf 2133 Allocate space immediately inside defragment event, and free right
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2134 after event.
2135
f3f96717 2136.. option:: clustername=str : [rbd,rados]
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2137
2138 Specifies the name of the Ceph cluster.
2139
2140.. option:: rbdname=str : [rbd]
2141
2142 Specifies the name of the RBD.
2143
f3f96717 2144.. option:: pool=str : [rbd,rados]
f80dba8d 2145
f3f96717 2146 Specifies the name of the Ceph pool containing RBD or RADOS data.
f80dba8d 2147
f3f96717 2148.. option:: clientname=str : [rbd,rados]
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2149
2150 Specifies the username (without the 'client.' prefix) used to access the
2151 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2152 the full *type.id* string. If no type. prefix is given, fio will add
2153 'client.' by default.
2154
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2155.. option:: busy_poll=bool : [rbd,rados]
2156
2157 Poll store instead of waiting for completion. Usually this provides better
2158 throughput at cost of higher(up to 100%) CPU utilization.
2159
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2160.. option:: skip_bad=bool : [mtd]
2161
2162 Skip operations against known bad blocks.
2163
2164.. option:: hdfsdirectory : [libhdfs]
2165
2166 libhdfs will create chunk in this HDFS directory.
2167
2168.. option:: chunk_size : [libhdfs]
2169
2b455dbf 2170 The size of the chunk to use for each file.
f80dba8d 2171
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2172.. option:: verb=str : [rdma]
2173
2174 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2175 values are write, read, send and recv. These correspond to the equivalent
2176 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2177 specified on the client side of the connection. See the examples folder.
2178
2179.. option:: bindname=str : [rdma]
2180
2181 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2182 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2183 will be passed into the rdma_bind_addr() function and on the client site it
2184 will be used in the rdma_resolve_add() function. This can be useful when
2185 multiple paths exist between the client and the server or in certain loopback
2186 configurations.
f80dba8d 2187
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2188.. option:: readfua=bool : [sg]
2189
2190 With readfua option set to 1, read operations include
2191 the force unit access (fua) flag. Default is 0.
2192
2193.. option:: writefua=bool : [sg]
2194
2195 With writefua option set to 1, write operations include
2196 the force unit access (fua) flag. Default is 0.
2197
2c3a9150 2198.. option:: sg_write_mode=str : [sg]
3740cfc8 2199
2c3a9150
VF
2200 Specify the type of write commands to issue. This option can take three values:
2201
2202 **write**
2203 This is the default where write opcodes are issued as usual.
2204 **verify**
2205 Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This
2206 directs the device to carry out a medium verification with no data
2207 comparison. The writefua option is ignored with this selection.
2208 **same**
2209 Issue WRITE SAME commands. This transfers a single block to the device
2210 and writes this same block of data to a contiguous sequence of LBAs
2211 beginning at the specified offset. fio's block size parameter specifies
2212 the amount of data written with each command. However, the amount of data
2213 actually transferred to the device is equal to the device's block
2214 (sector) size. For a device with 512 byte sectors, blocksize=8k will
2215 write 16 sectors with each command. fio will still generate 8k of data
2216 for each command but only the first 512 bytes will be used and
2217 transferred to the device. The writefua option is ignored with this
2218 selection.
52b81b7c 2219
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2220.. option:: http_host=str : [http]
2221
2222 Hostname to connect to. For S3, this could be the bucket hostname.
2223 Default is **localhost**
2224
2225.. option:: http_user=str : [http]
2226
2227 Username for HTTP authentication.
2228
2229.. option:: http_pass=str : [http]
2230
2231 Password for HTTP authentication.
2232
09fd2966 2233.. option:: https=str : [http]
c2f6a13d 2234
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2235 Enable HTTPS instead of http. *on* enables HTTPS; *insecure*
2236 will enable HTTPS, but disable SSL peer verification (use with
2237 caution!). Default is **off**
c2f6a13d 2238
09fd2966 2239.. option:: http_mode=str : [http]
c2f6a13d 2240
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2241 Which HTTP access mode to use: *webdav*, *swift*, or *s3*.
2242 Default is **webdav**
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2243
2244.. option:: http_s3_region=str : [http]
2245
2246 The S3 region/zone string.
2247 Default is **us-east-1**
2248
2249.. option:: http_s3_key=str : [http]
2250
2251 The S3 secret key.
2252
2253.. option:: http_s3_keyid=str : [http]
2254
2255 The S3 key/access id.
2256
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2257.. option:: http_swift_auth_token=str : [http]
2258
2259 The Swift auth token. See the example configuration file on how
2260 to retrieve this.
2261
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2262.. option:: http_verbose=int : [http]
2263
2264 Enable verbose requests from libcurl. Useful for debugging. 1
2265 turns on verbose logging from libcurl, 2 additionally enables
2266 HTTP IO tracing. Default is **0**
2267
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2268I/O depth
2269~~~~~~~~~
2270
2271.. option:: iodepth=int
2272
2273 Number of I/O units to keep in flight against the file. Note that
2274 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
c60ebc45 2275 for small degrees when :option:`verify_async` is in use). Even async
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2276 engines may impose OS restrictions causing the desired depth not to be
2277 achieved. This may happen on Linux when using libaio and not setting
9207a0cb 2278 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
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2279 eye on the I/O depth distribution in the fio output to verify that the
2280 achieved depth is as expected. Default: 1.
2281
2282.. option:: iodepth_batch_submit=int, iodepth_batch=int
2283
2284 This defines how many pieces of I/O to submit at once. It defaults to 1
2285 which means that we submit each I/O as soon as it is available, but can be
2286 raised to submit bigger batches of I/O at the time. If it is set to 0 the
2287 :option:`iodepth` value will be used.
2288
2289.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
2290
2291 This defines how many pieces of I/O to retrieve at once. It defaults to 1
2292 which means that we'll ask for a minimum of 1 I/O in the retrieval process
2293 from the kernel. The I/O retrieval will go on until we hit the limit set by
2294 :option:`iodepth_low`. If this variable is set to 0, then fio will always
2295 check for completed events before queuing more I/O. This helps reduce I/O
2296 latency, at the cost of more retrieval system calls.
2297
2298.. option:: iodepth_batch_complete_max=int
2299
2300 This defines maximum pieces of I/O to retrieve at once. This variable should
9207a0cb 2301 be used along with :option:`iodepth_batch_complete_min`\=int variable,
f80dba8d 2302 specifying the range of min and max amount of I/O which should be
730bd7d9 2303 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
f80dba8d
MT
2304 value.
2305
2306 Example #1::
2307
2308 iodepth_batch_complete_min=1
2309 iodepth_batch_complete_max=<iodepth>
2310
2311 which means that we will retrieve at least 1 I/O and up to the whole
2312 submitted queue depth. If none of I/O has been completed yet, we will wait.
2313
2314 Example #2::
2315
2316 iodepth_batch_complete_min=0
2317 iodepth_batch_complete_max=<iodepth>
2318
2319 which means that we can retrieve up to the whole submitted queue depth, but
2320 if none of I/O has been completed yet, we will NOT wait and immediately exit
2321 the system call. In this example we simply do polling.
2322
2323.. option:: iodepth_low=int
2324
2325 The low water mark indicating when to start filling the queue
2326 again. Defaults to the same as :option:`iodepth`, meaning that fio will
2327 attempt to keep the queue full at all times. If :option:`iodepth` is set to
c60ebc45 2328 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
f80dba8d
MT
2329 16 requests, it will let the depth drain down to 4 before starting to fill
2330 it again.
2331
997b5680
SW
2332.. option:: serialize_overlap=bool
2333
2334 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
2335 When two or more I/Os are submitted simultaneously, there is no guarantee that
2336 the I/Os will be processed or completed in the submitted order. Further, if
2337 two or more of those I/Os are writes, any overlapping region between them can
2338 become indeterminate/undefined on certain storage. These issues can cause
2339 verification to fail erratically when at least one of the racing I/Os is
2340 changing data and the overlapping region has a non-zero size. Setting
2341 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
2342 serializing in-flight I/Os that have a non-zero overlap. Note that setting
ee21ebee 2343 this option can reduce both performance and the :option:`iodepth` achieved.
3d6a6f04
VF
2344
2345 This option only applies to I/Os issued for a single job except when it is
2346 enabled along with :option:`io_submit_mode`=offload. In offload mode, fio
2347 will check for overlap among all I/Os submitted by offload jobs with :option:`serialize_overlap`
307f2246 2348 enabled.
3d6a6f04
VF
2349
2350 Default: false.
997b5680 2351
f80dba8d
MT
2352.. option:: io_submit_mode=str
2353
2354 This option controls how fio submits the I/O to the I/O engine. The default
2355 is `inline`, which means that the fio job threads submit and reap I/O
2356 directly. If set to `offload`, the job threads will offload I/O submission
2357 to a dedicated pool of I/O threads. This requires some coordination and thus
2358 has a bit of extra overhead, especially for lower queue depth I/O where it
2359 can increase latencies. The benefit is that fio can manage submission rates
2360 independently of the device completion rates. This avoids skewed latency
730bd7d9 2361 reporting if I/O gets backed up on the device side (the coordinated omission
f80dba8d
MT
2362 problem).
2363
2364
2365I/O rate
2366~~~~~~~~
2367
a881438b 2368.. option:: thinktime=time
f80dba8d 2369
f75ede1d
SW
2370 Stall the job for the specified period of time after an I/O has completed before issuing the
2371 next. May be used to simulate processing being done by an application.
947e0fe0 2372 When the unit is omitted, the value is interpreted in microseconds. See
f80dba8d
MT
2373 :option:`thinktime_blocks` and :option:`thinktime_spin`.
2374
a881438b 2375.. option:: thinktime_spin=time
f80dba8d
MT
2376
2377 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
2378 something with the data received, before falling back to sleeping for the
f75ede1d 2379 rest of the period specified by :option:`thinktime`. When the unit is
947e0fe0 2380 omitted, the value is interpreted in microseconds.
f80dba8d
MT
2381
2382.. option:: thinktime_blocks=int
2383
2384 Only valid if :option:`thinktime` is set - control how many blocks to issue,
f50fbdda
TK
2385 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
2386 fio wait :option:`thinktime` usecs after every block. This effectively makes any
f80dba8d 2387 queue depth setting redundant, since no more than 1 I/O will be queued
f50fbdda 2388 before we have to complete it and do our :option:`thinktime`. In other words, this
f80dba8d 2389 setting effectively caps the queue depth if the latter is larger.
71bfa161 2390
f80dba8d 2391.. option:: rate=int[,int][,int]
71bfa161 2392
f80dba8d
MT
2393 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
2394 suffix rules apply. Comma-separated values may be specified for reads,
2395 writes, and trims as described in :option:`blocksize`.
71bfa161 2396
b25b3464
SW
2397 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
2398 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
2399 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
2400 latter will only limit reads.
2401
f80dba8d 2402.. option:: rate_min=int[,int][,int]
71bfa161 2403
f80dba8d
MT
2404 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
2405 to meet this requirement will cause the job to exit. Comma-separated values
2406 may be specified for reads, writes, and trims as described in
2407 :option:`blocksize`.
71bfa161 2408
f80dba8d 2409.. option:: rate_iops=int[,int][,int]
71bfa161 2410
f80dba8d
MT
2411 Cap the bandwidth to this number of IOPS. Basically the same as
2412 :option:`rate`, just specified independently of bandwidth. If the job is
2413 given a block size range instead of a fixed value, the smallest block size
2414 is used as the metric. Comma-separated values may be specified for reads,
2415 writes, and trims as described in :option:`blocksize`.
71bfa161 2416
f80dba8d 2417.. option:: rate_iops_min=int[,int][,int]
71bfa161 2418
f80dba8d
MT
2419 If fio doesn't meet this rate of I/O, it will cause the job to exit.
2420 Comma-separated values may be specified for reads, writes, and trims as
2421 described in :option:`blocksize`.
71bfa161 2422
f80dba8d 2423.. option:: rate_process=str
66c098b8 2424
f80dba8d
MT
2425 This option controls how fio manages rated I/O submissions. The default is
2426 `linear`, which submits I/O in a linear fashion with fixed delays between
c60ebc45 2427 I/Os that gets adjusted based on I/O completion rates. If this is set to
f80dba8d
MT
2428 `poisson`, fio will submit I/O based on a more real world random request
2429 flow, known as the Poisson process
2430 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
2431 10^6 / IOPS for the given workload.
71bfa161 2432
1a9bf814
JA
2433.. option:: rate_ignore_thinktime=bool
2434
2435 By default, fio will attempt to catch up to the specified rate setting,
2436 if any kind of thinktime setting was used. If this option is set, then
2437 fio will ignore the thinktime and continue doing IO at the specified
2438 rate, instead of entering a catch-up mode after thinktime is done.
2439
71bfa161 2440
f80dba8d
MT
2441I/O latency
2442~~~~~~~~~~~
71bfa161 2443
a881438b 2444.. option:: latency_target=time
71bfa161 2445
f80dba8d 2446 If set, fio will attempt to find the max performance point that the given
f75ede1d 2447 workload will run at while maintaining a latency below this target. When
947e0fe0 2448 the unit is omitted, the value is interpreted in microseconds. See
f75ede1d 2449 :option:`latency_window` and :option:`latency_percentile`.
71bfa161 2450
a881438b 2451.. option:: latency_window=time
71bfa161 2452
f80dba8d 2453 Used with :option:`latency_target` to specify the sample window that the job
f75ede1d 2454 is run at varying queue depths to test the performance. When the unit is
947e0fe0 2455 omitted, the value is interpreted in microseconds.
b4692828 2456
f80dba8d 2457.. option:: latency_percentile=float
71bfa161 2458
c60ebc45 2459 The percentage of I/Os that must fall within the criteria specified by
f80dba8d 2460 :option:`latency_target` and :option:`latency_window`. If not set, this
c60ebc45 2461 defaults to 100.0, meaning that all I/Os must be equal or below to the value
f80dba8d 2462 set by :option:`latency_target`.
71bfa161 2463
a881438b 2464.. option:: max_latency=time
71bfa161 2465
f75ede1d 2466 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
947e0fe0 2467 maximum latency. When the unit is omitted, the value is interpreted in
f75ede1d 2468 microseconds.
71bfa161 2469
f80dba8d 2470.. option:: rate_cycle=int
71bfa161 2471
f80dba8d 2472 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
a47b697c 2473 of milliseconds. Defaults to 1000.
71bfa161 2474
71bfa161 2475
f80dba8d
MT
2476I/O replay
2477~~~~~~~~~~
71bfa161 2478
f80dba8d 2479.. option:: write_iolog=str
c2b1e753 2480
f80dba8d
MT
2481 Write the issued I/O patterns to the specified file. See
2482 :option:`read_iolog`. Specify a separate file for each job, otherwise the
2483 iologs will be interspersed and the file may be corrupt.
c2b1e753 2484
f80dba8d 2485.. option:: read_iolog=str
71bfa161 2486
22413915 2487 Open an iolog with the specified filename and replay the I/O patterns it
f80dba8d
MT
2488 contains. This can be used to store a workload and replay it sometime
2489 later. The iolog given may also be a blktrace binary file, which allows fio
2490 to replay a workload captured by :command:`blktrace`. See
2491 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
2492 replay, the file needs to be turned into a blkparse binary data file first
2493 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
78439a18
JA
2494 You can specify a number of files by separating the names with a ':'
2495 character. See the :option:`filename` option for information on how to
2496 escape ':' and '\' characters within the file names. These files will
2497 be sequentially assigned to job clones created by :option:`numjobs`.
71bfa161 2498
77be374d
AK
2499.. option:: read_iolog_chunked=bool
2500
2501 Determines how iolog is read. If false(default) entire :option:`read_iolog`
2502 will be read at once. If selected true, input from iolog will be read
2503 gradually. Useful when iolog is very large, or it is generated.
2504
b9921d1a
DZ
2505.. option:: merge_blktrace_file=str
2506
2507 When specified, rather than replaying the logs passed to :option:`read_iolog`,
2508 the logs go through a merge phase which aggregates them into a single
2509 blktrace. The resulting file is then passed on as the :option:`read_iolog`
2510 parameter. The intention here is to make the order of events consistent.
2511 This limits the influence of the scheduler compared to replaying multiple
2512 blktraces via concurrent jobs.
2513
87a48ada
DZ
2514.. option:: merge_blktrace_scalars=float_list
2515
2516 This is a percentage based option that is index paired with the list of
2517 files passed to :option:`read_iolog`. When merging is performed, scale
2518 the time of each event by the corresponding amount. For example,
2519 ``--merge_blktrace_scalars="50:100"`` runs the first trace in halftime
2520 and the second trace in realtime. This knob is separately tunable from
2521 :option:`replay_time_scale` which scales the trace during runtime and
2522 does not change the output of the merge unlike this option.
2523
55bfd8c8
DZ
2524.. option:: merge_blktrace_iters=float_list
2525
2526 This is a whole number option that is index paired with the list of files
2527 passed to :option:`read_iolog`. When merging is performed, run each trace
2528 for the specified number of iterations. For example,
2529 ``--merge_blktrace_iters="2:1"`` runs the first trace for two iterations
2530 and the second trace for one iteration.
2531
589e88b7 2532.. option:: replay_no_stall=bool
71bfa161 2533
f80dba8d 2534 When replaying I/O with :option:`read_iolog` the default behavior is to
22413915 2535 attempt to respect the timestamps within the log and replay them with the
f80dba8d
MT
2536 appropriate delay between IOPS. By setting this variable fio will not
2537 respect the timestamps and attempt to replay them as fast as possible while
2538 still respecting ordering. The result is the same I/O pattern to a given
2539 device, but different timings.
71bfa161 2540
6dd7fa77
JA
2541.. option:: replay_time_scale=int
2542
2543 When replaying I/O with :option:`read_iolog`, fio will honor the
2544 original timing in the trace. With this option, it's possible to scale
2545 the time. It's a percentage option, if set to 50 it means run at 50%
2546 the original IO rate in the trace. If set to 200, run at twice the
2547 original IO rate. Defaults to 100.
2548
f80dba8d 2549.. option:: replay_redirect=str
b4692828 2550
f80dba8d
MT
2551 While replaying I/O patterns using :option:`read_iolog` the default behavior
2552 is to replay the IOPS onto the major/minor device that each IOP was recorded
2553 from. This is sometimes undesirable because on a different machine those
2554 major/minor numbers can map to a different device. Changing hardware on the
2555 same system can also result in a different major/minor mapping.
730bd7d9 2556 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
f80dba8d 2557 device regardless of the device it was recorded
9207a0cb 2558 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
f80dba8d
MT
2559 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
2560 multiple devices will be replayed onto a single device, if the trace
2561 contains multiple devices. If you want multiple devices to be replayed
2562 concurrently to multiple redirected devices you must blkparse your trace
2563 into separate traces and replay them with independent fio invocations.
2564 Unfortunately this also breaks the strict time ordering between multiple
2565 device accesses.
71bfa161 2566
f80dba8d 2567.. option:: replay_align=int
74929ac2 2568
350a535d
DZ
2569 Force alignment of the byte offsets in a trace to this value. The value
2570 must be a power of 2.
3c54bc46 2571
f80dba8d 2572.. option:: replay_scale=int
3c54bc46 2573
350a535d
DZ
2574 Scale byte offsets down by this factor when replaying traces. Should most
2575 likely use :option:`replay_align` as well.
3c54bc46 2576
38f68906
JA
2577.. option:: replay_skip=str
2578
2579 Sometimes it's useful to skip certain IO types in a replay trace.
2580 This could be, for instance, eliminating the writes in the trace.
2581 Or not replaying the trims/discards, if you are redirecting to
2582 a device that doesn't support them. This option takes a comma
2583 separated list of read, write, trim, sync.
2584
3c54bc46 2585
f80dba8d
MT
2586Threads, processes and job synchronization
2587~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3c54bc46 2588
f80dba8d 2589.. option:: thread
3c54bc46 2590
730bd7d9
SW
2591 Fio defaults to creating jobs by using fork, however if this option is
2592 given, fio will create jobs by using POSIX Threads' function
2593 :manpage:`pthread_create(3)` to create threads instead.
71bfa161 2594
f80dba8d 2595.. option:: wait_for=str
74929ac2 2596
730bd7d9
SW
2597 If set, the current job won't be started until all workers of the specified
2598 waitee job are done.
74929ac2 2599
f80dba8d
MT
2600 ``wait_for`` operates on the job name basis, so there are a few
2601 limitations. First, the waitee must be defined prior to the waiter job
2602 (meaning no forward references). Second, if a job is being referenced as a
2603 waitee, it must have a unique name (no duplicate waitees).
74929ac2 2604
f80dba8d 2605.. option:: nice=int
892a6ffc 2606
f80dba8d 2607 Run the job with the given nice value. See man :manpage:`nice(2)`.
892a6ffc 2608
f80dba8d
MT
2609 On Windows, values less than -15 set the process class to "High"; -1 through
2610 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
2611 priority class.
74929ac2 2612
f80dba8d 2613.. option:: prio=int
71bfa161 2614
f80dba8d
MT
2615 Set the I/O priority value of this job. Linux limits us to a positive value
2616 between 0 and 7, with 0 being the highest. See man
2617 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
2618 systems since meaning of priority may differ.
71bfa161 2619
f80dba8d 2620.. option:: prioclass=int
d59aa780 2621
f80dba8d 2622 Set the I/O priority class. See man :manpage:`ionice(1)`.
d59aa780 2623
f80dba8d 2624.. option:: cpus_allowed=str
6d500c2e 2625
730bd7d9 2626 Controls the same options as :option:`cpumask`, but accepts a textual
b570e037
SW
2627 specification of the permitted CPUs instead and CPUs are indexed from 0. So
2628 to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
2629 allows a range of CPUs to be specified -- say you wanted a binding to CPUs
2630 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
2631
2632 On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
2633 processor group will be used and affinity settings are inherited from the
2634 system. An fio build configured to target Windows 7 makes options that set
2635 CPUs processor group aware and values will set both the processor group
2636 and a CPU from within that group. For example, on a system where processor
2637 group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
2638 values between 0 and 39 will bind CPUs from processor group 0 and
2639 ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
2640 group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
2641 single ``cpus_allowed`` option must be from the same processor group. For
2642 Windows fio builds not built for Windows 7, CPUs will only be selected from
2643 (and be relative to) whatever processor group fio happens to be running in
2644 and CPUs from other processor groups cannot be used.
6d500c2e 2645
f80dba8d 2646.. option:: cpus_allowed_policy=str
6d500c2e 2647
f80dba8d 2648 Set the policy of how fio distributes the CPUs specified by
730bd7d9 2649 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
6d500c2e 2650
f80dba8d
MT
2651 **shared**
2652 All jobs will share the CPU set specified.
2653 **split**
2654 Each job will get a unique CPU from the CPU set.
6d500c2e 2655
22413915 2656 **shared** is the default behavior, if the option isn't specified. If
f80dba8d
MT
2657 **split** is specified, then fio will will assign one cpu per job. If not
2658 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
2659 in the set.
6d500c2e 2660
b570e037
SW
2661.. option:: cpumask=int
2662
2663 Set the CPU affinity of this job. The parameter given is a bit mask of
2664 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
2665 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
2666 :manpage:`sched_setaffinity(2)`. This may not work on all supported
2667 operating systems or kernel versions. This option doesn't work well for a
2668 higher CPU count than what you can store in an integer mask, so it can only
2669 control cpus 1-32. For boxes with larger CPU counts, use
2670 :option:`cpus_allowed`.
2671
f80dba8d 2672.. option:: numa_cpu_nodes=str
6d500c2e 2673
f80dba8d
MT
2674 Set this job running on specified NUMA nodes' CPUs. The arguments allow
2675 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
ac8ca2af 2676 NUMA options support, fio must be built on a system with libnuma-dev(el)
f80dba8d 2677 installed.
61b9861d 2678
f80dba8d 2679.. option:: numa_mem_policy=str
61b9861d 2680
f80dba8d
MT
2681 Set this job's memory policy and corresponding NUMA nodes. Format of the
2682 arguments::
5c94b008 2683
f80dba8d 2684 <mode>[:<nodelist>]
ce35b1ec 2685
804c0839 2686 ``mode`` is one of the following memory policies: ``default``, ``prefer``,
730bd7d9
SW
2687 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
2688 policies, no node needs to be specified. For ``prefer``, only one node is
2689 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
2690 follows: a comma delimited list of numbers, A-B ranges, or `all`.
71bfa161 2691
f80dba8d 2692.. option:: cgroup=str
390b1537 2693
f80dba8d
MT
2694 Add job to this control group. If it doesn't exist, it will be created. The
2695 system must have a mounted cgroup blkio mount point for this to work. If
2696 your system doesn't have it mounted, you can do so with::
5af1c6f3 2697
f80dba8d 2698 # mount -t cgroup -o blkio none /cgroup
5af1c6f3 2699
f80dba8d 2700.. option:: cgroup_weight=int
5af1c6f3 2701
f80dba8d
MT
2702 Set the weight of the cgroup to this value. See the documentation that comes
2703 with the kernel, allowed values are in the range of 100..1000.
a086c257 2704
f80dba8d 2705.. option:: cgroup_nodelete=bool
8c07860d 2706
f80dba8d
MT
2707 Normally fio will delete the cgroups it has created after the job
2708 completion. To override this behavior and to leave cgroups around after the
2709 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
2710 to inspect various cgroup files after job completion. Default: false.
8c07860d 2711
f80dba8d 2712.. option:: flow_id=int
8c07860d 2713
f80dba8d
MT
2714 The ID of the flow. If not specified, it defaults to being a global
2715 flow. See :option:`flow`.
1907dbc6 2716
f80dba8d 2717.. option:: flow=int
71bfa161 2718
f80dba8d
MT
2719 Weight in token-based flow control. If this value is used, then there is a
2720 'flow counter' which is used to regulate the proportion of activity between
2721 two or more jobs. Fio attempts to keep this flow counter near zero. The
2722 ``flow`` parameter stands for how much should be added or subtracted to the
2723 flow counter on each iteration of the main I/O loop. That is, if one job has
2724 ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
2725 ratio in how much one runs vs the other.
71bfa161 2726
f80dba8d 2727.. option:: flow_watermark=int
a31041ea 2728
f80dba8d
MT
2729 The maximum value that the absolute value of the flow counter is allowed to
2730 reach before the job must wait for a lower value of the counter.
82407585 2731
f80dba8d 2732.. option:: flow_sleep=int
82407585 2733
f80dba8d
MT
2734 The period of time, in microseconds, to wait after the flow watermark has
2735 been exceeded before retrying operations.
82407585 2736
f80dba8d 2737.. option:: stonewall, wait_for_previous
82407585 2738
f80dba8d
MT
2739 Wait for preceding jobs in the job file to exit, before starting this
2740 one. Can be used to insert serialization points in the job file. A stone
2741 wall also implies starting a new reporting group, see
2742 :option:`group_reporting`.
2743
2744.. option:: exitall
2745
730bd7d9
SW
2746 By default, fio will continue running all other jobs when one job finishes
2747 but sometimes this is not the desired action. Setting ``exitall`` will
2748 instead make fio terminate all other jobs when one job finishes.
f80dba8d
MT
2749
2750.. option:: exec_prerun=str
2751
2752 Before running this job, issue the command specified through
2753 :manpage:`system(3)`. Output is redirected in a file called
2754 :file:`jobname.prerun.txt`.
2755
2756.. option:: exec_postrun=str
2757
2758 After the job completes, issue the command specified though
2759 :manpage:`system(3)`. Output is redirected in a file called
2760 :file:`jobname.postrun.txt`.
2761
2762.. option:: uid=int
2763
2764 Instead of running as the invoking user, set the user ID to this value
2765 before the thread/process does any work.
2766
2767.. option:: gid=int
2768
2769 Set group ID, see :option:`uid`.
2770
2771
2772Verification
2773~~~~~~~~~~~~
2774
2775.. option:: verify_only
2776
2777 Do not perform specified workload, only verify data still matches previous
2778 invocation of this workload. This option allows one to check data multiple
2779 times at a later date without overwriting it. This option makes sense only
2780 for workloads that write data, and does not support workloads with the
2781 :option:`time_based` option set.
2782
2783.. option:: do_verify=bool
2784
2785 Run the verify phase after a write phase. Only valid if :option:`verify` is
2786 set. Default: true.
2787
2788.. option:: verify=str
2789
2790 If writing to a file, fio can verify the file contents after each iteration
2791 of the job. Each verification method also implies verification of special
2792 header, which is written to the beginning of each block. This header also
2793 includes meta information, like offset of the block, block number, timestamp
2794 when block was written, etc. :option:`verify` can be combined with
2795 :option:`verify_pattern` option. The allowed values are:
2796
2797 **md5**
2798 Use an md5 sum of the data area and store it in the header of
2799 each block.
2800
2801 **crc64**
2802 Use an experimental crc64 sum of the data area and store it in the
2803 header of each block.
2804
2805 **crc32c**
a5896300
SW
2806 Use a crc32c sum of the data area and store it in the header of
2807 each block. This will automatically use hardware acceleration
2808 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
2809 fall back to software crc32c if none is found. Generally the
804c0839 2810 fastest checksum fio supports when hardware accelerated.
f80dba8d
MT
2811
2812 **crc32c-intel**
a5896300 2813 Synonym for crc32c.
f80dba8d
MT
2814
2815 **crc32**
2816 Use a crc32 sum of the data area and store it in the header of each
2817 block.
2818
2819 **crc16**
2820 Use a crc16 sum of the data area and store it in the header of each
2821 block.
2822
2823 **crc7**
2824 Use a crc7 sum of the data area and store it in the header of each
2825 block.
2826
2827 **xxhash**
2828 Use xxhash as the checksum function. Generally the fastest software
2829 checksum that fio supports.
2830
2831 **sha512**
2832 Use sha512 as the checksum function.
2833
2834 **sha256**
2835 Use sha256 as the checksum function.
2836
2837 **sha1**
2838 Use optimized sha1 as the checksum function.
82407585 2839
ae3a5acc
JA
2840 **sha3-224**
2841 Use optimized sha3-224 as the checksum function.
2842
2843 **sha3-256**
2844 Use optimized sha3-256 as the checksum function.
2845
2846 **sha3-384**
2847 Use optimized sha3-384 as the checksum function.
2848
2849 **sha3-512**
2850 Use optimized sha3-512 as the checksum function.
2851
f80dba8d
MT
2852 **meta**
2853 This option is deprecated, since now meta information is included in
2854 generic verification header and meta verification happens by
2855 default. For detailed information see the description of the
2856 :option:`verify` setting. This option is kept because of
2857 compatibility's sake with old configurations. Do not use it.
2858
2859 **pattern**
2860 Verify a strict pattern. Normally fio includes a header with some
2861 basic information and checksumming, but if this option is set, only
2862 the specific pattern set with :option:`verify_pattern` is verified.
2863
2864 **null**
2865 Only pretend to verify. Useful for testing internals with
9207a0cb 2866 :option:`ioengine`\=null, not for much else.
f80dba8d
MT
2867
2868 This option can be used for repeated burn-in tests of a system to make sure
2869 that the written data is also correctly read back. If the data direction
2870 given is a read or random read, fio will assume that it should verify a
2871 previously written file. If the data direction includes any form of write,
2872 the verify will be of the newly written data.
2873
47e6a6e5
SW
2874 To avoid false verification errors, do not use the norandommap option when
2875 verifying data with async I/O engines and I/O depths > 1. Or use the
2876 norandommap and the lfsr random generator together to avoid writing to the
2877 same offset with muliple outstanding I/Os.
2878
f80dba8d
MT
2879.. option:: verify_offset=int
2880
2881 Swap the verification header with data somewhere else in the block before
2882 writing. It is swapped back before verifying.
2883
2884.. option:: verify_interval=int
2885
2886 Write the verification header at a finer granularity than the
2887 :option:`blocksize`. It will be written for chunks the size of
2888 ``verify_interval``. :option:`blocksize` should divide this evenly.
2889
2890.. option:: verify_pattern=str
2891
2892 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
2893 filling with totally random bytes, but sometimes it's interesting to fill
2894 with a known pattern for I/O verification purposes. Depending on the width
730bd7d9 2895 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
f80dba8d
MT
2896 be either a decimal or a hex number). The ``verify_pattern`` if larger than
2897 a 32-bit quantity has to be a hex number that starts with either "0x" or
2898 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
2899 format, which means that for each block offset will be written and then
2900 verified back, e.g.::
61b9861d
RP
2901
2902 verify_pattern=%o
2903
f80dba8d
MT
2904 Or use combination of everything::
2905
61b9861d 2906 verify_pattern=0xff%o"abcd"-12
e28218f3 2907
f80dba8d
MT
2908.. option:: verify_fatal=bool
2909
2910 Normally fio will keep checking the entire contents before quitting on a
2911 block verification failure. If this option is set, fio will exit the job on
2912 the first observed failure. Default: false.
2913
2914.. option:: verify_dump=bool
2915
2916 If set, dump the contents of both the original data block and the data block
2917 we read off disk to files. This allows later analysis to inspect just what
2918 kind of data corruption occurred. Off by default.
2919
2920.. option:: verify_async=int
2921
2922 Fio will normally verify I/O inline from the submitting thread. This option
2923 takes an integer describing how many async offload threads to create for I/O
2924 verification instead, causing fio to offload the duty of verifying I/O
2925 contents to one or more separate threads. If using this offload option, even
2926 sync I/O engines can benefit from using an :option:`iodepth` setting higher
2927 than 1, as it allows them to have I/O in flight while verifies are running.
d7e6ea1c 2928 Defaults to 0 async threads, i.e. verification is not asynchronous.
f80dba8d
MT
2929
2930.. option:: verify_async_cpus=str
2931
2932 Tell fio to set the given CPU affinity on the async I/O verification
2933 threads. See :option:`cpus_allowed` for the format used.
2934
2935.. option:: verify_backlog=int
2936
2937 Fio will normally verify the written contents of a job that utilizes verify
2938 once that job has completed. In other words, everything is written then
2939 everything is read back and verified. You may want to verify continually
2940 instead for a variety of reasons. Fio stores the meta data associated with
2941 an I/O block in memory, so for large verify workloads, quite a bit of memory
2942 would be used up holding this meta data. If this option is enabled, fio will
2943 write only N blocks before verifying these blocks.
2944
2945.. option:: verify_backlog_batch=int
2946
2947 Control how many blocks fio will verify if :option:`verify_backlog` is
2948 set. If not set, will default to the value of :option:`verify_backlog`
2949 (meaning the entire queue is read back and verified). If
2950 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
2951 blocks will be verified, if ``verify_backlog_batch`` is larger than
2952 :option:`verify_backlog`, some blocks will be verified more than once.
2953
2954.. option:: verify_state_save=bool
2955
2956 When a job exits during the write phase of a verify workload, save its
2957 current state. This allows fio to replay up until that point, if the verify
2958 state is loaded for the verify read phase. The format of the filename is,
2959 roughly::
2960
f50fbdda 2961 <type>-<jobname>-<jobindex>-verify.state.
f80dba8d
MT
2962
2963 <type> is "local" for a local run, "sock" for a client/server socket
2964 connection, and "ip" (192.168.0.1, for instance) for a networked
d7e6ea1c 2965 client/server connection. Defaults to true.
f80dba8d
MT
2966
2967.. option:: verify_state_load=bool
2968
2969 If a verify termination trigger was used, fio stores the current write state
2970 of each thread. This can be used at verification time so that fio knows how
2971 far it should verify. Without this information, fio will run a full
a47b697c
SW
2972 verification pass, according to the settings in the job file used. Default
2973 false.
f80dba8d
MT
2974
2975.. option:: trim_percentage=int
2976
2977 Number of verify blocks to discard/trim.
2978
2979.. option:: trim_verify_zero=bool
2980
22413915 2981 Verify that trim/discarded blocks are returned as zeros.
f80dba8d
MT
2982
2983.. option:: trim_backlog=int
2984
5cfd1e9a 2985 Trim after this number of blocks are written.
f80dba8d
MT
2986
2987.. option:: trim_backlog_batch=int
2988
2989 Trim this number of I/O blocks.
2990
2991.. option:: experimental_verify=bool
2992
2993 Enable experimental verification.
2994
f80dba8d
MT
2995Steady state
2996~~~~~~~~~~~~
2997
2998.. option:: steadystate=str:float, ss=str:float
2999
3000 Define the criterion and limit for assessing steady state performance. The
3001 first parameter designates the criterion whereas the second parameter sets
3002 the threshold. When the criterion falls below the threshold for the
3003 specified duration, the job will stop. For example, `iops_slope:0.1%` will
3004 direct fio to terminate the job when the least squares regression slope
3005 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
3006 this will apply to all jobs in the group. Below is the list of available
3007 steady state assessment criteria. All assessments are carried out using only
3008 data from the rolling collection window. Threshold limits can be expressed
3009 as a fixed value or as a percentage of the mean in the collection window.
3010
1cb049d9
VF
3011 When using this feature, most jobs should include the :option:`time_based`
3012 and :option:`runtime` options or the :option:`loops` option so that fio does not
3013 stop running after it has covered the full size of the specified file(s) or device(s).
3014
f80dba8d
MT
3015 **iops**
3016 Collect IOPS data. Stop the job if all individual IOPS measurements
3017 are within the specified limit of the mean IOPS (e.g., ``iops:2``
3018 means that all individual IOPS values must be within 2 of the mean,
3019 whereas ``iops:0.2%`` means that all individual IOPS values must be
3020 within 0.2% of the mean IOPS to terminate the job).
3021
3022 **iops_slope**
3023 Collect IOPS data and calculate the least squares regression
3024 slope. Stop the job if the slope falls below the specified limit.
3025
3026 **bw**
3027 Collect bandwidth data. Stop the job if all individual bandwidth
3028 measurements are within the specified limit of the mean bandwidth.
3029
3030 **bw_slope**
3031 Collect bandwidth data and calculate the least squares regression
3032 slope. Stop the job if the slope falls below the specified limit.
3033
3034.. option:: steadystate_duration=time, ss_dur=time
3035
3036 A rolling window of this duration will be used to judge whether steady state
3037 has been reached. Data will be collected once per second. The default is 0
f75ede1d 3038 which disables steady state detection. When the unit is omitted, the
947e0fe0 3039 value is interpreted in seconds.
f80dba8d
MT
3040
3041.. option:: steadystate_ramp_time=time, ss_ramp=time
3042
3043 Allow the job to run for the specified duration before beginning data
3044 collection for checking the steady state job termination criterion. The
947e0fe0 3045 default is 0. When the unit is omitted, the value is interpreted in seconds.
f80dba8d
MT
3046
3047
3048Measurements and reporting
3049~~~~~~~~~~~~~~~~~~~~~~~~~~
3050
3051.. option:: per_job_logs=bool
3052
3053 If set, this generates bw/clat/iops log with per file private filenames. If
3054 not set, jobs with identical names will share the log filename. Default:
3055 true.
3056
3057.. option:: group_reporting
3058
3059 It may sometimes be interesting to display statistics for groups of jobs as
3060 a whole instead of for each individual job. This is especially true if
3061 :option:`numjobs` is used; looking at individual thread/process output
3062 quickly becomes unwieldy. To see the final report per-group instead of
3063 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
3064 same reporting group, unless if separated by a :option:`stonewall`, or by
3065 using :option:`new_group`.
3066
3067.. option:: new_group
3068
3069 Start a new reporting group. See: :option:`group_reporting`. If not given,
3070 all jobs in a file will be part of the same reporting group, unless
3071 separated by a :option:`stonewall`.
3072
589e88b7 3073.. option:: stats=bool
8243be59
JA
3074
3075 By default, fio collects and shows final output results for all jobs
3076 that run. If this option is set to 0, then fio will ignore it in
3077 the final stat output.
3078
f80dba8d
MT
3079.. option:: write_bw_log=str
3080
3081 If given, write a bandwidth log for this job. Can be used to store data of
074f0817 3082 the bandwidth of the jobs in their lifetime.
f80dba8d 3083
074f0817
SW
3084 If no str argument is given, the default filename of
3085 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
3086 will still append the type of log. So if one specifies::
3087
3088 write_bw_log=foo
f80dba8d 3089
074f0817
SW
3090 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
3091 of the job (`1..N`, where `N` is the number of jobs). If
3092 :option:`per_job_logs` is false, then the filename will not include the
3093 `.x` job index.
e3cedca7 3094
074f0817
SW
3095 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
3096 text files into nice graphs. See `Log File Formats`_ for how data is
3097 structured within the file.
3098
3099.. option:: write_lat_log=str
e3cedca7 3100
074f0817 3101 Same as :option:`write_bw_log`, except this option creates I/O
77b7e675
SW
3102 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
3103 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
074f0817
SW
3104 latency files instead. See :option:`write_bw_log` for details about
3105 the filename format and `Log File Formats`_ for how data is structured
3106 within the files.
be4ecfdf 3107
f80dba8d 3108.. option:: write_hist_log=str
06842027 3109
074f0817 3110 Same as :option:`write_bw_log` but writes an I/O completion latency
77b7e675 3111 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
074f0817
SW
3112 file will be empty unless :option:`log_hist_msec` has also been set.
3113 See :option:`write_bw_log` for details about the filename format and
3114 `Log File Formats`_ for how data is structured within the file.
06842027 3115
f80dba8d 3116.. option:: write_iops_log=str
06842027 3117
074f0817 3118 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
15417073
SW
3119 :file:`name_iops.x.log`) instead. Because fio defaults to individual
3120 I/O logging, the value entry in the IOPS log will be 1 unless windowed
3121 logging (see :option:`log_avg_msec`) has been enabled. See
3122 :option:`write_bw_log` for details about the filename format and `Log
3123 File Formats`_ for how data is structured within the file.
06842027 3124
f80dba8d 3125.. option:: log_avg_msec=int
06842027 3126
f80dba8d
MT
3127 By default, fio will log an entry in the iops, latency, or bw log for every
3128 I/O that completes. When writing to the disk log, that can quickly grow to a
3129 very large size. Setting this option makes fio average the each log entry
3130 over the specified period of time, reducing the resolution of the log. See
3131 :option:`log_max_value` as well. Defaults to 0, logging all entries.
6fc82095 3132 Also see `Log File Formats`_.
06842027 3133
f80dba8d 3134.. option:: log_hist_msec=int
06842027 3135
f80dba8d
MT
3136 Same as :option:`log_avg_msec`, but logs entries for completion latency
3137 histograms. Computing latency percentiles from averages of intervals using
c60ebc45 3138 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
f80dba8d
MT
3139 histogram entries over the specified period of time, reducing log sizes for
3140 high IOPS devices while retaining percentile accuracy. See
074f0817
SW
3141 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
3142 Defaults to 0, meaning histogram logging is disabled.
06842027 3143
f80dba8d 3144.. option:: log_hist_coarseness=int
06842027 3145
f80dba8d
MT
3146 Integer ranging from 0 to 6, defining the coarseness of the resolution of
3147 the histogram logs enabled with :option:`log_hist_msec`. For each increment
3148 in coarseness, fio outputs half as many bins. Defaults to 0, for which
074f0817
SW
3149 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
3150 and `Log File Formats`_.
8b28bd41 3151
f80dba8d 3152.. option:: log_max_value=bool
66c098b8 3153
f80dba8d
MT
3154 If :option:`log_avg_msec` is set, fio logs the average over that window. If
3155 you instead want to log the maximum value, set this option to 1. Defaults to
3156 0, meaning that averaged values are logged.
a696fa2a 3157
589e88b7 3158.. option:: log_offset=bool
a696fa2a 3159
f80dba8d 3160 If this is set, the iolog options will include the byte offset for the I/O
5a83478f
SW
3161 entry as well as the other data values. Defaults to 0 meaning that
3162 offsets are not present in logs. Also see `Log File Formats`_.
71bfa161 3163
f80dba8d 3164.. option:: log_compression=int
7de87099 3165
f80dba8d
MT
3166 If this is set, fio will compress the I/O logs as it goes, to keep the
3167 memory footprint lower. When a log reaches the specified size, that chunk is
3168 removed and compressed in the background. Given that I/O logs are fairly
3169 highly compressible, this yields a nice memory savings for longer runs. The
3170 downside is that the compression will consume some background CPU cycles, so
3171 it may impact the run. This, however, is also true if the logging ends up
3172 consuming most of the system memory. So pick your poison. The I/O logs are
3173 saved normally at the end of a run, by decompressing the chunks and storing
3174 them in the specified log file. This feature depends on the availability of
3175 zlib.
e0b0d892 3176
f80dba8d 3177.. option:: log_compression_cpus=str
e0b0d892 3178
f80dba8d
MT
3179 Define the set of CPUs that are allowed to handle online log compression for
3180 the I/O jobs. This can provide better isolation between performance
0cf90a62
SW
3181 sensitive jobs, and background compression work. See
3182 :option:`cpus_allowed` for the format used.
9e684a49 3183
f80dba8d 3184.. option:: log_store_compressed=bool
9e684a49 3185
f80dba8d
MT
3186 If set, fio will store the log files in a compressed format. They can be
3187 decompressed with fio, using the :option:`--inflate-log` command line
3188 parameter. The files will be stored with a :file:`.fz` suffix.
9e684a49 3189
f80dba8d 3190.. option:: log_unix_epoch=bool
9e684a49 3191
f80dba8d
MT
3192 If set, fio will log Unix timestamps to the log files produced by enabling
3193 write_type_log for each log type, instead of the default zero-based
3194 timestamps.
3195
3196.. option:: block_error_percentiles=bool
3197
3198 If set, record errors in trim block-sized units from writes and trims and
3199 output a histogram of how many trims it took to get to errors, and what kind
3200 of error was encountered.
3201
3202.. option:: bwavgtime=int
3203
3204 Average the calculated bandwidth over the given time. Value is specified in
3205 milliseconds. If the job also does bandwidth logging through
3206 :option:`write_bw_log`, then the minimum of this option and
3207 :option:`log_avg_msec` will be used. Default: 500ms.
3208
3209.. option:: iopsavgtime=int
3210
3211 Average the calculated IOPS over the given time. Value is specified in
3212 milliseconds. If the job also does IOPS logging through
3213 :option:`write_iops_log`, then the minimum of this option and
3214 :option:`log_avg_msec` will be used. Default: 500ms.
3215
3216.. option:: disk_util=bool
3217
3218 Generate disk utilization statistics, if the platform supports it.
3219 Default: true.
3220
3221.. option:: disable_lat=bool
3222
3223 Disable measurements of total latency numbers. Useful only for cutting back
3224 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
3225 performance at really high IOPS rates. Note that to really get rid of a
3226 large amount of these calls, this option must be used with
f75ede1d 3227 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
f80dba8d
MT
3228
3229.. option:: disable_clat=bool
3230
3231 Disable measurements of completion latency numbers. See
3232 :option:`disable_lat`.
3233
3234.. option:: disable_slat=bool
3235
3236 Disable measurements of submission latency numbers. See
f50fbdda 3237 :option:`disable_lat`.
f80dba8d 3238
f75ede1d 3239.. option:: disable_bw_measurement=bool, disable_bw=bool
f80dba8d
MT
3240
3241 Disable measurements of throughput/bandwidth numbers. See
3242 :option:`disable_lat`.
3243
3244.. option:: clat_percentiles=bool
3245
b599759b
JA
3246 Enable the reporting of percentiles of completion latencies. This
3247 option is mutually exclusive with :option:`lat_percentiles`.
3248
3249.. option:: lat_percentiles=bool
3250
b71968b1 3251 Enable the reporting of percentiles of I/O latencies. This is similar
b599759b
JA
3252 to :option:`clat_percentiles`, except that this includes the
3253 submission latency. This option is mutually exclusive with
3254 :option:`clat_percentiles`.
f80dba8d
MT
3255
3256.. option:: percentile_list=float_list
3257
c32ba107
JA
3258 Overwrite the default list of percentiles for completion latencies and
3259 the block error histogram. Each number is a floating number in the
3260 range (0,100], and the maximum length of the list is 20. Use ``:`` to
3261 separate the numbers, and list the numbers in ascending order. For
3262 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
3263 values of completion latency below which 99.5% and 99.9% of the observed
3264 latencies fell, respectively.
f80dba8d 3265
e883cb35
JF
3266.. option:: significant_figures=int
3267
c32ba107
JA
3268 If using :option:`--output-format` of `normal`, set the significant
3269 figures to this value. Higher values will yield more precise IOPS and
3270 throughput units, while lower values will round. Requires a minimum
3271 value of 1 and a maximum value of 10. Defaults to 4.
e883cb35 3272
f80dba8d
MT
3273
3274Error handling
3275~~~~~~~~~~~~~~
3276
3277.. option:: exitall_on_error
3278
3279 When one job finishes in error, terminate the rest. The default is to wait
3280 for each job to finish.
3281
3282.. option:: continue_on_error=str
3283
3284 Normally fio will exit the job on the first observed failure. If this option
3285 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
3286 EILSEQ) until the runtime is exceeded or the I/O size specified is
3287 completed. If this option is used, there are two more stats that are
3288 appended, the total error count and the first error. The error field given
3289 in the stats is the first error that was hit during the run.
3290
3291 The allowed values are:
3292
3293 **none**
3294 Exit on any I/O or verify errors.
3295
3296 **read**
3297 Continue on read errors, exit on all others.
3298
3299 **write**
3300 Continue on write errors, exit on all others.
3301
3302 **io**
3303 Continue on any I/O error, exit on all others.
3304
3305 **verify**
3306 Continue on verify errors, exit on all others.
3307
3308 **all**
3309 Continue on all errors.
3310
3311 **0**
3312 Backward-compatible alias for 'none'.
3313
3314 **1**
3315 Backward-compatible alias for 'all'.
3316
3317.. option:: ignore_error=str
3318
3319 Sometimes you want to ignore some errors during test in that case you can
a35ef7cb
TK
3320 specify error list for each error type, instead of only being able to
3321 ignore the default 'non-fatal error' using :option:`continue_on_error`.
f80dba8d
MT
3322 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
3323 given error type is separated with ':'. Error may be symbol ('ENOSPC',
3324 'ENOMEM') or integer. Example::
3325
3326 ignore_error=EAGAIN,ENOSPC:122
3327
3328 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
a35ef7cb
TK
3329 WRITE. This option works by overriding :option:`continue_on_error` with
3330 the list of errors for each error type if any.
f80dba8d
MT
3331
3332.. option:: error_dump=bool
3333
3334 If set dump every error even if it is non fatal, true by default. If
3335 disabled only fatal error will be dumped.
3336
f75ede1d
SW
3337Running predefined workloads
3338----------------------------
3339
3340Fio includes predefined profiles that mimic the I/O workloads generated by
3341other tools.
3342
3343.. option:: profile=str
3344
3345 The predefined workload to run. Current profiles are:
3346
3347 **tiobench**
3348 Threaded I/O bench (tiotest/tiobench) like workload.
3349
3350 **act**
3351 Aerospike Certification Tool (ACT) like workload.
3352
3353To view a profile's additional options use :option:`--cmdhelp` after specifying
3354the profile. For example::
3355
f50fbdda 3356 $ fio --profile=act --cmdhelp
f75ede1d
SW
3357
3358Act profile options
3359~~~~~~~~~~~~~~~~~~~
3360
3361.. option:: device-names=str
3362 :noindex:
3363
3364 Devices to use.
3365
3366.. option:: load=int
3367 :noindex:
3368
3369 ACT load multiplier. Default: 1.
3370
3371.. option:: test-duration=time
3372 :noindex:
3373
947e0fe0
SW
3374 How long the entire test takes to run. When the unit is omitted, the value
3375 is given in seconds. Default: 24h.
f75ede1d
SW
3376
3377.. option:: threads-per-queue=int
3378 :noindex:
3379
f50fbdda 3380 Number of read I/O threads per device. Default: 8.
f75ede1d
SW
3381
3382.. option:: read-req-num-512-blocks=int
3383 :noindex:
3384
3385 Number of 512B blocks to read at the time. Default: 3.
3386
3387.. option:: large-block-op-kbytes=int
3388 :noindex:
3389
3390 Size of large block ops in KiB (writes). Default: 131072.
3391
3392.. option:: prep
3393 :noindex:
3394
3395 Set to run ACT prep phase.
3396
3397Tiobench profile options
3398~~~~~~~~~~~~~~~~~~~~~~~~
3399
3400.. option:: size=str
3401 :noindex:
3402
f50fbdda 3403 Size in MiB.
f75ede1d
SW
3404
3405.. option:: block=int
3406 :noindex:
3407
3408 Block size in bytes. Default: 4096.
3409
3410.. option:: numruns=int
3411 :noindex:
3412
3413 Number of runs.
3414
3415.. option:: dir=str
3416 :noindex:
3417
3418 Test directory.
3419
3420.. option:: threads=int
3421 :noindex:
3422
3423 Number of threads.
f80dba8d
MT
3424
3425Interpreting the output
3426-----------------------
3427
36214730
SW
3428..
3429 Example output was based on the following:
3430 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
3431 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
3432 --runtime=2m --rw=rw
3433
f80dba8d
MT
3434Fio spits out a lot of output. While running, fio will display the status of the
3435jobs created. An example of that would be::
3436
9d25d068 3437 Jobs: 1 (f=1): [_(1),M(1)][24.8%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 01m:31s]
f80dba8d 3438
36214730
SW
3439The characters inside the first set of square brackets denote the current status of
3440each thread. The first character is the first job defined in the job file, and so
3441forth. The possible values (in typical life cycle order) are:
f80dba8d
MT
3442
3443+------+-----+-----------------------------------------------------------+
3444| Idle | Run | |
3445+======+=====+===========================================================+
3446| P | | Thread setup, but not started. |
3447+------+-----+-----------------------------------------------------------+
3448| C | | Thread created. |
3449+------+-----+-----------------------------------------------------------+
3450| I | | Thread initialized, waiting or generating necessary data. |
3451+------+-----+-----------------------------------------------------------+
3452| | p | Thread running pre-reading file(s). |
3453+------+-----+-----------------------------------------------------------+
36214730
SW
3454| | / | Thread is in ramp period. |
3455+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3456| | R | Running, doing sequential reads. |
3457+------+-----+-----------------------------------------------------------+
3458| | r | Running, doing random reads. |
3459+------+-----+-----------------------------------------------------------+
3460| | W | Running, doing sequential writes. |
3461+------+-----+-----------------------------------------------------------+
3462| | w | Running, doing random writes. |
3463+------+-----+-----------------------------------------------------------+
3464| | M | Running, doing mixed sequential reads/writes. |
3465+------+-----+-----------------------------------------------------------+
3466| | m | Running, doing mixed random reads/writes. |
3467+------+-----+-----------------------------------------------------------+
36214730
SW
3468| | D | Running, doing sequential trims. |
3469+------+-----+-----------------------------------------------------------+
3470| | d | Running, doing random trims. |
3471+------+-----+-----------------------------------------------------------+
3472| | F | Running, currently waiting for :manpage:`fsync(2)`. |
f80dba8d
MT
3473+------+-----+-----------------------------------------------------------+
3474| | V | Running, doing verification of written data. |
3475+------+-----+-----------------------------------------------------------+
36214730
SW
3476| f | | Thread finishing. |
3477+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3478| E | | Thread exited, not reaped by main thread yet. |
3479+------+-----+-----------------------------------------------------------+
36214730 3480| _ | | Thread reaped. |
f80dba8d
MT
3481+------+-----+-----------------------------------------------------------+
3482| X | | Thread reaped, exited with an error. |
3483+------+-----+-----------------------------------------------------------+
3484| K | | Thread reaped, exited due to signal. |
3485+------+-----+-----------------------------------------------------------+
3486
36214730
SW
3487..
3488 Example output was based on the following:
3489 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
3490 --time_based --rate=2512k --bs=256K --numjobs=10 \
3491 --name=readers --rw=read --name=writers --rw=write
3492
f80dba8d 3493Fio will condense the thread string as not to take up more space on the command
36214730 3494line than needed. For instance, if you have 10 readers and 10 writers running,
f80dba8d
MT
3495the output would look like this::
3496
9d25d068 3497 Jobs: 20 (f=20): [R(10),W(10)][4.0%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 57m:36s]
f80dba8d 3498
36214730
SW
3499Note that the status string is displayed in order, so it's possible to tell which of
3500the jobs are currently doing what. In the example above this means that jobs 1--10
3501are readers and 11--20 are writers.
f80dba8d
MT
3502
3503The other values are fairly self explanatory -- number of threads currently
36214730
SW
3504running and doing I/O, the number of currently open files (f=), the estimated
3505completion percentage, the rate of I/O since last check (read speed listed first,
f50fbdda
TK
3506then write speed and optionally trim speed) in terms of bandwidth and IOPS,
3507and time to completion for the current running group. It's impossible to estimate
3508runtime of the following groups (if any).
36214730
SW
3509
3510..
3511 Example output was based on the following:
3512 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
3513 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
3514 --bs=7K --name=Client1 --rw=write
3515
3516When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
3517each thread, group of threads, and disks in that order. For each overall thread (or
3518group) the output looks like::
3519
3520 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
3521 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
3522 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
3523 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
3524 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
3525 clat percentiles (usec):
3526 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
3527 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
3528 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
3529 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
3530 | 99.99th=[78119]
3531 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
3532 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
29092211
VF
3533 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
3534 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
3535 lat (msec) : 100=0.65%
36214730
SW
3536 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
3537 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
3538 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3539 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3540 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
3541 latency : target=0, window=0, percentile=100.00%, depth=8
3542
3543The job name (or first job's name when using :option:`group_reporting`) is printed,
3544along with the group id, count of jobs being aggregated, last error id seen (which
3545is 0 when there are no errors), pid/tid of that thread and the time the job/group
3546completed. Below are the I/O statistics for each data direction performed (showing
3547writes in the example above). In the order listed, they denote:
3548
3549**read/write/trim**
3550 The string before the colon shows the I/O direction the statistics
3551 are for. **IOPS** is the average I/Os performed per second. **BW**
3552 is the average bandwidth rate shown as: value in power of 2 format
3553 (value in power of 10 format). The last two values show: (**total
3554 I/O performed** in power of 2 format / **runtime** of that thread).
f80dba8d
MT
3555
3556**slat**
36214730
SW
3557 Submission latency (**min** being the minimum, **max** being the
3558 maximum, **avg** being the average, **stdev** being the standard
3559 deviation). This is the time it took to submit the I/O. For
3560 sync I/O this row is not displayed as the slat is really the
3561 completion latency (since queue/complete is one operation there).
3562 This value can be in nanoseconds, microseconds or milliseconds ---
3563 fio will choose the most appropriate base and print that (in the
3564 example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
0d237712 3565 latencies are always expressed in microseconds.
f80dba8d
MT
3566
3567**clat**
3568 Completion latency. Same names as slat, this denotes the time from
3569 submission to completion of the I/O pieces. For sync I/O, clat will
3570 usually be equal (or very close) to 0, as the time from submit to
3571 complete is basically just CPU time (I/O has already been done, see slat
3572 explanation).
3573
29092211
VF
3574**lat**
3575 Total latency. Same names as slat and clat, this denotes the time from
3576 when fio created the I/O unit to completion of the I/O operation.
3577
f80dba8d 3578**bw**
36214730
SW
3579 Bandwidth statistics based on samples. Same names as the xlat stats,
3580 but also includes the number of samples taken (**samples**) and an
3581 approximate percentage of total aggregate bandwidth this thread
3582 received in its group (**per**). This last value is only really
3583 useful if the threads in this group are on the same disk, since they
3584 are then competing for disk access.
3585
3586**iops**
3587 IOPS statistics based on samples. Same names as bw.
f80dba8d 3588
29092211
VF
3589**lat (nsec/usec/msec)**
3590 The distribution of I/O completion latencies. This is the time from when
3591 I/O leaves fio and when it gets completed. Unlike the separate
3592 read/write/trim sections above, the data here and in the remaining
3593 sections apply to all I/Os for the reporting group. 250=0.04% means that
3594 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
3595 of the I/Os required 250 to 499us for completion.
3596
f80dba8d
MT
3597**cpu**
3598 CPU usage. User and system time, along with the number of context
3599 switches this thread went through, usage of system and user time, and
3600 finally the number of major and minor page faults. The CPU utilization
3601 numbers are averages for the jobs in that reporting group, while the
23a8e176 3602 context and fault counters are summed.
f80dba8d
MT
3603
3604**IO depths**
a2140525
SW
3605 The distribution of I/O depths over the job lifetime. The numbers are
3606 divided into powers of 2 and each entry covers depths from that value
3607 up to those that are lower than the next entry -- e.g., 16= covers
3608 depths from 16 to 31. Note that the range covered by a depth
3609 distribution entry can be different to the range covered by the
3610 equivalent submit/complete distribution entry.
f80dba8d
MT
3611
3612**IO submit**
3613 How many pieces of I/O were submitting in a single submit call. Each
c60ebc45 3614 entry denotes that amount and below, until the previous entry -- e.g.,
a2140525
SW
3615 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
3616 call. Note that the range covered by a submit distribution entry can
3617 be different to the range covered by the equivalent depth distribution
3618 entry.
f80dba8d
MT
3619
3620**IO complete**
3621 Like the above submit number, but for completions instead.
3622
36214730
SW
3623**IO issued rwt**
3624 The number of read/write/trim requests issued, and how many of them were
3625 short or dropped.
f80dba8d 3626
29092211 3627**IO latency**
ee21ebee 3628 These values are for :option:`latency_target` and related options. When
29092211
VF
3629 these options are engaged, this section describes the I/O depth required
3630 to meet the specified latency target.
71bfa161 3631
36214730
SW
3632..
3633 Example output was based on the following:
3634 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
3635 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
3636 --rate=11M --name=write --rw=write --bs=2k --rate=700k
3637
71bfa161 3638After each client has been listed, the group statistics are printed. They
f80dba8d 3639will look like this::
71bfa161 3640
f80dba8d 3641 Run status group 0 (all jobs):
36214730
SW
3642 READ: bw=20.9MiB/s (21.9MB/s), 10.4MiB/s-10.8MiB/s (10.9MB/s-11.3MB/s), io=64.0MiB (67.1MB), run=2973-3069msec
3643 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
71bfa161 3644
36214730 3645For each data direction it prints:
71bfa161 3646
36214730
SW
3647**bw**
3648 Aggregate bandwidth of threads in this group followed by the
3649 minimum and maximum bandwidth of all the threads in this group.
3650 Values outside of brackets are power-of-2 format and those
3651 within are the equivalent value in a power-of-10 format.
f80dba8d 3652**io**
36214730
SW
3653 Aggregate I/O performed of all threads in this group. The
3654 format is the same as bw.
3655**run**
3656 The smallest and longest runtimes of the threads in this group.
71bfa161 3657
f50fbdda 3658And finally, the disk statistics are printed. This is Linux specific. They will look like this::
71bfa161 3659
f80dba8d
MT
3660 Disk stats (read/write):
3661 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
71bfa161
JA
3662
3663Each value is printed for both reads and writes, with reads first. The
3664numbers denote:
3665
f80dba8d 3666**ios**
c60ebc45 3667 Number of I/Os performed by all groups.
f80dba8d 3668**merge**
007c7be9 3669 Number of merges performed by the I/O scheduler.
f80dba8d
MT
3670**ticks**
3671 Number of ticks we kept the disk busy.
36214730 3672**in_queue**
f80dba8d
MT
3673 Total time spent in the disk queue.
3674**util**
3675 The disk utilization. A value of 100% means we kept the disk
71bfa161
JA
3676 busy constantly, 50% would be a disk idling half of the time.
3677
f80dba8d
MT
3678It is also possible to get fio to dump the current output while it is running,
3679without terminating the job. To do that, send fio the **USR1** signal. You can
3680also get regularly timed dumps by using the :option:`--status-interval`
3681parameter, or by creating a file in :file:`/tmp` named
3682:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
3683current output status.
8423bd11 3684
71bfa161 3685
f80dba8d
MT
3686Terse output
3687------------
71bfa161 3688
f80dba8d
MT
3689For scripted usage where you typically want to generate tables or graphs of the
3690results, fio can output the results in a semicolon separated format. The format
3691is one long line of values, such as::
71bfa161 3692
f80dba8d
MT
3693 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%
3694 A description of this job goes here.
562c2d2f 3695
4e757af1
VF
3696The job description (if provided) follows on a second line for terse v2.
3697It appears on the same line for other terse versions.
71bfa161 3698
a7f77fa6
SW
3699To enable terse output, use the :option:`--minimal` or
3700:option:`--output-format`\=terse command line options. The
f80dba8d
MT
3701first value is the version of the terse output format. If the output has to be
3702changed for some reason, this number will be incremented by 1 to signify that
3703change.
6820cb3b 3704
a2c95580 3705Split up, the format is as follows (comments in brackets denote when a
007c7be9 3706field was introduced or whether it's specific to some terse version):
71bfa161 3707
f80dba8d
MT
3708 ::
3709
f50fbdda 3710 terse version, fio version [v3], jobname, groupid, error
f80dba8d
MT
3711
3712 READ status::
3713
3714 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3715 Submission latency: min, max, mean, stdev (usec)
3716 Completion latency: min, max, mean, stdev (usec)
3717 Completion latency percentiles: 20 fields (see below)
3718 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3719 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3720 IOPS [v5]: min, max, mean, stdev, number of samples
f80dba8d
MT
3721
3722 WRITE status:
3723
3724 ::
3725
3726 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3727 Submission latency: min, max, mean, stdev (usec)
247823cc 3728 Completion latency: min, max, mean, stdev (usec)
f80dba8d
MT
3729 Completion latency percentiles: 20 fields (see below)
3730 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3731 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3732 IOPS [v5]: min, max, mean, stdev, number of samples
a2c95580
AH
3733
3734 TRIM status [all but version 3]:
3735
f50fbdda 3736 Fields are similar to READ/WRITE status.
f80dba8d
MT
3737
3738 CPU usage::
3739
3740 user, system, context switches, major faults, minor faults
3741
3742 I/O depths::
3743
3744 <=1, 2, 4, 8, 16, 32, >=64
3745
3746 I/O latencies microseconds::
3747
3748 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
3749
3750 I/O latencies milliseconds::
3751
3752 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
3753
a2c95580 3754 Disk utilization [v3]::
f80dba8d 3755
f50fbdda
TK
3756 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
3757 time spent in queue, disk utilization percentage
f80dba8d
MT
3758
3759 Additional Info (dependent on continue_on_error, default off)::
3760
3761 total # errors, first error code
3762
3763 Additional Info (dependent on description being set)::
3764
3765 Text description
3766
3767Completion latency percentiles can be a grouping of up to 20 sets, so for the
3768terse output fio writes all of them. Each field will look like this::
1db92cb6 3769
f50fbdda 3770 1.00%=6112
1db92cb6 3771
f80dba8d 3772which is the Xth percentile, and the `usec` latency associated with it.
1db92cb6 3773
f50fbdda 3774For `Disk utilization`, all disks used by fio are shown. So for each disk there
f80dba8d 3775will be a disk utilization section.
f2f788dd 3776
2fc26c3d 3777Below is a single line containing short names for each of the fields in the
2831be97 3778minimal output v3, separated by semicolons::
2fc26c3d 3779
f50fbdda 3780 terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth;read_iops;read_runtime_ms;read_slat_min;read_slat_max;read_slat_mean;read_slat_dev;read_clat_min;read_clat_max;read_clat_mean;read_clat_dev;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min;read_lat_max;read_lat_mean;read_lat_dev;read_bw_min;read_bw_max;read_bw_agg_pct;read_bw_mean;read_bw_dev;write_kb;write_bandwidth;write_iops;write_runtime_ms;write_slat_min;write_slat_max;write_slat_mean;write_slat_dev;write_clat_min;write_clat_max;write_clat_mean;write_clat_dev;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min;write_lat_max;write_lat_mean;write_lat_dev;write_bw_min;write_bw_max;write_bw_agg_pct;write_bw_mean;write_bw_dev;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util
2fc26c3d 3781
4e757af1
VF
3782In client/server mode terse output differs from what appears when jobs are run
3783locally. Disk utilization data is omitted from the standard terse output and
3784for v3 and later appears on its own separate line at the end of each terse
3785reporting cycle.
3786
25c8b9d7 3787
44c82dba
VF
3788JSON output
3789------------
3790
3791The `json` output format is intended to be both human readable and convenient
3792for automated parsing. For the most part its sections mirror those of the
3793`normal` output. The `runtime` value is reported in msec and the `bw` value is
3794reported in 1024 bytes per second units.