Remove verifysort/verifysort_nr from documentation
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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.
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102
103.. option:: --output=filename
104
105 Write output to file `filename`.
106
f50fbdda 107.. option:: --output-format=format
b8f7e412 108
f50fbdda 109 Set the reporting `format` to `normal`, `terse`, `json`, or `json+`. Multiple
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110 formats can be selected, separated by a comma. `terse` is a CSV based
111 format. `json+` is like `json`, except it adds a full dump of the latency
112 buckets.
113
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114.. option:: --bandwidth-log
115
116 Generate aggregate bandwidth logs.
117
118.. option:: --minimal
119
120 Print statistics in a terse, semicolon-delimited format.
121
122.. option:: --append-terse
123
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124 Print statistics in selected mode AND terse, semicolon-delimited format.
125 **Deprecated**, use :option:`--output-format` instead to select multiple
126 formats.
f80dba8d 127
f50fbdda 128.. option:: --terse-version=version
f80dba8d 129
f50fbdda 130 Set terse `version` output format (default 3, or 2 or 4 or 5).
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131
132.. option:: --version
133
b8f7e412 134 Print version information and exit.
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135
136.. option:: --help
137
113f0e7c 138 Print a summary of the command line options and exit.
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139
140.. option:: --cpuclock-test
141
142 Perform test and validation of internal CPU clock.
143
113f0e7c 144.. option:: --crctest=[test]
f80dba8d 145
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146 Test the speed of the built-in checksumming functions. If no argument is
147 given, all of them are tested. Alternatively, a comma separated list can
148 be passed, in which case the given ones are tested.
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149
150.. option:: --cmdhelp=command
151
152 Print help information for `command`. May be ``all`` for all commands.
153
154.. option:: --enghelp=[ioengine[,command]]
155
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156 List all commands defined by `ioengine`, or print help for `command`
157 defined by `ioengine`. If no `ioengine` is given, list all
b034c0dd 158 available ioengines.
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159
160.. option:: --showcmd=jobfile
161
b8f7e412 162 Convert `jobfile` to a set of command-line options.
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163
164.. option:: --readonly
165
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166 Turn on safety read-only checks, preventing writes. The ``--readonly``
167 option is an extra safety guard to prevent users from accidentally starting
168 a write workload when that is not desired. Fio will only write if
169 `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used
170 as an extra precaution as ``--readonly`` will also enable a write check in
171 the I/O engine core to prevent writes due to unknown user space bug(s).
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172
173.. option:: --eta=when
174
b8f7e412 175 Specifies when real-time ETA estimate should be printed. `when` may be
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176 `always`, `never` or `auto`. `auto` is the default, it prints ETA
177 when requested if the output is a TTY. `always` disregards the output
178 type, and prints ETA when requested. `never` never prints ETA.
179
180.. option:: --eta-interval=time
181
182 By default, fio requests client ETA status roughly every second. With
183 this option, the interval is configurable. Fio imposes a minimum
184 allowed time to avoid flooding the console, less than 250 msec is
185 not supported.
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186
187.. option:: --eta-newline=time
188
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189 Force a new line for every `time` period passed. When the unit is omitted,
190 the value is interpreted in seconds.
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191
192.. option:: --status-interval=time
193
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194 Force a full status dump of cumulative (from job start) values at `time`
195 intervals. This option does *not* provide per-period measurements. So
196 values such as bandwidth are running averages. When the time unit is omitted,
197 `time` is interpreted in seconds.
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198
199.. option:: --section=name
200
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201 Only run specified section `name` in job file. Multiple sections can be specified.
202 The ``--section`` option allows one to combine related jobs into one file.
203 E.g. one job file could define light, moderate, and heavy sections. Tell
204 fio to run only the "heavy" section by giving ``--section=heavy``
205 command line option. One can also specify the "write" operations in one
206 section and "verify" operation in another section. The ``--section`` option
207 only applies to job sections. The reserved *global* section is always
208 parsed and used.
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209
210.. option:: --alloc-size=kb
211
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212 Set the internal smalloc pool size to `kb` in KiB. The
213 ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
214 If running large jobs with randommap enabled, fio can run out of memory.
215 Smalloc is an internal allocator for shared structures from a fixed size
216 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
f80dba8d 217
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218 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
219 in :file:`/tmp`.
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220
221.. option:: --warnings-fatal
222
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223 All fio parser warnings are fatal, causing fio to exit with an
224 error.
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225
226.. option:: --max-jobs=nr
227
f50fbdda 228 Set the maximum number of threads/processes to support to `nr`.
818322cc 229 NOTE: On Linux, it may be necessary to increase the shared-memory
71aa48eb 230 limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
818322cc 231 creating jobs.
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232
233.. option:: --server=args
234
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235 Start a backend server, with `args` specifying what to listen to.
236 See `Client/Server`_ section.
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237
238.. option:: --daemonize=pidfile
239
b034c0dd 240 Background a fio server, writing the pid to the given `pidfile` file.
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241
242.. option:: --client=hostname
243
f50fbdda 244 Instead of running the jobs locally, send and run them on the given `hostname`
71aa48eb 245 or set of `hostname`\s. See `Client/Server`_ section.
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246
247.. option:: --remote-config=file
248
f50fbdda 249 Tell fio server to load this local `file`.
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250
251.. option:: --idle-prof=option
252
b8f7e412 253 Report CPU idleness. `option` is one of the following:
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254
255 **calibrate**
256 Run unit work calibration only and exit.
257
258 **system**
259 Show aggregate system idleness and unit work.
260
261 **percpu**
262 As **system** but also show per CPU idleness.
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263
264.. option:: --inflate-log=log
265
f50fbdda 266 Inflate and output compressed `log`.
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267
268.. option:: --trigger-file=file
269
f50fbdda 270 Execute trigger command when `file` exists.
f80dba8d 271
f50fbdda 272.. option:: --trigger-timeout=time
f80dba8d 273
f50fbdda 274 Execute trigger at this `time`.
f80dba8d 275
f50fbdda 276.. option:: --trigger=command
f80dba8d 277
f50fbdda 278 Set this `command` as local trigger.
f80dba8d 279
f50fbdda 280.. option:: --trigger-remote=command
f80dba8d 281
f50fbdda 282 Set this `command` as remote trigger.
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283
284.. option:: --aux-path=path
285
f50fbdda 286 Use this `path` for fio state generated files.
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287
288Any parameters following the options will be assumed to be job files, unless
289they match a job file parameter. Multiple job files can be listed and each job
290file will be regarded as a separate group. Fio will :option:`stonewall`
291execution between each group.
292
293
294Job file format
295---------------
296
297As previously described, fio accepts one or more job files describing what it is
298supposed to do. The job file format is the classic ini file, where the names
c60ebc45 299enclosed in [] brackets define the job name. You are free to use any ASCII name
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300you want, except *global* which has special meaning. Following the job name is
301a sequence of zero or more parameters, one per line, that define the behavior of
302the job. If the first character in a line is a ';' or a '#', the entire line is
303discarded as a comment.
304
305A *global* section sets defaults for the jobs described in that file. A job may
306override a *global* section parameter, and a job file may even have several
307*global* sections if so desired. A job is only affected by a *global* section
308residing above it.
309
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310The :option:`--cmdhelp` option also lists all options. If used with a `command`
311argument, :option:`--cmdhelp` will detail the given `command`.
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312
313See the `examples/` directory for inspiration on how to write job files. Note
314the copyright and license requirements currently apply to `examples/` files.
315
316So let's look at a really simple job file that defines two processes, each
317randomly reading from a 128MiB file:
318
319.. code-block:: ini
320
321 ; -- start job file --
322 [global]
323 rw=randread
324 size=128m
325
326 [job1]
327
328 [job2]
329
330 ; -- end job file --
331
332As you can see, the job file sections themselves are empty as all the described
333parameters are shared. As no :option:`filename` option is given, fio makes up a
334`filename` for each of the jobs as it sees fit. On the command line, this job
335would look as follows::
336
337$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
338
339
340Let's look at an example that has a number of processes writing randomly to
341files:
342
343.. code-block:: ini
344
345 ; -- start job file --
346 [random-writers]
347 ioengine=libaio
348 iodepth=4
349 rw=randwrite
350 bs=32k
351 direct=0
352 size=64m
353 numjobs=4
354 ; -- end job file --
355
356Here we have no *global* section, as we only have one job defined anyway. We
357want to use async I/O here, with a depth of 4 for each file. We also increased
358the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
359jobs. The result is 4 processes each randomly writing to their own 64MiB
360file. Instead of using the above job file, you could have given the parameters
361on the command line. For this case, you would specify::
362
363$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
364
365When fio is utilized as a basis of any reasonably large test suite, it might be
366desirable to share a set of standardized settings across multiple job files.
367Instead of copy/pasting such settings, any section may pull in an external
368:file:`filename.fio` file with *include filename* directive, as in the following
369example::
370
371 ; -- start job file including.fio --
372 [global]
373 filename=/tmp/test
374 filesize=1m
375 include glob-include.fio
376
377 [test]
378 rw=randread
379 bs=4k
380 time_based=1
381 runtime=10
382 include test-include.fio
383 ; -- end job file including.fio --
384
385.. code-block:: ini
386
387 ; -- start job file glob-include.fio --
388 thread=1
389 group_reporting=1
390 ; -- end job file glob-include.fio --
391
392.. code-block:: ini
393
394 ; -- start job file test-include.fio --
395 ioengine=libaio
396 iodepth=4
397 ; -- end job file test-include.fio --
398
399Settings pulled into a section apply to that section only (except *global*
400section). Include directives may be nested in that any included file may contain
401further include directive(s). Include files may not contain [] sections.
402
403
404Environment variables
405~~~~~~~~~~~~~~~~~~~~~
406
407Fio also supports environment variable expansion in job files. Any sub-string of
408the form ``${VARNAME}`` as part of an option value (in other words, on the right
409of the '='), will be expanded to the value of the environment variable called
410`VARNAME`. If no such environment variable is defined, or `VARNAME` is the
411empty string, the empty string will be substituted.
412
413As an example, let's look at a sample fio invocation and job file::
414
415$ SIZE=64m NUMJOBS=4 fio jobfile.fio
416
417.. code-block:: ini
418
419 ; -- start job file --
420 [random-writers]
421 rw=randwrite
422 size=${SIZE}
423 numjobs=${NUMJOBS}
424 ; -- end job file --
425
426This will expand to the following equivalent job file at runtime:
427
428.. code-block:: ini
429
430 ; -- start job file --
431 [random-writers]
432 rw=randwrite
433 size=64m
434 numjobs=4
435 ; -- end job file --
436
437Fio ships with a few example job files, you can also look there for inspiration.
438
439Reserved keywords
440~~~~~~~~~~~~~~~~~
441
442Additionally, fio has a set of reserved keywords that will be replaced
443internally with the appropriate value. Those keywords are:
444
445**$pagesize**
446
447 The architecture page size of the running system.
448
449**$mb_memory**
450
451 Megabytes of total memory in the system.
452
453**$ncpus**
454
455 Number of online available CPUs.
456
457These can be used on the command line or in the job file, and will be
458automatically substituted with the current system values when the job is
459run. Simple math is also supported on these keywords, so you can perform actions
460like::
461
b034c0dd 462 size=8*$mb_memory
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463
464and get that properly expanded to 8 times the size of memory in the machine.
465
466
467Job file parameters
468-------------------
469
470This section describes in details each parameter associated with a job. Some
471parameters take an option of a given type, such as an integer or a
472string. Anywhere a numeric value is required, an arithmetic expression may be
473used, provided it is surrounded by parentheses. Supported operators are:
474
475 - addition (+)
476 - subtraction (-)
477 - multiplication (*)
478 - division (/)
479 - modulus (%)
480 - exponentiation (^)
481
482For time values in expressions, units are microseconds by default. This is
483different than for time values not in expressions (not enclosed in
484parentheses). The following types are used:
485
486
487Parameter types
488~~~~~~~~~~~~~~~
489
490**str**
b034c0dd 491 String: A sequence of alphanumeric characters.
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492
493**time**
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494 Integer with possible time suffix. Without a unit value is interpreted as
495 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
496 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
497 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
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498
499.. _int:
500
501**int**
502 Integer. A whole number value, which may contain an integer prefix
503 and an integer suffix:
504
b034c0dd 505 [*integer prefix*] **number** [*integer suffix*]
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506
507 The optional *integer prefix* specifies the number's base. The default
508 is decimal. *0x* specifies hexadecimal.
509
510 The optional *integer suffix* specifies the number's units, and includes an
511 optional unit prefix and an optional unit. For quantities of data, the
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512 default unit is bytes. For quantities of time, the default unit is seconds
513 unless otherwise specified.
f80dba8d 514
9207a0cb 515 With :option:`kb_base`\=1000, fio follows international standards for unit
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516 prefixes. To specify power-of-10 decimal values defined in the
517 International System of Units (SI):
518
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519 * *K* -- means kilo (K) or 1000
520 * *M* -- means mega (M) or 1000**2
521 * *G* -- means giga (G) or 1000**3
522 * *T* -- means tera (T) or 1000**4
523 * *P* -- means peta (P) or 1000**5
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524
525 To specify power-of-2 binary values defined in IEC 80000-13:
526
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527 * *Ki* -- means kibi (Ki) or 1024
528 * *Mi* -- means mebi (Mi) or 1024**2
529 * *Gi* -- means gibi (Gi) or 1024**3
530 * *Ti* -- means tebi (Ti) or 1024**4
531 * *Pi* -- means pebi (Pi) or 1024**5
f80dba8d 532
9207a0cb 533 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
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534 from those specified in the SI and IEC 80000-13 standards to provide
535 compatibility with old scripts. For example, 4k means 4096.
536
537 For quantities of data, an optional unit of 'B' may be included
b8f7e412 538 (e.g., 'kB' is the same as 'k').
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539
540 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
541 not milli). 'b' and 'B' both mean byte, not bit.
542
9207a0cb 543 Examples with :option:`kb_base`\=1000:
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544
545 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
546 * *1 MiB*: 1048576, 1mi, 1024ki
547 * *1 MB*: 1000000, 1m, 1000k
548 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
549 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
550
9207a0cb 551 Examples with :option:`kb_base`\=1024 (default):
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552
553 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
554 * *1 MiB*: 1048576, 1m, 1024k
555 * *1 MB*: 1000000, 1mi, 1000ki
556 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
557 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
558
559 To specify times (units are not case sensitive):
560
561 * *D* -- means days
562 * *H* -- means hours
4502cb42 563 * *M* -- means minutes
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564 * *s* -- or sec means seconds (default)
565 * *ms* -- or *msec* means milliseconds
566 * *us* -- or *usec* means microseconds
567
568 If the option accepts an upper and lower range, use a colon ':' or
569 minus '-' to separate such values. See :ref:`irange <irange>`.
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570 If the lower value specified happens to be larger than the upper value
571 the two values are swapped.
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572
573.. _bool:
574
575**bool**
576 Boolean. Usually parsed as an integer, however only defined for
577 true and false (1 and 0).
578
579.. _irange:
580
581**irange**
582 Integer range with suffix. Allows value range to be given, such as
c60ebc45 583 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
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584 option allows two sets of ranges, they can be specified with a ',' or '/'
585 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
586
587**float_list**
588 A list of floating point numbers, separated by a ':' character.
589
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590With the above in mind, here follows the complete list of fio job parameters.
591
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592
593Units
594~~~~~
595
596.. option:: kb_base=int
597
598 Select the interpretation of unit prefixes in input parameters.
599
600 **1000**
601 Inputs comply with IEC 80000-13 and the International
602 System of Units (SI). Use:
603
604 - power-of-2 values with IEC prefixes (e.g., KiB)
605 - power-of-10 values with SI prefixes (e.g., kB)
606
607 **1024**
608 Compatibility mode (default). To avoid breaking old scripts:
609
610 - power-of-2 values with SI prefixes
611 - power-of-10 values with IEC prefixes
612
613 See :option:`bs` for more details on input parameters.
614
615 Outputs always use correct prefixes. Most outputs include both
616 side-by-side, like::
617
618 bw=2383.3kB/s (2327.4KiB/s)
619
620 If only one value is reported, then kb_base selects the one to use:
621
622 **1000** -- SI prefixes
623
624 **1024** -- IEC prefixes
625
626.. option:: unit_base=int
627
628 Base unit for reporting. Allowed values are:
629
630 **0**
631 Use auto-detection (default).
632 **8**
633 Byte based.
634 **1**
635 Bit based.
636
637
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638Job description
639~~~~~~~~~~~~~~~
640
641.. option:: name=str
642
643 ASCII name of the job. This may be used to override the name printed by fio
644 for this job. Otherwise the job name is used. On the command line this
645 parameter has the special purpose of also signaling the start of a new job.
646
647.. option:: description=str
648
649 Text description of the job. Doesn't do anything except dump this text
650 description when this job is run. It's not parsed.
651
652.. option:: loops=int
653
654 Run the specified number of iterations of this job. Used to repeat the same
655 workload a given number of times. Defaults to 1.
656
657.. option:: numjobs=int
658
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659 Create the specified number of clones of this job. Each clone of job
660 is spawned as an independent thread or process. May be used to setup a
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661 larger number of threads/processes doing the same thing. Each thread is
662 reported separately; to see statistics for all clones as a whole, use
663 :option:`group_reporting` in conjunction with :option:`new_group`.
a47b697c 664 See :option:`--max-jobs`. Default: 1.
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665
666
667Time related parameters
668~~~~~~~~~~~~~~~~~~~~~~~
669
670.. option:: runtime=time
671
f75ede1d 672 Tell fio to terminate processing after the specified period of time. It
f80dba8d 673 can be quite hard to determine for how long a specified job will run, so
f75ede1d 674 this parameter is handy to cap the total runtime to a given time. When
804c0839 675 the unit is omitted, the value is interpreted in seconds.
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676
677.. option:: time_based
678
679 If set, fio will run for the duration of the :option:`runtime` specified
680 even if the file(s) are completely read or written. It will simply loop over
681 the same workload as many times as the :option:`runtime` allows.
682
a881438b 683.. option:: startdelay=irange(time)
f80dba8d 684
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685 Delay the start of job for the specified amount of time. Can be a single
686 value or a range. When given as a range, each thread will choose a value
687 randomly from within the range. Value is in seconds if a unit is omitted.
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688
689.. option:: ramp_time=time
690
691 If set, fio will run the specified workload for this amount of time before
692 logging any performance numbers. Useful for letting performance settle
693 before logging results, thus minimizing the runtime required for stable
694 results. Note that the ``ramp_time`` is considered lead in time for a job,
695 thus it will increase the total runtime if a special timeout or
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696 :option:`runtime` is specified. When the unit is omitted, the value is
697 given in seconds.
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698
699.. option:: clocksource=str
700
701 Use the given clocksource as the base of timing. The supported options are:
702
703 **gettimeofday**
704 :manpage:`gettimeofday(2)`
705
706 **clock_gettime**
707 :manpage:`clock_gettime(2)`
708
709 **cpu**
710 Internal CPU clock source
711
712 cpu is the preferred clocksource if it is reliable, as it is very fast (and
713 fio is heavy on time calls). Fio will automatically use this clocksource if
714 it's supported and considered reliable on the system it is running on,
715 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
716 means supporting TSC Invariant.
717
718.. option:: gtod_reduce=bool
719
720 Enable all of the :manpage:`gettimeofday(2)` reducing options
f75ede1d 721 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
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722 reduce precision of the timeout somewhat to really shrink the
723 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
724 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
725 time keeping was enabled.
726
727.. option:: gtod_cpu=int
728
729 Sometimes it's cheaper to dedicate a single thread of execution to just
730 getting the current time. Fio (and databases, for instance) are very
731 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
732 one CPU aside for doing nothing but logging current time to a shared memory
733 location. Then the other threads/processes that run I/O workloads need only
734 copy that segment, instead of entering the kernel with a
735 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
736 calls will be excluded from other uses. Fio will manually clear it from the
737 CPU mask of other jobs.
738
739
740Target file/device
741~~~~~~~~~~~~~~~~~~
742
743.. option:: directory=str
744
745 Prefix filenames with this directory. Used to place files in a different
746 location than :file:`./`. You can specify a number of directories by
747 separating the names with a ':' character. These directories will be
02dd2689 748 assigned equally distributed to job clones created by :option:`numjobs` as
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749 long as they are using generated filenames. If specific `filename(s)` are
750 set fio will use the first listed directory, and thereby matching the
751 `filename` semantic which generates a file each clone if not specified, but
752 let all clones use the same if set.
753
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754 See the :option:`filename` option for information on how to escape "``:``" and
755 "``\``" characters within the directory path itself.
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756
757.. option:: filename=str
758
759 Fio normally makes up a `filename` based on the job name, thread number, and
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760 file number (see :option:`filename_format`). If you want to share files
761 between threads in a job or several
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762 jobs with fixed file paths, specify a `filename` for each of them to override
763 the default. If the ioengine is file based, you can specify a number of files
764 by separating the names with a ':' colon. So if you wanted a job to open
765 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
766 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
767 specified, :option:`nrfiles` is ignored. The size of regular files specified
02dd2689 768 by this option will be :option:`size` divided by number of files unless an
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769 explicit size is specified by :option:`filesize`.
770
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771 Each colon and backslash in the wanted path must be escaped with a ``\``
772 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
773 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
774 :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
775
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776 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
777 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
778 Note: Windows and FreeBSD prevent write access to areas
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779 of the disk containing in-use data (e.g. filesystems).
780
781 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
782 of the two depends on the read/write direction set.
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783
784.. option:: filename_format=str
785
786 If sharing multiple files between jobs, it is usually necessary to have fio
787 generate the exact names that you want. By default, fio will name a file
788 based on the default file format specification of
789 :file:`jobname.jobnumber.filenumber`. With this option, that can be
790 customized. Fio will recognize and replace the following keywords in this
791 string:
792
793 **$jobname**
794 The name of the worker thread or process.
795 **$jobnum**
796 The incremental number of the worker thread or process.
797 **$filenum**
798 The incremental number of the file for that worker thread or
799 process.
800
801 To have dependent jobs share a set of files, this option can be set to have
802 fio generate filenames that are shared between the two. For instance, if
803 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
804 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
805 will be used if no other format specifier is given.
806
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807 If you specify a path then the directories will be created up to the
808 main directory for the file. So for example if you specify
809 ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
810 created before the file setup part of the job. If you specify
811 :option:`directory` then the path will be relative that directory,
812 otherwise it is treated as the absolute path.
813
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814.. option:: unique_filename=bool
815
816 To avoid collisions between networked clients, fio defaults to prefixing any
817 generated filenames (with a directory specified) with the source of the
818 client connecting. To disable this behavior, set this option to 0.
819
820.. option:: opendir=str
821
822 Recursively open any files below directory `str`.
823
824.. option:: lockfile=str
825
826 Fio defaults to not locking any files before it does I/O to them. If a file
827 or file descriptor is shared, fio can serialize I/O to that file to make the
828 end result consistent. This is usual for emulating real workloads that share
829 files. The lock modes are:
830
831 **none**
832 No locking. The default.
833 **exclusive**
834 Only one thread or process may do I/O at a time, excluding all
835 others.
836 **readwrite**
837 Read-write locking on the file. Many readers may
838 access the file at the same time, but writes get exclusive access.
839
840.. option:: nrfiles=int
841
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842 Number of files to use for this job. Defaults to 1. The size of files
843 will be :option:`size` divided by this unless explicit size is specified by
844 :option:`filesize`. Files are created for each thread separately, and each
845 file will have a file number within its name by default, as explained in
846 :option:`filename` section.
847
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848
849.. option:: openfiles=int
850
851 Number of files to keep open at the same time. Defaults to the same as
852 :option:`nrfiles`, can be set smaller to limit the number simultaneous
853 opens.
854
855.. option:: file_service_type=str
856
857 Defines how fio decides which file from a job to service next. The following
858 types are defined:
859
860 **random**
861 Choose a file at random.
862
863 **roundrobin**
864 Round robin over opened files. This is the default.
865
866 **sequential**
867 Finish one file before moving on to the next. Multiple files can
f50fbdda 868 still be open depending on :option:`openfiles`.
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869
870 **zipf**
c60ebc45 871 Use a *Zipf* distribution to decide what file to access.
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872
873 **pareto**
c60ebc45 874 Use a *Pareto* distribution to decide what file to access.
f80dba8d 875
dd3503d3 876 **normal**
c60ebc45 877 Use a *Gaussian* (normal) distribution to decide what file to
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878 access.
879
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880 **gauss**
881 Alias for normal.
882
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883 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
884 tell fio how many I/Os to issue before switching to a new file. For example,
885 specifying ``file_service_type=random:8`` would cause fio to issue
886 8 I/Os before selecting a new file at random. For the non-uniform
887 distributions, a floating point postfix can be given to influence how the
888 distribution is skewed. See :option:`random_distribution` for a description
889 of how that would work.
890
891.. option:: ioscheduler=str
892
893 Attempt to switch the device hosting the file to the specified I/O scheduler
894 before running.
895
896.. option:: create_serialize=bool
897
898 If true, serialize the file creation for the jobs. This may be handy to
899 avoid interleaving of data files, which may greatly depend on the filesystem
a47b697c 900 used and even the number of processors in the system. Default: true.
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901
902.. option:: create_fsync=bool
903
22413915 904 :manpage:`fsync(2)` the data file after creation. This is the default.
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905
906.. option:: create_on_open=bool
907
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908 If true, don't pre-create files but allow the job's open() to create a file
909 when it's time to do I/O. Default: false -- pre-create all necessary files
910 when the job starts.
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911
912.. option:: create_only=bool
913
914 If true, fio will only run the setup phase of the job. If files need to be
4502cb42 915 laid out or updated on disk, only that will be done -- the actual job contents
a47b697c 916 are not executed. Default: false.
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917
918.. option:: allow_file_create=bool
919
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920 If true, fio is permitted to create files as part of its workload. If this
921 option is false, then fio will error out if
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922 the files it needs to use don't already exist. Default: true.
923
924.. option:: allow_mounted_write=bool
925
c60ebc45 926 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
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927 to what appears to be a mounted device or partition. This should help catch
928 creating inadvertently destructive tests, not realizing that the test will
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929 destroy data on the mounted file system. Note that some platforms don't allow
930 writing against a mounted device regardless of this option. Default: false.
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931
932.. option:: pre_read=bool
933
934 If this is given, files will be pre-read into memory before starting the
935 given I/O operation. This will also clear the :option:`invalidate` flag,
936 since it is pointless to pre-read and then drop the cache. This will only
937 work for I/O engines that are seek-able, since they allow you to read the
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938 same data multiple times. Thus it will not work on non-seekable I/O engines
939 (e.g. network, splice). Default: false.
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940
941.. option:: unlink=bool
942
943 Unlink the job files when done. Not the default, as repeated runs of that
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944 job would then waste time recreating the file set again and again. Default:
945 false.
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946
947.. option:: unlink_each_loop=bool
948
a47b697c 949 Unlink job files after each iteration or loop. Default: false.
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950
951.. option:: zonesize=int
952
953 Divide a file into zones of the specified size. See :option:`zoneskip`.
954
955.. option:: zonerange=int
956
957 Give size of an I/O zone. See :option:`zoneskip`.
958
959.. option:: zoneskip=int
960
961 Skip the specified number of bytes when :option:`zonesize` data has been
962 read. The two zone options can be used to only do I/O on zones of a file.
963
964
965I/O type
966~~~~~~~~
967
968.. option:: direct=bool
969
970 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
8e889110 971 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
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972 ioengines don't support direct I/O. Default: false.
973
974.. option:: atomic=bool
975
976 If value is true, attempt to use atomic direct I/O. Atomic writes are
977 guaranteed to be stable once acknowledged by the operating system. Only
978 Linux supports O_ATOMIC right now.
979
980.. option:: buffered=bool
981
982 If value is true, use buffered I/O. This is the opposite of the
983 :option:`direct` option. Defaults to true.
984
985.. option:: readwrite=str, rw=str
986
987 Type of I/O pattern. Accepted values are:
988
989 **read**
990 Sequential reads.
991 **write**
992 Sequential writes.
993 **trim**
994 Sequential trims (Linux block devices only).
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995 **randread**
996 Random reads.
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997 **randwrite**
998 Random writes.
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999 **randtrim**
1000 Random trims (Linux block devices only).
1001 **rw,readwrite**
1002 Sequential mixed reads and writes.
1003 **randrw**
1004 Random mixed reads and writes.
1005 **trimwrite**
1006 Sequential trim+write sequences. Blocks will be trimmed first,
1007 then the same blocks will be written to.
1008
1009 Fio defaults to read if the option is not specified. For the mixed I/O
1010 types, the default is to split them 50/50. For certain types of I/O the
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1011 result may still be skewed a bit, since the speed may be different.
1012
1013 It is possible to specify the number of I/Os to do before getting a new
1014 offset by appending ``:<nr>`` to the end of the string given. For a
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1015 random read, it would look like ``rw=randread:8`` for passing in an offset
1016 modifier with a value of 8. If the suffix is used with a sequential I/O
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1017 pattern, then the *<nr>* value specified will be **added** to the generated
1018 offset for each I/O turning sequential I/O into sequential I/O with holes.
1019 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1020 the :option:`rw_sequencer` option.
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1021
1022.. option:: rw_sequencer=str
1023
1024 If an offset modifier is given by appending a number to the ``rw=<str>``
1025 line, then this option controls how that number modifies the I/O offset
1026 being generated. Accepted values are:
1027
1028 **sequential**
1029 Generate sequential offset.
1030 **identical**
1031 Generate the same offset.
1032
1033 ``sequential`` is only useful for random I/O, where fio would normally
c60ebc45 1034 generate a new random offset for every I/O. If you append e.g. 8 to randread,
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1035 you would get a new random offset for every 8 I/Os. The result would be a
1036 seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
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1037 to specify that. As sequential I/O is already sequential, setting
1038 ``sequential`` for that would not result in any differences. ``identical``
1039 behaves in a similar fashion, except it sends the same offset 8 number of
1040 times before generating a new offset.
1041
1042.. option:: unified_rw_reporting=bool
1043
1044 Fio normally reports statistics on a per data direction basis, meaning that
1045 reads, writes, and trims are accounted and reported separately. If this
1046 option is set fio sums the results and report them as "mixed" instead.
1047
1048.. option:: randrepeat=bool
1049
1050 Seed the random number generator used for random I/O patterns in a
1051 predictable way so the pattern is repeatable across runs. Default: true.
1052
1053.. option:: allrandrepeat=bool
1054
1055 Seed all random number generators in a predictable way so results are
1056 repeatable across runs. Default: false.
1057
1058.. option:: randseed=int
1059
1060 Seed the random number generators based on this seed value, to be able to
1061 control what sequence of output is being generated. If not set, the random
1062 sequence depends on the :option:`randrepeat` setting.
1063
1064.. option:: fallocate=str
1065
1066 Whether pre-allocation is performed when laying down files.
1067 Accepted values are:
1068
1069 **none**
1070 Do not pre-allocate space.
1071
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1072 **native**
1073 Use a platform's native pre-allocation call but fall back to
1074 **none** behavior if it fails/is not implemented.
1075
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1076 **posix**
1077 Pre-allocate via :manpage:`posix_fallocate(3)`.
1078
1079 **keep**
1080 Pre-allocate via :manpage:`fallocate(2)` with
1081 FALLOC_FL_KEEP_SIZE set.
1082
1083 **0**
1084 Backward-compatible alias for **none**.
1085
1086 **1**
1087 Backward-compatible alias for **posix**.
1088
1089 May not be available on all supported platforms. **keep** is only available
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1090 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1091 because ZFS doesn't support pre-allocation. Default: **native** if any
1092 pre-allocation methods are available, **none** if not.
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1093
1094.. option:: fadvise_hint=str
1095
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1096 Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to
1097 advise the kernel on what I/O patterns are likely to be issued.
1098 Accepted values are:
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1099
1100 **0**
1101 Backwards-compatible hint for "no hint".
1102
1103 **1**
1104 Backwards compatible hint for "advise with fio workload type". This
1105 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1106 for a sequential workload.
1107
1108 **sequential**
1109 Advise using **FADV_SEQUENTIAL**.
1110
1111 **random**
1112 Advise using **FADV_RANDOM**.
1113
8f4b9f24 1114.. option:: write_hint=str
f80dba8d 1115
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1116 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1117 from a write. Only supported on Linux, as of version 4.13. Accepted
1118 values are:
1119
1120 **none**
1121 No particular life time associated with this file.
1122
1123 **short**
1124 Data written to this file has a short life time.
1125
1126 **medium**
1127 Data written to this file has a medium life time.
1128
1129 **long**
1130 Data written to this file has a long life time.
1131
1132 **extreme**
1133 Data written to this file has a very long life time.
1134
1135 The values are all relative to each other, and no absolute meaning
1136 should be associated with them.
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1137
1138.. option:: offset=int
1139
82dbb8cb 1140 Start I/O at the provided offset in the file, given as either a fixed size in
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1141 bytes or a percentage. If a percentage is given, the generated offset will be
1142 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1143 provided. Data before the given offset will not be touched. This
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1144 effectively caps the file size at `real_size - offset`. Can be combined with
1145 :option:`size` to constrain the start and end range of the I/O workload.
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1146 A percentage can be specified by a number between 1 and 100 followed by '%',
1147 for example, ``offset=20%`` to specify 20%.
f80dba8d 1148
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1149.. option:: offset_align=int
1150
1151 If set to non-zero value, the byte offset generated by a percentage ``offset``
1152 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1153 offset is aligned to the minimum block size.
1154
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1155.. option:: offset_increment=int
1156
1157 If this is provided, then the real offset becomes `offset + offset_increment
1158 * thread_number`, where the thread number is a counter that starts at 0 and
1159 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1160 specified). This option is useful if there are several jobs which are
1161 intended to operate on a file in parallel disjoint segments, with even
1162 spacing between the starting points.
1163
1164.. option:: number_ios=int
1165
c60ebc45 1166 Fio will normally perform I/Os until it has exhausted the size of the region
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1167 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1168 condition). With this setting, the range/size can be set independently of
c60ebc45 1169 the number of I/Os to perform. When fio reaches this number, it will exit
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1170 normally and report status. Note that this does not extend the amount of I/O
1171 that will be done, it will only stop fio if this condition is met before
1172 other end-of-job criteria.
1173
1174.. option:: fsync=int
1175
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1176 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1177 the dirty data for every number of blocks given. For example, if you give 32
1178 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1179 using non-buffered I/O, we may not sync the file. The exception is the sg
1180 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1181 means fio does not periodically issue and wait for a sync to complete. Also
1182 see :option:`end_fsync` and :option:`fsync_on_close`.
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1183
1184.. option:: fdatasync=int
1185
1186 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
000a5f1c 1187 not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
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1188 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1189 Defaults to 0, which means fio does not periodically issue and wait for a
1190 data-only sync to complete.
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1191
1192.. option:: write_barrier=int
1193
2831be97 1194 Make every `N-th` write a barrier write.
f80dba8d 1195
f50fbdda 1196.. option:: sync_file_range=str:int
f80dba8d 1197
f50fbdda 1198 Use :manpage:`sync_file_range(2)` for every `int` number of write
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1199 operations. Fio will track range of writes that have happened since the last
1200 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1201
1202 **wait_before**
1203 SYNC_FILE_RANGE_WAIT_BEFORE
1204 **write**
1205 SYNC_FILE_RANGE_WRITE
1206 **wait_after**
1207 SYNC_FILE_RANGE_WAIT_AFTER
1208
1209 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1210 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1211 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1212 Linux specific.
1213
1214.. option:: overwrite=bool
1215
1216 If true, writes to a file will always overwrite existing data. If the file
1217 doesn't already exist, it will be created before the write phase begins. If
1218 the file exists and is large enough for the specified write phase, nothing
a47b697c 1219 will be done. Default: false.
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1220
1221.. option:: end_fsync=bool
1222
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1223 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1224 Default: false.
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1225
1226.. option:: fsync_on_close=bool
1227
1228 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
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1229 from :option:`end_fsync` in that it will happen on every file close, not
1230 just at the end of the job. Default: false.
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1231
1232.. option:: rwmixread=int
1233
1234 Percentage of a mixed workload that should be reads. Default: 50.
1235
1236.. option:: rwmixwrite=int
1237
1238 Percentage of a mixed workload that should be writes. If both
1239 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1240 add up to 100%, the latter of the two will be used to override the
1241 first. This may interfere with a given rate setting, if fio is asked to
1242 limit reads or writes to a certain rate. If that is the case, then the
1243 distribution may be skewed. Default: 50.
1244
1245.. option:: random_distribution=str:float[,str:float][,str:float]
1246
1247 By default, fio will use a completely uniform random distribution when asked
1248 to perform random I/O. Sometimes it is useful to skew the distribution in
1249 specific ways, ensuring that some parts of the data is more hot than others.
1250 fio includes the following distribution models:
1251
1252 **random**
1253 Uniform random distribution
1254
1255 **zipf**
1256 Zipf distribution
1257
1258 **pareto**
1259 Pareto distribution
1260
b2f4b559 1261 **normal**
c60ebc45 1262 Normal (Gaussian) distribution
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1263
1264 **zoned**
1265 Zoned random distribution
1266
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1267 **zoned_abs**
1268 Zone absolute random distribution
1269
f80dba8d 1270 When using a **zipf** or **pareto** distribution, an input value is also
f50fbdda 1271 needed to define the access pattern. For **zipf**, this is the `Zipf
c60ebc45 1272 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
f50fbdda 1273 program, :command:`fio-genzipf`, that can be used visualize what the given input
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1274 values will yield in terms of hit rates. If you wanted to use **zipf** with
1275 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1276 option. If a non-uniform model is used, fio will disable use of the random
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1277 map. For the **normal** distribution, a normal (Gaussian) deviation is
1278 supplied as a value between 0 and 100.
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1279
1280 For a **zoned** distribution, fio supports specifying percentages of I/O
1281 access that should fall within what range of the file or device. For
1282 example, given a criteria of:
1283
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1284 * 60% of accesses should be to the first 10%
1285 * 30% of accesses should be to the next 20%
1286 * 8% of accesses should be to the next 30%
1287 * 2% of accesses should be to the next 40%
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1288
1289 we can define that through zoning of the random accesses. For the above
1290 example, the user would do::
1291
1292 random_distribution=zoned:60/10:30/20:8/30:2/40
1293
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1294 A **zoned_abs** distribution works exactly like the **zoned**, except
1295 that it takes absolute sizes. For example, let's say you wanted to
1296 define access according to the following criteria:
1297
1298 * 60% of accesses should be to the first 20G
1299 * 30% of accesses should be to the next 100G
1300 * 10% of accesses should be to the next 500G
1301
1302 we can define an absolute zoning distribution with:
1303
1304 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1305
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1306 For both **zoned** and **zoned_abs**, fio supports defining up to
1307 256 separate zones.
1308
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1309 Similarly to how :option:`bssplit` works for setting ranges and
1310 percentages of block sizes. Like :option:`bssplit`, it's possible to
1311 specify separate zones for reads, writes, and trims. If just one set
1312 is given, it'll apply to all of them. This goes for both **zoned**
1313 **zoned_abs** distributions.
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1314
1315.. option:: percentage_random=int[,int][,int]
1316
1317 For a random workload, set how big a percentage should be random. This
1318 defaults to 100%, in which case the workload is fully random. It can be set
1319 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1320 sequential. Any setting in between will result in a random mix of sequential
1321 and random I/O, at the given percentages. Comma-separated values may be
1322 specified for reads, writes, and trims as described in :option:`blocksize`.
1323
1324.. option:: norandommap
1325
1326 Normally fio will cover every block of the file when doing random I/O. If
1327 this option is given, fio will just get a new random offset without looking
1328 at past I/O history. This means that some blocks may not be read or written,
1329 and that some blocks may be read/written more than once. If this option is
1330 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1331 only intact blocks are verified, i.e., partially-overwritten blocks are
1332 ignored.
1333
1334.. option:: softrandommap=bool
1335
1336 See :option:`norandommap`. If fio runs with the random block map enabled and
1337 it fails to allocate the map, if this option is set it will continue without
1338 a random block map. As coverage will not be as complete as with random maps,
1339 this option is disabled by default.
1340
1341.. option:: random_generator=str
1342
f50fbdda 1343 Fio supports the following engines for generating I/O offsets for random I/O:
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1344
1345 **tausworthe**
f50fbdda 1346 Strong 2^88 cycle random number generator.
f80dba8d 1347 **lfsr**
f50fbdda 1348 Linear feedback shift register generator.
f80dba8d 1349 **tausworthe64**
f50fbdda 1350 Strong 64-bit 2^258 cycle random number generator.
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1351
1352 **tausworthe** is a strong random number generator, but it requires tracking
1353 on the side if we want to ensure that blocks are only read or written
f50fbdda 1354 once. **lfsr** guarantees that we never generate the same offset twice, and
f80dba8d 1355 it's also less computationally expensive. It's not a true random generator,
f50fbdda 1356 however, though for I/O purposes it's typically good enough. **lfsr** only
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1357 works with single block sizes, not with workloads that use multiple block
1358 sizes. If used with such a workload, fio may read or write some blocks
1359 multiple times. The default value is **tausworthe**, unless the required
1360 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1361 selected automatically.
1362
1363
1364Block size
1365~~~~~~~~~~
1366
1367.. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1368
1369 The block size in bytes used for I/O units. Default: 4096. A single value
1370 applies to reads, writes, and trims. Comma-separated values may be
1371 specified for reads, writes, and trims. A value not terminated in a comma
1372 applies to subsequent types.
1373
1374 Examples:
1375
1376 **bs=256k**
1377 means 256k for reads, writes and trims.
1378
1379 **bs=8k,32k**
1380 means 8k for reads, 32k for writes and trims.
1381
1382 **bs=8k,32k,**
1383 means 8k for reads, 32k for writes, and default for trims.
1384
1385 **bs=,8k**
1386 means default for reads, 8k for writes and trims.
1387
1388 **bs=,8k,**
b443ae44 1389 means default for reads, 8k for writes, and default for trims.
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1390
1391.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1392
1393 A range of block sizes in bytes for I/O units. The issued I/O unit will
1394 always be a multiple of the minimum size, unless
1395 :option:`blocksize_unaligned` is set.
1396
1397 Comma-separated ranges may be specified for reads, writes, and trims as
1398 described in :option:`blocksize`.
1399
1400 Example: ``bsrange=1k-4k,2k-8k``.
1401
1402.. option:: bssplit=str[,str][,str]
1403
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1404 Sometimes you want even finer grained control of the block sizes
1405 issued, not just an even split between them. This option allows you to
1406 weight various block sizes, so that you are able to define a specific
1407 amount of block sizes issued. The format for this option is::
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1408
1409 bssplit=blocksize/percentage:blocksize/percentage
1410
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1411 for as many block sizes as needed. So if you want to define a workload
1412 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1413 write::
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1414
1415 bssplit=4k/10:64k/50:32k/40
1416
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1417 Ordering does not matter. If the percentage is left blank, fio will
1418 fill in the remaining values evenly. So a bssplit option like this one::
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1419
1420 bssplit=4k/50:1k/:32k/
1421
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1422 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1423 add up to 100, if bssplit is given a range that adds up to more, it
1424 will error out.
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1425
1426 Comma-separated values may be specified for reads, writes, and trims as
1427 described in :option:`blocksize`.
1428
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1429 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1430 having 90% 4k writes and 10% 8k writes, you would specify::
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1431
1432 bssplit=2k/50:4k/50,4k/90,8k/10
1433
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1434 Fio supports defining up to 64 different weights for each data
1435 direction.
1436
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1437.. option:: blocksize_unaligned, bs_unaligned
1438
1439 If set, fio will issue I/O units with any size within
1440 :option:`blocksize_range`, not just multiples of the minimum size. This
1441 typically won't work with direct I/O, as that normally requires sector
1442 alignment.
1443
589e88b7 1444.. option:: bs_is_seq_rand=bool
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1445
1446 If this option is set, fio will use the normal read,write blocksize settings
1447 as sequential,random blocksize settings instead. Any random read or write
1448 will use the WRITE blocksize settings, and any sequential read or write will
1449 use the READ blocksize settings.
1450
1451.. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1452
1453 Boundary to which fio will align random I/O units. Default:
1454 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1455 I/O, though it usually depends on the hardware block size. This option is
1456 mutually exclusive with using a random map for files, so it will turn off
1457 that option. Comma-separated values may be specified for reads, writes, and
1458 trims as described in :option:`blocksize`.
1459
1460
1461Buffers and memory
1462~~~~~~~~~~~~~~~~~~
1463
1464.. option:: zero_buffers
1465
1466 Initialize buffers with all zeros. Default: fill buffers with random data.
1467
1468.. option:: refill_buffers
1469
1470 If this option is given, fio will refill the I/O buffers on every
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1471 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1472 naturally. Defaults to being unset i.e., the buffer is only filled at
1473 init time and the data in it is reused when possible but if any of
1474 :option:`verify`, :option:`buffer_compress_percentage` or
1475 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1476 automatically enabled.
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1477
1478.. option:: scramble_buffers=bool
1479
1480 If :option:`refill_buffers` is too costly and the target is using data
1481 deduplication, then setting this option will slightly modify the I/O buffer
1482 contents to defeat normal de-dupe attempts. This is not enough to defeat
1483 more clever block compression attempts, but it will stop naive dedupe of
1484 blocks. Default: true.
1485
1486.. option:: buffer_compress_percentage=int
1487
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1488 If this is set, then fio will attempt to provide I/O buffer content
1489 (on WRITEs) that compresses to the specified level. Fio does this by
1490 providing a mix of random data followed by fixed pattern data. The
1491 fixed pattern is either zeros, or the pattern specified by
1492 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1493 might skew the compression ratio slightly. Setting
1494 `buffer_compress_percentage` to a value other than 100 will also
1495 enable :option:`refill_buffers` in order to reduce the likelihood that
1496 adjacent blocks are so similar that they over compress when seen
1497 together. See :option:`buffer_compress_chunk` for how to set a finer or
1498 coarser granularity for the random/fixed data region. Defaults to unset
1499 i.e., buffer data will not adhere to any compression level.
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1500
1501.. option:: buffer_compress_chunk=int
1502
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1503 This setting allows fio to manage how big the random/fixed data region
1504 is when using :option:`buffer_compress_percentage`. When
1505 `buffer_compress_chunk` is set to some non-zero value smaller than the
1506 block size, fio can repeat the random/fixed region throughout the I/O
1507 buffer at the specified interval (which particularly useful when
1508 bigger block sizes are used for a job). When set to 0, fio will use a
1509 chunk size that matches the block size resulting in a single
1510 random/fixed region within the I/O buffer. Defaults to 512. When the
1511 unit is omitted, the value is interpreted in bytes.
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1512
1513.. option:: buffer_pattern=str
1514
a1554f65
SB
1515 If set, fio will fill the I/O buffers with this pattern or with the contents
1516 of a file. If not set, the contents of I/O buffers are defined by the other
1517 options related to buffer contents. The setting can be any pattern of bytes,
1518 and can be prefixed with 0x for hex values. It may also be a string, where
1519 the string must then be wrapped with ``""``. Or it may also be a filename,
1520 where the filename must be wrapped with ``''`` in which case the file is
1521 opened and read. Note that not all the file contents will be read if that
1522 would cause the buffers to overflow. So, for example::
1523
1524 buffer_pattern='filename'
1525
1526 or::
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1527
1528 buffer_pattern="abcd"
1529
1530 or::
1531
1532 buffer_pattern=-12
1533
1534 or::
1535
1536 buffer_pattern=0xdeadface
1537
1538 Also you can combine everything together in any order::
1539
a1554f65 1540 buffer_pattern=0xdeadface"abcd"-12'filename'
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1541
1542.. option:: dedupe_percentage=int
1543
1544 If set, fio will generate this percentage of identical buffers when
1545 writing. These buffers will be naturally dedupable. The contents of the
1546 buffers depend on what other buffer compression settings have been set. It's
1547 possible to have the individual buffers either fully compressible, or not at
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1548 all -- this option only controls the distribution of unique buffers. Setting
1549 this option will also enable :option:`refill_buffers` to prevent every buffer
1550 being identical.
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1551
1552.. option:: invalidate=bool
1553
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1554 Invalidate the buffer/page cache parts of the files to be used prior to
1555 starting I/O if the platform and file type support it. Defaults to true.
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1556 This will be ignored if :option:`pre_read` is also specified for the
1557 same job.
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1558
1559.. option:: sync=bool
1560
1561 Use synchronous I/O for buffered writes. For the majority of I/O engines,
1562 this means using O_SYNC. Default: false.
1563
1564.. option:: iomem=str, mem=str
1565
1566 Fio can use various types of memory as the I/O unit buffer. The allowed
1567 values are:
1568
1569 **malloc**
1570 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1571 type.
1572
1573 **shm**
1574 Use shared memory as the buffers. Allocated through
1575 :manpage:`shmget(2)`.
1576
1577 **shmhuge**
1578 Same as shm, but use huge pages as backing.
1579
1580 **mmap**
22413915 1581 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
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1582 be file backed if a filename is given after the option. The format
1583 is `mem=mmap:/path/to/file`.
1584
1585 **mmaphuge**
1586 Use a memory mapped huge file as the buffer backing. Append filename
1587 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1588
1589 **mmapshared**
1590 Same as mmap, but use a MMAP_SHARED mapping.
1591
03553853
YR
1592 **cudamalloc**
1593 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
f50fbdda 1594 The :option:`ioengine` must be `rdma`.
03553853 1595
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1596 The area allocated is a function of the maximum allowed bs size for the job,
1597 multiplied by the I/O depth given. Note that for **shmhuge** and
1598 **mmaphuge** to work, the system must have free huge pages allocated. This
1599 can normally be checked and set by reading/writing
1600 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1601 is 4MiB in size. So to calculate the number of huge pages you need for a
1602 given job file, add up the I/O depth of all jobs (normally one unless
1603 :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
1604 that number by the huge page size. You can see the size of the huge pages in
1605 :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
1606 number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
1607 see :option:`hugepage-size`.
1608
1609 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1610 should point there. So if it's mounted in :file:`/huge`, you would use
1611 `mem=mmaphuge:/huge/somefile`.
1612
f50fbdda 1613.. option:: iomem_align=int, mem_align=int
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1614
1615 This indicates the memory alignment of the I/O memory buffers. Note that
1616 the given alignment is applied to the first I/O unit buffer, if using
1617 :option:`iodepth` the alignment of the following buffers are given by the
1618 :option:`bs` used. In other words, if using a :option:`bs` that is a
1619 multiple of the page sized in the system, all buffers will be aligned to
1620 this value. If using a :option:`bs` that is not page aligned, the alignment
1621 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1622 :option:`bs` used.
1623
1624.. option:: hugepage-size=int
1625
1626 Defines the size of a huge page. Must at least be equal to the system
1627 setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
1628 always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
1629 preferred way to set this to avoid setting a non-pow-2 bad value.
1630
1631.. option:: lockmem=int
1632
1633 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1634 simulate a smaller amount of memory. The amount specified is per worker.
1635
1636
1637I/O size
1638~~~~~~~~
1639
1640.. option:: size=int
1641
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1642 The total size of file I/O for each thread of this job. Fio will run until
1643 this many bytes has been transferred, unless runtime is limited by other options
1644 (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
1645 Fio will divide this size between the available files determined by options
1646 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1647 specified by the job. If the result of division happens to be 0, the size is
c4aa2d08 1648 set to the physical size of the given files or devices if they exist.
79591fa9 1649 If this option is not specified, fio will use the full size of the given
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1650 files or devices. If the files do not exist, size must be given. It is also
1651 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1652 given, fio will use 20% of the full size of the given files or devices.
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1653 Can be combined with :option:`offset` to constrain the start and end range
1654 that I/O will be done within.
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1655
1656.. option:: io_size=int, io_limit=int
1657
1658 Normally fio operates within the region set by :option:`size`, which means
1659 that the :option:`size` option sets both the region and size of I/O to be
1660 performed. Sometimes that is not what you want. With this option, it is
1661 possible to define just the amount of I/O that fio should do. For instance,
1662 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1663 will perform I/O within the first 20GiB but exit when 5GiB have been
1664 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1665 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1666 the 0..20GiB region.
1667
7fdd97ca 1668.. option:: filesize=irange(int)
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1669
1670 Individual file sizes. May be a range, in which case fio will select sizes
1671 for files at random within the given range and limited to :option:`size` in
1672 total (if that is given). If not given, each created file is the same size.
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1673 This option overrides :option:`size` in terms of file size, which means
1674 this value is used as a fixed size or possible range of each file.
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1675
1676.. option:: file_append=bool
1677
1678 Perform I/O after the end of the file. Normally fio will operate within the
1679 size of a file. If this option is set, then fio will append to the file
1680 instead. This has identical behavior to setting :option:`offset` to the size
1681 of a file. This option is ignored on non-regular files.
1682
1683.. option:: fill_device=bool, fill_fs=bool
1684
1685 Sets size to something really large and waits for ENOSPC (no space left on
1686 device) as the terminating condition. Only makes sense with sequential
1687 write. For a read workload, the mount point will be filled first then I/O
1688 started on the result. This option doesn't make sense if operating on a raw
1689 device node, since the size of that is already known by the file system.
1690 Additionally, writing beyond end-of-device will not return ENOSPC there.
1691
1692
1693I/O engine
1694~~~~~~~~~~
1695
1696.. option:: ioengine=str
1697
1698 Defines how the job issues I/O to the file. The following types are defined:
1699
1700 **sync**
1701 Basic :manpage:`read(2)` or :manpage:`write(2)`
1702 I/O. :manpage:`lseek(2)` is used to position the I/O location.
54227e6b 1703 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
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1704
1705 **psync**
1706 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1707 all supported operating systems except for Windows.
1708
1709 **vsync**
1710 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
c60ebc45 1711 queuing by coalescing adjacent I/Os into a single submission.
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1712
1713 **pvsync**
1714 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1715
1716 **pvsync2**
1717 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1718
1719 **libaio**
1720 Linux native asynchronous I/O. Note that Linux may only support
22413915 1721 queued behavior with non-buffered I/O (set ``direct=1`` or
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1722 ``buffered=0``).
1723 This engine defines engine specific options.
1724
1725 **posixaio**
1726 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
1727 :manpage:`aio_write(3)`.
1728
1729 **solarisaio**
1730 Solaris native asynchronous I/O.
1731
1732 **windowsaio**
1733 Windows native asynchronous I/O. Default on Windows.
1734
1735 **mmap**
1736 File is memory mapped with :manpage:`mmap(2)` and data copied
1737 to/from using :manpage:`memcpy(3)`.
1738
1739 **splice**
1740 :manpage:`splice(2)` is used to transfer the data and
1741 :manpage:`vmsplice(2)` to transfer data from user space to the
1742 kernel.
1743
1744 **sg**
1745 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
1746 ioctl, or if the target is an sg character device we use
1747 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
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1748 I/O. Requires :option:`filename` option to specify either block or
1749 character devices.
52b81b7c 1750 The sg engine includes engine specific options.
f80dba8d
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1751
1752 **null**
1753 Doesn't transfer any data, just pretends to. This is mainly used to
1754 exercise fio itself and for debugging/testing purposes.
1755
1756 **net**
1757 Transfer over the network to given ``host:port``. Depending on the
1758 :option:`protocol` used, the :option:`hostname`, :option:`port`,
1759 :option:`listen` and :option:`filename` options are used to specify
1760 what sort of connection to make, while the :option:`protocol` option
1761 determines which protocol will be used. This engine defines engine
1762 specific options.
1763
1764 **netsplice**
1765 Like **net**, but uses :manpage:`splice(2)` and
1766 :manpage:`vmsplice(2)` to map data and send/receive.
1767 This engine defines engine specific options.
1768
1769 **cpuio**
1770 Doesn't transfer any data, but burns CPU cycles according to the
1771 :option:`cpuload` and :option:`cpuchunks` options. Setting
9207a0cb 1772 :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
71aa48eb 1773 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
f50fbdda 1774 to get desired CPU usage, as the cpuload only loads a
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1775 single CPU at the desired rate. A job never finishes unless there is
1776 at least one non-cpuio job.
1777
1778 **guasi**
804c0839 1779 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall
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1780 Interface approach to async I/O. See
1781
1782 http://www.xmailserver.org/guasi-lib.html
1783
1784 for more info on GUASI.
1785
1786 **rdma**
1787 The RDMA I/O engine supports both RDMA memory semantics
1788 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
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1789 InfiniBand, RoCE and iWARP protocols. This engine defines engine
1790 specific options.
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1791
1792 **falloc**
1793 I/O engine that does regular fallocate to simulate data transfer as
1794 fio ioengine.
1795
1796 DDIR_READ
1797 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
1798
1799 DDIR_WRITE
1800 does fallocate(,mode = 0).
1801
1802 DDIR_TRIM
1803 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
1804
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1805 **ftruncate**
1806 I/O engine that sends :manpage:`ftruncate(2)` operations in response
1807 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
f50fbdda 1808 size to the current block offset. :option:`blocksize` is ignored.
761cd093 1809
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1810 **e4defrag**
1811 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
1812 defragment activity in request to DDIR_WRITE event.
1813
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1814 **rados**
1815 I/O engine supporting direct access to Ceph Reliable Autonomic
1816 Distributed Object Store (RADOS) via librados. This ioengine
1817 defines engine specific options.
1818
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1819 **rbd**
1820 I/O engine supporting direct access to Ceph Rados Block Devices
1821 (RBD) via librbd without the need to use the kernel rbd driver. This
1822 ioengine defines engine specific options.
1823
1824 **gfapi**
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1825 Using GlusterFS libgfapi sync interface to direct access to
1826 GlusterFS volumes without having to go through FUSE. This ioengine
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1827 defines engine specific options.
1828
1829 **gfapi_async**
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1830 Using GlusterFS libgfapi async interface to direct access to
1831 GlusterFS volumes without having to go through FUSE. This ioengine
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1832 defines engine specific options.
1833
1834 **libhdfs**
f50fbdda 1835 Read and write through Hadoop (HDFS). The :option:`filename` option
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1836 is used to specify host,port of the hdfs name-node to connect. This
1837 engine interprets offsets a little differently. In HDFS, files once
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1838 created cannot be modified so random writes are not possible. To
1839 imitate this the libhdfs engine expects a bunch of small files to be
1840 created over HDFS and will randomly pick a file from them
1841 based on the offset generated by fio backend (see the example
f80dba8d 1842 job file to create such files, use ``rw=write`` option). Please
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1843 note, it may be necessary to set environment variables to work
1844 with HDFS/libhdfs properly. Each job uses its own connection to
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1845 HDFS.
1846
1847 **mtd**
1848 Read, write and erase an MTD character device (e.g.,
1849 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
1850 underlying device type, the I/O may have to go in a certain pattern,
1851 e.g., on NAND, writing sequentially to erase blocks and discarding
c298ee71 1852 before overwriting. The `trimwrite` mode works well for this
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1853 constraint.
1854
1855 **pmemblk**
1856 Read and write using filesystem DAX to a file on a filesystem
363a5f65 1857 mounted with DAX on a persistent memory device through the PMDK
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1858 libpmemblk library.
1859
1860 **dev-dax**
1861 Read and write using device DAX to a persistent memory device (e.g.,
363a5f65 1862 /dev/dax0.0) through the PMDK libpmem library.
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1863
1864 **external**
1865 Prefix to specify loading an external I/O engine object file. Append
c60ebc45 1866 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
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1867 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
1868 absolute or relative. See :file:`engines/skeleton_external.c` for
1869 details of writing an external I/O engine.
f80dba8d 1870
1216cc5a 1871 **filecreate**
b71968b1 1872 Simply create the files and do no I/O to them. You still need to
1216cc5a 1873 set `filesize` so that all the accounting still occurs, but no
b71968b1 1874 actual I/O will be done other than creating the file.
f80dba8d 1875
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1876 **libpmem**
1877 Read and write using mmap I/O to a file on a filesystem
363a5f65 1878 mounted with DAX on a persistent memory device through the PMDK
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1879 libpmem library.
1880
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1881I/O engine specific parameters
1882~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1883
1884In addition, there are some parameters which are only valid when a specific
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1885:option:`ioengine` is in use. These are used identically to normal parameters,
1886with the caveat that when used on the command line, they must come after the
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1887:option:`ioengine` that defines them is selected.
1888
1889.. option:: userspace_reap : [libaio]
1890
1891 Normally, with the libaio engine in use, fio will use the
1892 :manpage:`io_getevents(2)` system call to reap newly returned events. With
1893 this flag turned on, the AIO ring will be read directly from user-space to
1894 reap events. The reaping mode is only enabled when polling for a minimum of
c60ebc45 1895 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
f80dba8d 1896
9d25d068 1897.. option:: hipri : [pvsync2]
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1898
1899 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
1900 than normal.
1901
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1902.. option:: hipri_percentage : [pvsync2]
1903
f50fbdda 1904 When hipri is set this determines the probability of a pvsync2 I/O being high
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1905 priority. The default is 100%.
1906
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1907.. option:: cpuload=int : [cpuio]
1908
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1909 Attempt to use the specified percentage of CPU cycles. This is a mandatory
1910 option when using cpuio I/O engine.
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1911
1912.. option:: cpuchunks=int : [cpuio]
1913
1914 Split the load into cycles of the given time. In microseconds.
1915
1916.. option:: exit_on_io_done=bool : [cpuio]
1917
1918 Detect when I/O threads are done, then exit.
1919
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1920.. option:: namenode=str : [libhdfs]
1921
22413915 1922 The hostname or IP address of a HDFS cluster namenode to contact.
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1923
1924.. option:: port=int
1925
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1926 [libhdfs]
1927
1928 The listening port of the HFDS cluster namenode.
1929
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1930 [netsplice], [net]
1931
1932 The TCP or UDP port to bind to or connect to. If this is used with
1933 :option:`numjobs` to spawn multiple instances of the same job type, then
1934 this will be the starting port number since fio will use a range of
1935 ports.
1936
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1937 [rdma]
1938
1939 The port to use for RDMA-CM communication. This should be the same value
1940 on the client and the server side.
1941
1942.. option:: hostname=str : [netsplice] [net] [rdma]
f80dba8d 1943
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1944 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
1945 is a TCP listener or UDP reader, the hostname is not used and must be omitted
f50fbdda 1946 unless it is a valid UDP multicast address.
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1947
1948.. option:: interface=str : [netsplice] [net]
1949
1950 The IP address of the network interface used to send or receive UDP
1951 multicast.
1952
1953.. option:: ttl=int : [netsplice] [net]
1954
1955 Time-to-live value for outgoing UDP multicast packets. Default: 1.
1956
1957.. option:: nodelay=bool : [netsplice] [net]
1958
1959 Set TCP_NODELAY on TCP connections.
1960
f50fbdda 1961.. option:: protocol=str, proto=str : [netsplice] [net]
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1962
1963 The network protocol to use. Accepted values are:
1964
1965 **tcp**
1966 Transmission control protocol.
1967 **tcpv6**
1968 Transmission control protocol V6.
1969 **udp**
1970 User datagram protocol.
1971 **udpv6**
1972 User datagram protocol V6.
1973 **unix**
1974 UNIX domain socket.
1975
1976 When the protocol is TCP or UDP, the port must also be given, as well as the
1977 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
f50fbdda 1978 normal :option:`filename` option should be used and the port is invalid.
f80dba8d 1979
e9184ec1 1980.. option:: listen : [netsplice] [net]
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1981
1982 For TCP network connections, tell fio to listen for incoming connections
1983 rather than initiating an outgoing connection. The :option:`hostname` must
1984 be omitted if this option is used.
1985
e9184ec1 1986.. option:: pingpong : [netsplice] [net]
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1987
1988 Normally a network writer will just continue writing data, and a network
1989 reader will just consume packages. If ``pingpong=1`` is set, a writer will
1990 send its normal payload to the reader, then wait for the reader to send the
1991 same payload back. This allows fio to measure network latencies. The
1992 submission and completion latencies then measure local time spent sending or
1993 receiving, and the completion latency measures how long it took for the
1994 other end to receive and send back. For UDP multicast traffic
1995 ``pingpong=1`` should only be set for a single reader when multiple readers
1996 are listening to the same address.
1997
e9184ec1 1998.. option:: window_size : [netsplice] [net]
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1999
2000 Set the desired socket buffer size for the connection.
2001
e9184ec1 2002.. option:: mss : [netsplice] [net]
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2003
2004 Set the TCP maximum segment size (TCP_MAXSEG).
2005
2006.. option:: donorname=str : [e4defrag]
2007
730bd7d9 2008 File will be used as a block donor (swap extents between files).
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2009
2010.. option:: inplace=int : [e4defrag]
2011
2012 Configure donor file blocks allocation strategy:
2013
2014 **0**
2015 Default. Preallocate donor's file on init.
2016 **1**
2b455dbf 2017 Allocate space immediately inside defragment event, and free right
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2018 after event.
2019
f3f96717 2020.. option:: clustername=str : [rbd,rados]
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2021
2022 Specifies the name of the Ceph cluster.
2023
2024.. option:: rbdname=str : [rbd]
2025
2026 Specifies the name of the RBD.
2027
f3f96717 2028.. option:: pool=str : [rbd,rados]
f80dba8d 2029
f3f96717 2030 Specifies the name of the Ceph pool containing RBD or RADOS data.
f80dba8d 2031
f3f96717 2032.. option:: clientname=str : [rbd,rados]
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2033
2034 Specifies the username (without the 'client.' prefix) used to access the
2035 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2036 the full *type.id* string. If no type. prefix is given, fio will add
2037 'client.' by default.
2038
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2039.. option:: busy_poll=bool : [rbd,rados]
2040
2041 Poll store instead of waiting for completion. Usually this provides better
2042 throughput at cost of higher(up to 100%) CPU utilization.
2043
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2044.. option:: skip_bad=bool : [mtd]
2045
2046 Skip operations against known bad blocks.
2047
2048.. option:: hdfsdirectory : [libhdfs]
2049
2050 libhdfs will create chunk in this HDFS directory.
2051
2052.. option:: chunk_size : [libhdfs]
2053
2b455dbf 2054 The size of the chunk to use for each file.
f80dba8d 2055
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2056.. option:: verb=str : [rdma]
2057
2058 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2059 values are write, read, send and recv. These correspond to the equivalent
2060 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2061 specified on the client side of the connection. See the examples folder.
2062
2063.. option:: bindname=str : [rdma]
2064
2065 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2066 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2067 will be passed into the rdma_bind_addr() function and on the client site it
2068 will be used in the rdma_resolve_add() function. This can be useful when
2069 multiple paths exist between the client and the server or in certain loopback
2070 configurations.
f80dba8d 2071
52b81b7c
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2072.. option:: readfua=bool : [sg]
2073
2074 With readfua option set to 1, read operations include
2075 the force unit access (fua) flag. Default is 0.
2076
2077.. option:: writefua=bool : [sg]
2078
2079 With writefua option set to 1, write operations include
2080 the force unit access (fua) flag. Default is 0.
2081
2082
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2083I/O depth
2084~~~~~~~~~
2085
2086.. option:: iodepth=int
2087
2088 Number of I/O units to keep in flight against the file. Note that
2089 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
c60ebc45 2090 for small degrees when :option:`verify_async` is in use). Even async
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2091 engines may impose OS restrictions causing the desired depth not to be
2092 achieved. This may happen on Linux when using libaio and not setting
9207a0cb 2093 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
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2094 eye on the I/O depth distribution in the fio output to verify that the
2095 achieved depth is as expected. Default: 1.
2096
2097.. option:: iodepth_batch_submit=int, iodepth_batch=int
2098
2099 This defines how many pieces of I/O to submit at once. It defaults to 1
2100 which means that we submit each I/O as soon as it is available, but can be
2101 raised to submit bigger batches of I/O at the time. If it is set to 0 the
2102 :option:`iodepth` value will be used.
2103
2104.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
2105
2106 This defines how many pieces of I/O to retrieve at once. It defaults to 1
2107 which means that we'll ask for a minimum of 1 I/O in the retrieval process
2108 from the kernel. The I/O retrieval will go on until we hit the limit set by
2109 :option:`iodepth_low`. If this variable is set to 0, then fio will always
2110 check for completed events before queuing more I/O. This helps reduce I/O
2111 latency, at the cost of more retrieval system calls.
2112
2113.. option:: iodepth_batch_complete_max=int
2114
2115 This defines maximum pieces of I/O to retrieve at once. This variable should
9207a0cb 2116 be used along with :option:`iodepth_batch_complete_min`\=int variable,
f80dba8d 2117 specifying the range of min and max amount of I/O which should be
730bd7d9 2118 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
f80dba8d
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2119 value.
2120
2121 Example #1::
2122
2123 iodepth_batch_complete_min=1
2124 iodepth_batch_complete_max=<iodepth>
2125
2126 which means that we will retrieve at least 1 I/O and up to the whole
2127 submitted queue depth. If none of I/O has been completed yet, we will wait.
2128
2129 Example #2::
2130
2131 iodepth_batch_complete_min=0
2132 iodepth_batch_complete_max=<iodepth>
2133
2134 which means that we can retrieve up to the whole submitted queue depth, but
2135 if none of I/O has been completed yet, we will NOT wait and immediately exit
2136 the system call. In this example we simply do polling.
2137
2138.. option:: iodepth_low=int
2139
2140 The low water mark indicating when to start filling the queue
2141 again. Defaults to the same as :option:`iodepth`, meaning that fio will
2142 attempt to keep the queue full at all times. If :option:`iodepth` is set to
c60ebc45 2143 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
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2144 16 requests, it will let the depth drain down to 4 before starting to fill
2145 it again.
2146
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2147.. option:: serialize_overlap=bool
2148
2149 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
2150 When two or more I/Os are submitted simultaneously, there is no guarantee that
2151 the I/Os will be processed or completed in the submitted order. Further, if
2152 two or more of those I/Os are writes, any overlapping region between them can
2153 become indeterminate/undefined on certain storage. These issues can cause
2154 verification to fail erratically when at least one of the racing I/Os is
2155 changing data and the overlapping region has a non-zero size. Setting
2156 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
2157 serializing in-flight I/Os that have a non-zero overlap. Note that setting
ee21ebee 2158 this option can reduce both performance and the :option:`iodepth` achieved.
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2159 Additionally this option does not work when :option:`io_submit_mode` is set to
2160 offload. Default: false.
2161
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2162.. option:: io_submit_mode=str
2163
2164 This option controls how fio submits the I/O to the I/O engine. The default
2165 is `inline`, which means that the fio job threads submit and reap I/O
2166 directly. If set to `offload`, the job threads will offload I/O submission
2167 to a dedicated pool of I/O threads. This requires some coordination and thus
2168 has a bit of extra overhead, especially for lower queue depth I/O where it
2169 can increase latencies. The benefit is that fio can manage submission rates
2170 independently of the device completion rates. This avoids skewed latency
730bd7d9 2171 reporting if I/O gets backed up on the device side (the coordinated omission
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2172 problem).
2173
2174
2175I/O rate
2176~~~~~~~~
2177
a881438b 2178.. option:: thinktime=time
f80dba8d 2179
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2180 Stall the job for the specified period of time after an I/O has completed before issuing the
2181 next. May be used to simulate processing being done by an application.
947e0fe0 2182 When the unit is omitted, the value is interpreted in microseconds. See
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2183 :option:`thinktime_blocks` and :option:`thinktime_spin`.
2184
a881438b 2185.. option:: thinktime_spin=time
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2186
2187 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
2188 something with the data received, before falling back to sleeping for the
f75ede1d 2189 rest of the period specified by :option:`thinktime`. When the unit is
947e0fe0 2190 omitted, the value is interpreted in microseconds.
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2191
2192.. option:: thinktime_blocks=int
2193
2194 Only valid if :option:`thinktime` is set - control how many blocks to issue,
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2195 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
2196 fio wait :option:`thinktime` usecs after every block. This effectively makes any
f80dba8d 2197 queue depth setting redundant, since no more than 1 I/O will be queued
f50fbdda 2198 before we have to complete it and do our :option:`thinktime`. In other words, this
f80dba8d 2199 setting effectively caps the queue depth if the latter is larger.
71bfa161 2200
f80dba8d 2201.. option:: rate=int[,int][,int]
71bfa161 2202
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2203 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
2204 suffix rules apply. Comma-separated values may be specified for reads,
2205 writes, and trims as described in :option:`blocksize`.
71bfa161 2206
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2207 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
2208 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
2209 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
2210 latter will only limit reads.
2211
f80dba8d 2212.. option:: rate_min=int[,int][,int]
71bfa161 2213
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2214 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
2215 to meet this requirement will cause the job to exit. Comma-separated values
2216 may be specified for reads, writes, and trims as described in
2217 :option:`blocksize`.
71bfa161 2218
f80dba8d 2219.. option:: rate_iops=int[,int][,int]
71bfa161 2220
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2221 Cap the bandwidth to this number of IOPS. Basically the same as
2222 :option:`rate`, just specified independently of bandwidth. If the job is
2223 given a block size range instead of a fixed value, the smallest block size
2224 is used as the metric. Comma-separated values may be specified for reads,
2225 writes, and trims as described in :option:`blocksize`.
71bfa161 2226
f80dba8d 2227.. option:: rate_iops_min=int[,int][,int]
71bfa161 2228
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2229 If fio doesn't meet this rate of I/O, it will cause the job to exit.
2230 Comma-separated values may be specified for reads, writes, and trims as
2231 described in :option:`blocksize`.
71bfa161 2232
f80dba8d 2233.. option:: rate_process=str
66c098b8 2234
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2235 This option controls how fio manages rated I/O submissions. The default is
2236 `linear`, which submits I/O in a linear fashion with fixed delays between
c60ebc45 2237 I/Os that gets adjusted based on I/O completion rates. If this is set to
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2238 `poisson`, fio will submit I/O based on a more real world random request
2239 flow, known as the Poisson process
2240 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
2241 10^6 / IOPS for the given workload.
71bfa161 2242
1a9bf814
JA
2243.. option:: rate_ignore_thinktime=bool
2244
2245 By default, fio will attempt to catch up to the specified rate setting,
2246 if any kind of thinktime setting was used. If this option is set, then
2247 fio will ignore the thinktime and continue doing IO at the specified
2248 rate, instead of entering a catch-up mode after thinktime is done.
2249
71bfa161 2250
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2251I/O latency
2252~~~~~~~~~~~
71bfa161 2253
a881438b 2254.. option:: latency_target=time
71bfa161 2255
f80dba8d 2256 If set, fio will attempt to find the max performance point that the given
f75ede1d 2257 workload will run at while maintaining a latency below this target. When
947e0fe0 2258 the unit is omitted, the value is interpreted in microseconds. See
f75ede1d 2259 :option:`latency_window` and :option:`latency_percentile`.
71bfa161 2260
a881438b 2261.. option:: latency_window=time
71bfa161 2262
f80dba8d 2263 Used with :option:`latency_target` to specify the sample window that the job
f75ede1d 2264 is run at varying queue depths to test the performance. When the unit is
947e0fe0 2265 omitted, the value is interpreted in microseconds.
b4692828 2266
f80dba8d 2267.. option:: latency_percentile=float
71bfa161 2268
c60ebc45 2269 The percentage of I/Os that must fall within the criteria specified by
f80dba8d 2270 :option:`latency_target` and :option:`latency_window`. If not set, this
c60ebc45 2271 defaults to 100.0, meaning that all I/Os must be equal or below to the value
f80dba8d 2272 set by :option:`latency_target`.
71bfa161 2273
a881438b 2274.. option:: max_latency=time
71bfa161 2275
f75ede1d 2276 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
947e0fe0 2277 maximum latency. When the unit is omitted, the value is interpreted in
f75ede1d 2278 microseconds.
71bfa161 2279
f80dba8d 2280.. option:: rate_cycle=int
71bfa161 2281
f80dba8d 2282 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
a47b697c 2283 of milliseconds. Defaults to 1000.
71bfa161 2284
71bfa161 2285
f80dba8d
MT
2286I/O replay
2287~~~~~~~~~~
71bfa161 2288
f80dba8d 2289.. option:: write_iolog=str
c2b1e753 2290
f80dba8d
MT
2291 Write the issued I/O patterns to the specified file. See
2292 :option:`read_iolog`. Specify a separate file for each job, otherwise the
2293 iologs will be interspersed and the file may be corrupt.
c2b1e753 2294
f80dba8d 2295.. option:: read_iolog=str
71bfa161 2296
22413915 2297 Open an iolog with the specified filename and replay the I/O patterns it
f80dba8d
MT
2298 contains. This can be used to store a workload and replay it sometime
2299 later. The iolog given may also be a blktrace binary file, which allows fio
2300 to replay a workload captured by :command:`blktrace`. See
2301 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
2302 replay, the file needs to be turned into a blkparse binary data file first
2303 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
71bfa161 2304
589e88b7 2305.. option:: replay_no_stall=bool
71bfa161 2306
f80dba8d 2307 When replaying I/O with :option:`read_iolog` the default behavior is to
22413915 2308 attempt to respect the timestamps within the log and replay them with the
f80dba8d
MT
2309 appropriate delay between IOPS. By setting this variable fio will not
2310 respect the timestamps and attempt to replay them as fast as possible while
2311 still respecting ordering. The result is the same I/O pattern to a given
2312 device, but different timings.
71bfa161 2313
6dd7fa77
JA
2314.. option:: replay_time_scale=int
2315
2316 When replaying I/O with :option:`read_iolog`, fio will honor the
2317 original timing in the trace. With this option, it's possible to scale
2318 the time. It's a percentage option, if set to 50 it means run at 50%
2319 the original IO rate in the trace. If set to 200, run at twice the
2320 original IO rate. Defaults to 100.
2321
f80dba8d 2322.. option:: replay_redirect=str
b4692828 2323
f80dba8d
MT
2324 While replaying I/O patterns using :option:`read_iolog` the default behavior
2325 is to replay the IOPS onto the major/minor device that each IOP was recorded
2326 from. This is sometimes undesirable because on a different machine those
2327 major/minor numbers can map to a different device. Changing hardware on the
2328 same system can also result in a different major/minor mapping.
730bd7d9 2329 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
f80dba8d 2330 device regardless of the device it was recorded
9207a0cb 2331 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
f80dba8d
MT
2332 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
2333 multiple devices will be replayed onto a single device, if the trace
2334 contains multiple devices. If you want multiple devices to be replayed
2335 concurrently to multiple redirected devices you must blkparse your trace
2336 into separate traces and replay them with independent fio invocations.
2337 Unfortunately this also breaks the strict time ordering between multiple
2338 device accesses.
71bfa161 2339
f80dba8d 2340.. option:: replay_align=int
74929ac2 2341
f80dba8d
MT
2342 Force alignment of I/O offsets and lengths in a trace to this power of 2
2343 value.
3c54bc46 2344
f80dba8d 2345.. option:: replay_scale=int
3c54bc46 2346
f80dba8d 2347 Scale sector offsets down by this factor when replaying traces.
3c54bc46 2348
3c54bc46 2349
f80dba8d
MT
2350Threads, processes and job synchronization
2351~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3c54bc46 2352
f80dba8d 2353.. option:: thread
3c54bc46 2354
730bd7d9
SW
2355 Fio defaults to creating jobs by using fork, however if this option is
2356 given, fio will create jobs by using POSIX Threads' function
2357 :manpage:`pthread_create(3)` to create threads instead.
71bfa161 2358
f80dba8d 2359.. option:: wait_for=str
74929ac2 2360
730bd7d9
SW
2361 If set, the current job won't be started until all workers of the specified
2362 waitee job are done.
74929ac2 2363
f80dba8d
MT
2364 ``wait_for`` operates on the job name basis, so there are a few
2365 limitations. First, the waitee must be defined prior to the waiter job
2366 (meaning no forward references). Second, if a job is being referenced as a
2367 waitee, it must have a unique name (no duplicate waitees).
74929ac2 2368
f80dba8d 2369.. option:: nice=int
892a6ffc 2370
f80dba8d 2371 Run the job with the given nice value. See man :manpage:`nice(2)`.
892a6ffc 2372
f80dba8d
MT
2373 On Windows, values less than -15 set the process class to "High"; -1 through
2374 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
2375 priority class.
74929ac2 2376
f80dba8d 2377.. option:: prio=int
71bfa161 2378
f80dba8d
MT
2379 Set the I/O priority value of this job. Linux limits us to a positive value
2380 between 0 and 7, with 0 being the highest. See man
2381 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
2382 systems since meaning of priority may differ.
71bfa161 2383
f80dba8d 2384.. option:: prioclass=int
d59aa780 2385
f80dba8d 2386 Set the I/O priority class. See man :manpage:`ionice(1)`.
d59aa780 2387
f80dba8d 2388.. option:: cpus_allowed=str
6d500c2e 2389
730bd7d9 2390 Controls the same options as :option:`cpumask`, but accepts a textual
b570e037
SW
2391 specification of the permitted CPUs instead and CPUs are indexed from 0. So
2392 to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
2393 allows a range of CPUs to be specified -- say you wanted a binding to CPUs
2394 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
2395
2396 On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
2397 processor group will be used and affinity settings are inherited from the
2398 system. An fio build configured to target Windows 7 makes options that set
2399 CPUs processor group aware and values will set both the processor group
2400 and a CPU from within that group. For example, on a system where processor
2401 group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
2402 values between 0 and 39 will bind CPUs from processor group 0 and
2403 ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
2404 group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
2405 single ``cpus_allowed`` option must be from the same processor group. For
2406 Windows fio builds not built for Windows 7, CPUs will only be selected from
2407 (and be relative to) whatever processor group fio happens to be running in
2408 and CPUs from other processor groups cannot be used.
6d500c2e 2409
f80dba8d 2410.. option:: cpus_allowed_policy=str
6d500c2e 2411
f80dba8d 2412 Set the policy of how fio distributes the CPUs specified by
730bd7d9 2413 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
6d500c2e 2414
f80dba8d
MT
2415 **shared**
2416 All jobs will share the CPU set specified.
2417 **split**
2418 Each job will get a unique CPU from the CPU set.
6d500c2e 2419
22413915 2420 **shared** is the default behavior, if the option isn't specified. If
f80dba8d
MT
2421 **split** is specified, then fio will will assign one cpu per job. If not
2422 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
2423 in the set.
6d500c2e 2424
b570e037
SW
2425.. option:: cpumask=int
2426
2427 Set the CPU affinity of this job. The parameter given is a bit mask of
2428 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
2429 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
2430 :manpage:`sched_setaffinity(2)`. This may not work on all supported
2431 operating systems or kernel versions. This option doesn't work well for a
2432 higher CPU count than what you can store in an integer mask, so it can only
2433 control cpus 1-32. For boxes with larger CPU counts, use
2434 :option:`cpus_allowed`.
2435
f80dba8d 2436.. option:: numa_cpu_nodes=str
6d500c2e 2437
f80dba8d
MT
2438 Set this job running on specified NUMA nodes' CPUs. The arguments allow
2439 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
ac8ca2af 2440 NUMA options support, fio must be built on a system with libnuma-dev(el)
f80dba8d 2441 installed.
61b9861d 2442
f80dba8d 2443.. option:: numa_mem_policy=str
61b9861d 2444
f80dba8d
MT
2445 Set this job's memory policy and corresponding NUMA nodes. Format of the
2446 arguments::
5c94b008 2447
f80dba8d 2448 <mode>[:<nodelist>]
ce35b1ec 2449
804c0839 2450 ``mode`` is one of the following memory policies: ``default``, ``prefer``,
730bd7d9
SW
2451 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
2452 policies, no node needs to be specified. For ``prefer``, only one node is
2453 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
2454 follows: a comma delimited list of numbers, A-B ranges, or `all`.
71bfa161 2455
f80dba8d 2456.. option:: cgroup=str
390b1537 2457
f80dba8d
MT
2458 Add job to this control group. If it doesn't exist, it will be created. The
2459 system must have a mounted cgroup blkio mount point for this to work. If
2460 your system doesn't have it mounted, you can do so with::
5af1c6f3 2461
f80dba8d 2462 # mount -t cgroup -o blkio none /cgroup
5af1c6f3 2463
f80dba8d 2464.. option:: cgroup_weight=int
5af1c6f3 2465
f80dba8d
MT
2466 Set the weight of the cgroup to this value. See the documentation that comes
2467 with the kernel, allowed values are in the range of 100..1000.
a086c257 2468
f80dba8d 2469.. option:: cgroup_nodelete=bool
8c07860d 2470
f80dba8d
MT
2471 Normally fio will delete the cgroups it has created after the job
2472 completion. To override this behavior and to leave cgroups around after the
2473 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
2474 to inspect various cgroup files after job completion. Default: false.
8c07860d 2475
f80dba8d 2476.. option:: flow_id=int
8c07860d 2477
f80dba8d
MT
2478 The ID of the flow. If not specified, it defaults to being a global
2479 flow. See :option:`flow`.
1907dbc6 2480
f80dba8d 2481.. option:: flow=int
71bfa161 2482
f80dba8d
MT
2483 Weight in token-based flow control. If this value is used, then there is a
2484 'flow counter' which is used to regulate the proportion of activity between
2485 two or more jobs. Fio attempts to keep this flow counter near zero. The
2486 ``flow`` parameter stands for how much should be added or subtracted to the
2487 flow counter on each iteration of the main I/O loop. That is, if one job has
2488 ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
2489 ratio in how much one runs vs the other.
71bfa161 2490
f80dba8d 2491.. option:: flow_watermark=int
a31041ea 2492
f80dba8d
MT
2493 The maximum value that the absolute value of the flow counter is allowed to
2494 reach before the job must wait for a lower value of the counter.
82407585 2495
f80dba8d 2496.. option:: flow_sleep=int
82407585 2497
f80dba8d
MT
2498 The period of time, in microseconds, to wait after the flow watermark has
2499 been exceeded before retrying operations.
82407585 2500
f80dba8d 2501.. option:: stonewall, wait_for_previous
82407585 2502
f80dba8d
MT
2503 Wait for preceding jobs in the job file to exit, before starting this
2504 one. Can be used to insert serialization points in the job file. A stone
2505 wall also implies starting a new reporting group, see
2506 :option:`group_reporting`.
2507
2508.. option:: exitall
2509
730bd7d9
SW
2510 By default, fio will continue running all other jobs when one job finishes
2511 but sometimes this is not the desired action. Setting ``exitall`` will
2512 instead make fio terminate all other jobs when one job finishes.
f80dba8d
MT
2513
2514.. option:: exec_prerun=str
2515
2516 Before running this job, issue the command specified through
2517 :manpage:`system(3)`. Output is redirected in a file called
2518 :file:`jobname.prerun.txt`.
2519
2520.. option:: exec_postrun=str
2521
2522 After the job completes, issue the command specified though
2523 :manpage:`system(3)`. Output is redirected in a file called
2524 :file:`jobname.postrun.txt`.
2525
2526.. option:: uid=int
2527
2528 Instead of running as the invoking user, set the user ID to this value
2529 before the thread/process does any work.
2530
2531.. option:: gid=int
2532
2533 Set group ID, see :option:`uid`.
2534
2535
2536Verification
2537~~~~~~~~~~~~
2538
2539.. option:: verify_only
2540
2541 Do not perform specified workload, only verify data still matches previous
2542 invocation of this workload. This option allows one to check data multiple
2543 times at a later date without overwriting it. This option makes sense only
2544 for workloads that write data, and does not support workloads with the
2545 :option:`time_based` option set.
2546
2547.. option:: do_verify=bool
2548
2549 Run the verify phase after a write phase. Only valid if :option:`verify` is
2550 set. Default: true.
2551
2552.. option:: verify=str
2553
2554 If writing to a file, fio can verify the file contents after each iteration
2555 of the job. Each verification method also implies verification of special
2556 header, which is written to the beginning of each block. This header also
2557 includes meta information, like offset of the block, block number, timestamp
2558 when block was written, etc. :option:`verify` can be combined with
2559 :option:`verify_pattern` option. The allowed values are:
2560
2561 **md5**
2562 Use an md5 sum of the data area and store it in the header of
2563 each block.
2564
2565 **crc64**
2566 Use an experimental crc64 sum of the data area and store it in the
2567 header of each block.
2568
2569 **crc32c**
a5896300
SW
2570 Use a crc32c sum of the data area and store it in the header of
2571 each block. This will automatically use hardware acceleration
2572 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
2573 fall back to software crc32c if none is found. Generally the
804c0839 2574 fastest checksum fio supports when hardware accelerated.
f80dba8d
MT
2575
2576 **crc32c-intel**
a5896300 2577 Synonym for crc32c.
f80dba8d
MT
2578
2579 **crc32**
2580 Use a crc32 sum of the data area and store it in the header of each
2581 block.
2582
2583 **crc16**
2584 Use a crc16 sum of the data area and store it in the header of each
2585 block.
2586
2587 **crc7**
2588 Use a crc7 sum of the data area and store it in the header of each
2589 block.
2590
2591 **xxhash**
2592 Use xxhash as the checksum function. Generally the fastest software
2593 checksum that fio supports.
2594
2595 **sha512**
2596 Use sha512 as the checksum function.
2597
2598 **sha256**
2599 Use sha256 as the checksum function.
2600
2601 **sha1**
2602 Use optimized sha1 as the checksum function.
82407585 2603
ae3a5acc
JA
2604 **sha3-224**
2605 Use optimized sha3-224 as the checksum function.
2606
2607 **sha3-256**
2608 Use optimized sha3-256 as the checksum function.
2609
2610 **sha3-384**
2611 Use optimized sha3-384 as the checksum function.
2612
2613 **sha3-512**
2614 Use optimized sha3-512 as the checksum function.
2615
f80dba8d
MT
2616 **meta**
2617 This option is deprecated, since now meta information is included in
2618 generic verification header and meta verification happens by
2619 default. For detailed information see the description of the
2620 :option:`verify` setting. This option is kept because of
2621 compatibility's sake with old configurations. Do not use it.
2622
2623 **pattern**
2624 Verify a strict pattern. Normally fio includes a header with some
2625 basic information and checksumming, but if this option is set, only
2626 the specific pattern set with :option:`verify_pattern` is verified.
2627
2628 **null**
2629 Only pretend to verify. Useful for testing internals with
9207a0cb 2630 :option:`ioengine`\=null, not for much else.
f80dba8d
MT
2631
2632 This option can be used for repeated burn-in tests of a system to make sure
2633 that the written data is also correctly read back. If the data direction
2634 given is a read or random read, fio will assume that it should verify a
2635 previously written file. If the data direction includes any form of write,
2636 the verify will be of the newly written data.
2637
f80dba8d
MT
2638.. option:: verify_offset=int
2639
2640 Swap the verification header with data somewhere else in the block before
2641 writing. It is swapped back before verifying.
2642
2643.. option:: verify_interval=int
2644
2645 Write the verification header at a finer granularity than the
2646 :option:`blocksize`. It will be written for chunks the size of
2647 ``verify_interval``. :option:`blocksize` should divide this evenly.
2648
2649.. option:: verify_pattern=str
2650
2651 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
2652 filling with totally random bytes, but sometimes it's interesting to fill
2653 with a known pattern for I/O verification purposes. Depending on the width
730bd7d9 2654 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
f80dba8d
MT
2655 be either a decimal or a hex number). The ``verify_pattern`` if larger than
2656 a 32-bit quantity has to be a hex number that starts with either "0x" or
2657 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
2658 format, which means that for each block offset will be written and then
2659 verified back, e.g.::
61b9861d
RP
2660
2661 verify_pattern=%o
2662
f80dba8d
MT
2663 Or use combination of everything::
2664
61b9861d 2665 verify_pattern=0xff%o"abcd"-12
e28218f3 2666
f80dba8d
MT
2667.. option:: verify_fatal=bool
2668
2669 Normally fio will keep checking the entire contents before quitting on a
2670 block verification failure. If this option is set, fio will exit the job on
2671 the first observed failure. Default: false.
2672
2673.. option:: verify_dump=bool
2674
2675 If set, dump the contents of both the original data block and the data block
2676 we read off disk to files. This allows later analysis to inspect just what
2677 kind of data corruption occurred. Off by default.
2678
2679.. option:: verify_async=int
2680
2681 Fio will normally verify I/O inline from the submitting thread. This option
2682 takes an integer describing how many async offload threads to create for I/O
2683 verification instead, causing fio to offload the duty of verifying I/O
2684 contents to one or more separate threads. If using this offload option, even
2685 sync I/O engines can benefit from using an :option:`iodepth` setting higher
2686 than 1, as it allows them to have I/O in flight while verifies are running.
d7e6ea1c 2687 Defaults to 0 async threads, i.e. verification is not asynchronous.
f80dba8d
MT
2688
2689.. option:: verify_async_cpus=str
2690
2691 Tell fio to set the given CPU affinity on the async I/O verification
2692 threads. See :option:`cpus_allowed` for the format used.
2693
2694.. option:: verify_backlog=int
2695
2696 Fio will normally verify the written contents of a job that utilizes verify
2697 once that job has completed. In other words, everything is written then
2698 everything is read back and verified. You may want to verify continually
2699 instead for a variety of reasons. Fio stores the meta data associated with
2700 an I/O block in memory, so for large verify workloads, quite a bit of memory
2701 would be used up holding this meta data. If this option is enabled, fio will
2702 write only N blocks before verifying these blocks.
2703
2704.. option:: verify_backlog_batch=int
2705
2706 Control how many blocks fio will verify if :option:`verify_backlog` is
2707 set. If not set, will default to the value of :option:`verify_backlog`
2708 (meaning the entire queue is read back and verified). If
2709 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
2710 blocks will be verified, if ``verify_backlog_batch`` is larger than
2711 :option:`verify_backlog`, some blocks will be verified more than once.
2712
2713.. option:: verify_state_save=bool
2714
2715 When a job exits during the write phase of a verify workload, save its
2716 current state. This allows fio to replay up until that point, if the verify
2717 state is loaded for the verify read phase. The format of the filename is,
2718 roughly::
2719
f50fbdda 2720 <type>-<jobname>-<jobindex>-verify.state.
f80dba8d
MT
2721
2722 <type> is "local" for a local run, "sock" for a client/server socket
2723 connection, and "ip" (192.168.0.1, for instance) for a networked
d7e6ea1c 2724 client/server connection. Defaults to true.
f80dba8d
MT
2725
2726.. option:: verify_state_load=bool
2727
2728 If a verify termination trigger was used, fio stores the current write state
2729 of each thread. This can be used at verification time so that fio knows how
2730 far it should verify. Without this information, fio will run a full
a47b697c
SW
2731 verification pass, according to the settings in the job file used. Default
2732 false.
f80dba8d
MT
2733
2734.. option:: trim_percentage=int
2735
2736 Number of verify blocks to discard/trim.
2737
2738.. option:: trim_verify_zero=bool
2739
22413915 2740 Verify that trim/discarded blocks are returned as zeros.
f80dba8d
MT
2741
2742.. option:: trim_backlog=int
2743
5cfd1e9a 2744 Trim after this number of blocks are written.
f80dba8d
MT
2745
2746.. option:: trim_backlog_batch=int
2747
2748 Trim this number of I/O blocks.
2749
2750.. option:: experimental_verify=bool
2751
2752 Enable experimental verification.
2753
f80dba8d
MT
2754Steady state
2755~~~~~~~~~~~~
2756
2757.. option:: steadystate=str:float, ss=str:float
2758
2759 Define the criterion and limit for assessing steady state performance. The
2760 first parameter designates the criterion whereas the second parameter sets
2761 the threshold. When the criterion falls below the threshold for the
2762 specified duration, the job will stop. For example, `iops_slope:0.1%` will
2763 direct fio to terminate the job when the least squares regression slope
2764 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
2765 this will apply to all jobs in the group. Below is the list of available
2766 steady state assessment criteria. All assessments are carried out using only
2767 data from the rolling collection window. Threshold limits can be expressed
2768 as a fixed value or as a percentage of the mean in the collection window.
2769
2770 **iops**
2771 Collect IOPS data. Stop the job if all individual IOPS measurements
2772 are within the specified limit of the mean IOPS (e.g., ``iops:2``
2773 means that all individual IOPS values must be within 2 of the mean,
2774 whereas ``iops:0.2%`` means that all individual IOPS values must be
2775 within 0.2% of the mean IOPS to terminate the job).
2776
2777 **iops_slope**
2778 Collect IOPS data and calculate the least squares regression
2779 slope. Stop the job if the slope falls below the specified limit.
2780
2781 **bw**
2782 Collect bandwidth data. Stop the job if all individual bandwidth
2783 measurements are within the specified limit of the mean bandwidth.
2784
2785 **bw_slope**
2786 Collect bandwidth data and calculate the least squares regression
2787 slope. Stop the job if the slope falls below the specified limit.
2788
2789.. option:: steadystate_duration=time, ss_dur=time
2790
2791 A rolling window of this duration will be used to judge whether steady state
2792 has been reached. Data will be collected once per second. The default is 0
f75ede1d 2793 which disables steady state detection. When the unit is omitted, the
947e0fe0 2794 value is interpreted in seconds.
f80dba8d
MT
2795
2796.. option:: steadystate_ramp_time=time, ss_ramp=time
2797
2798 Allow the job to run for the specified duration before beginning data
2799 collection for checking the steady state job termination criterion. The
947e0fe0 2800 default is 0. When the unit is omitted, the value is interpreted in seconds.
f80dba8d
MT
2801
2802
2803Measurements and reporting
2804~~~~~~~~~~~~~~~~~~~~~~~~~~
2805
2806.. option:: per_job_logs=bool
2807
2808 If set, this generates bw/clat/iops log with per file private filenames. If
2809 not set, jobs with identical names will share the log filename. Default:
2810 true.
2811
2812.. option:: group_reporting
2813
2814 It may sometimes be interesting to display statistics for groups of jobs as
2815 a whole instead of for each individual job. This is especially true if
2816 :option:`numjobs` is used; looking at individual thread/process output
2817 quickly becomes unwieldy. To see the final report per-group instead of
2818 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
2819 same reporting group, unless if separated by a :option:`stonewall`, or by
2820 using :option:`new_group`.
2821
2822.. option:: new_group
2823
2824 Start a new reporting group. See: :option:`group_reporting`. If not given,
2825 all jobs in a file will be part of the same reporting group, unless
2826 separated by a :option:`stonewall`.
2827
589e88b7 2828.. option:: stats=bool
8243be59
JA
2829
2830 By default, fio collects and shows final output results for all jobs
2831 that run. If this option is set to 0, then fio will ignore it in
2832 the final stat output.
2833
f80dba8d
MT
2834.. option:: write_bw_log=str
2835
2836 If given, write a bandwidth log for this job. Can be used to store data of
074f0817 2837 the bandwidth of the jobs in their lifetime.
f80dba8d 2838
074f0817
SW
2839 If no str argument is given, the default filename of
2840 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
2841 will still append the type of log. So if one specifies::
2842
2843 write_bw_log=foo
f80dba8d 2844
074f0817
SW
2845 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
2846 of the job (`1..N`, where `N` is the number of jobs). If
2847 :option:`per_job_logs` is false, then the filename will not include the
2848 `.x` job index.
e3cedca7 2849
074f0817
SW
2850 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
2851 text files into nice graphs. See `Log File Formats`_ for how data is
2852 structured within the file.
2853
2854.. option:: write_lat_log=str
e3cedca7 2855
074f0817 2856 Same as :option:`write_bw_log`, except this option creates I/O
77b7e675
SW
2857 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
2858 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
074f0817
SW
2859 latency files instead. See :option:`write_bw_log` for details about
2860 the filename format and `Log File Formats`_ for how data is structured
2861 within the files.
be4ecfdf 2862
f80dba8d 2863.. option:: write_hist_log=str
06842027 2864
074f0817 2865 Same as :option:`write_bw_log` but writes an I/O completion latency
77b7e675 2866 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
074f0817
SW
2867 file will be empty unless :option:`log_hist_msec` has also been set.
2868 See :option:`write_bw_log` for details about the filename format and
2869 `Log File Formats`_ for how data is structured within the file.
06842027 2870
f80dba8d 2871.. option:: write_iops_log=str
06842027 2872
074f0817 2873 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
77b7e675 2874 :file:`name_iops.x.log`) instead. See :option:`write_bw_log` for
074f0817
SW
2875 details about the filename format and `Log File Formats`_ for how data
2876 is structured within the file.
06842027 2877
f80dba8d 2878.. option:: log_avg_msec=int
06842027 2879
f80dba8d
MT
2880 By default, fio will log an entry in the iops, latency, or bw log for every
2881 I/O that completes. When writing to the disk log, that can quickly grow to a
2882 very large size. Setting this option makes fio average the each log entry
2883 over the specified period of time, reducing the resolution of the log. See
2884 :option:`log_max_value` as well. Defaults to 0, logging all entries.
6fc82095 2885 Also see `Log File Formats`_.
06842027 2886
f80dba8d 2887.. option:: log_hist_msec=int
06842027 2888
f80dba8d
MT
2889 Same as :option:`log_avg_msec`, but logs entries for completion latency
2890 histograms. Computing latency percentiles from averages of intervals using
c60ebc45 2891 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
f80dba8d
MT
2892 histogram entries over the specified period of time, reducing log sizes for
2893 high IOPS devices while retaining percentile accuracy. See
074f0817
SW
2894 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
2895 Defaults to 0, meaning histogram logging is disabled.
06842027 2896
f80dba8d 2897.. option:: log_hist_coarseness=int
06842027 2898
f80dba8d
MT
2899 Integer ranging from 0 to 6, defining the coarseness of the resolution of
2900 the histogram logs enabled with :option:`log_hist_msec`. For each increment
2901 in coarseness, fio outputs half as many bins. Defaults to 0, for which
074f0817
SW
2902 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
2903 and `Log File Formats`_.
8b28bd41 2904
f80dba8d 2905.. option:: log_max_value=bool
66c098b8 2906
f80dba8d
MT
2907 If :option:`log_avg_msec` is set, fio logs the average over that window. If
2908 you instead want to log the maximum value, set this option to 1. Defaults to
2909 0, meaning that averaged values are logged.
a696fa2a 2910
589e88b7 2911.. option:: log_offset=bool
a696fa2a 2912
f80dba8d 2913 If this is set, the iolog options will include the byte offset for the I/O
5a83478f
SW
2914 entry as well as the other data values. Defaults to 0 meaning that
2915 offsets are not present in logs. Also see `Log File Formats`_.
71bfa161 2916
f80dba8d 2917.. option:: log_compression=int
7de87099 2918
f80dba8d
MT
2919 If this is set, fio will compress the I/O logs as it goes, to keep the
2920 memory footprint lower. When a log reaches the specified size, that chunk is
2921 removed and compressed in the background. Given that I/O logs are fairly
2922 highly compressible, this yields a nice memory savings for longer runs. The
2923 downside is that the compression will consume some background CPU cycles, so
2924 it may impact the run. This, however, is also true if the logging ends up
2925 consuming most of the system memory. So pick your poison. The I/O logs are
2926 saved normally at the end of a run, by decompressing the chunks and storing
2927 them in the specified log file. This feature depends on the availability of
2928 zlib.
e0b0d892 2929
f80dba8d 2930.. option:: log_compression_cpus=str
e0b0d892 2931
f80dba8d
MT
2932 Define the set of CPUs that are allowed to handle online log compression for
2933 the I/O jobs. This can provide better isolation between performance
0cf90a62
SW
2934 sensitive jobs, and background compression work. See
2935 :option:`cpus_allowed` for the format used.
9e684a49 2936
f80dba8d 2937.. option:: log_store_compressed=bool
9e684a49 2938
f80dba8d
MT
2939 If set, fio will store the log files in a compressed format. They can be
2940 decompressed with fio, using the :option:`--inflate-log` command line
2941 parameter. The files will be stored with a :file:`.fz` suffix.
9e684a49 2942
f80dba8d 2943.. option:: log_unix_epoch=bool
9e684a49 2944
f80dba8d
MT
2945 If set, fio will log Unix timestamps to the log files produced by enabling
2946 write_type_log for each log type, instead of the default zero-based
2947 timestamps.
2948
2949.. option:: block_error_percentiles=bool
2950
2951 If set, record errors in trim block-sized units from writes and trims and
2952 output a histogram of how many trims it took to get to errors, and what kind
2953 of error was encountered.
2954
2955.. option:: bwavgtime=int
2956
2957 Average the calculated bandwidth over the given time. Value is specified in
2958 milliseconds. If the job also does bandwidth logging through
2959 :option:`write_bw_log`, then the minimum of this option and
2960 :option:`log_avg_msec` will be used. Default: 500ms.
2961
2962.. option:: iopsavgtime=int
2963
2964 Average the calculated IOPS over the given time. Value is specified in
2965 milliseconds. If the job also does IOPS logging through
2966 :option:`write_iops_log`, then the minimum of this option and
2967 :option:`log_avg_msec` will be used. Default: 500ms.
2968
2969.. option:: disk_util=bool
2970
2971 Generate disk utilization statistics, if the platform supports it.
2972 Default: true.
2973
2974.. option:: disable_lat=bool
2975
2976 Disable measurements of total latency numbers. Useful only for cutting back
2977 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
2978 performance at really high IOPS rates. Note that to really get rid of a
2979 large amount of these calls, this option must be used with
f75ede1d 2980 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
f80dba8d
MT
2981
2982.. option:: disable_clat=bool
2983
2984 Disable measurements of completion latency numbers. See
2985 :option:`disable_lat`.
2986
2987.. option:: disable_slat=bool
2988
2989 Disable measurements of submission latency numbers. See
f50fbdda 2990 :option:`disable_lat`.
f80dba8d 2991
f75ede1d 2992.. option:: disable_bw_measurement=bool, disable_bw=bool
f80dba8d
MT
2993
2994 Disable measurements of throughput/bandwidth numbers. See
2995 :option:`disable_lat`.
2996
2997.. option:: clat_percentiles=bool
2998
b599759b
JA
2999 Enable the reporting of percentiles of completion latencies. This
3000 option is mutually exclusive with :option:`lat_percentiles`.
3001
3002.. option:: lat_percentiles=bool
3003
b71968b1 3004 Enable the reporting of percentiles of I/O latencies. This is similar
b599759b
JA
3005 to :option:`clat_percentiles`, except that this includes the
3006 submission latency. This option is mutually exclusive with
3007 :option:`clat_percentiles`.
f80dba8d
MT
3008
3009.. option:: percentile_list=float_list
3010
c32ba107
JA
3011 Overwrite the default list of percentiles for completion latencies and
3012 the block error histogram. Each number is a floating number in the
3013 range (0,100], and the maximum length of the list is 20. Use ``:`` to
3014 separate the numbers, and list the numbers in ascending order. For
3015 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
3016 values of completion latency below which 99.5% and 99.9% of the observed
3017 latencies fell, respectively.
f80dba8d 3018
e883cb35
JF
3019.. option:: significant_figures=int
3020
c32ba107
JA
3021 If using :option:`--output-format` of `normal`, set the significant
3022 figures to this value. Higher values will yield more precise IOPS and
3023 throughput units, while lower values will round. Requires a minimum
3024 value of 1 and a maximum value of 10. Defaults to 4.
e883cb35 3025
f80dba8d
MT
3026
3027Error handling
3028~~~~~~~~~~~~~~
3029
3030.. option:: exitall_on_error
3031
3032 When one job finishes in error, terminate the rest. The default is to wait
3033 for each job to finish.
3034
3035.. option:: continue_on_error=str
3036
3037 Normally fio will exit the job on the first observed failure. If this option
3038 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
3039 EILSEQ) until the runtime is exceeded or the I/O size specified is
3040 completed. If this option is used, there are two more stats that are
3041 appended, the total error count and the first error. The error field given
3042 in the stats is the first error that was hit during the run.
3043
3044 The allowed values are:
3045
3046 **none**
3047 Exit on any I/O or verify errors.
3048
3049 **read**
3050 Continue on read errors, exit on all others.
3051
3052 **write**
3053 Continue on write errors, exit on all others.
3054
3055 **io**
3056 Continue on any I/O error, exit on all others.
3057
3058 **verify**
3059 Continue on verify errors, exit on all others.
3060
3061 **all**
3062 Continue on all errors.
3063
3064 **0**
3065 Backward-compatible alias for 'none'.
3066
3067 **1**
3068 Backward-compatible alias for 'all'.
3069
3070.. option:: ignore_error=str
3071
3072 Sometimes you want to ignore some errors during test in that case you can
a35ef7cb
TK
3073 specify error list for each error type, instead of only being able to
3074 ignore the default 'non-fatal error' using :option:`continue_on_error`.
f80dba8d
MT
3075 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
3076 given error type is separated with ':'. Error may be symbol ('ENOSPC',
3077 'ENOMEM') or integer. Example::
3078
3079 ignore_error=EAGAIN,ENOSPC:122
3080
3081 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
a35ef7cb
TK
3082 WRITE. This option works by overriding :option:`continue_on_error` with
3083 the list of errors for each error type if any.
f80dba8d
MT
3084
3085.. option:: error_dump=bool
3086
3087 If set dump every error even if it is non fatal, true by default. If
3088 disabled only fatal error will be dumped.
3089
f75ede1d
SW
3090Running predefined workloads
3091----------------------------
3092
3093Fio includes predefined profiles that mimic the I/O workloads generated by
3094other tools.
3095
3096.. option:: profile=str
3097
3098 The predefined workload to run. Current profiles are:
3099
3100 **tiobench**
3101 Threaded I/O bench (tiotest/tiobench) like workload.
3102
3103 **act**
3104 Aerospike Certification Tool (ACT) like workload.
3105
3106To view a profile's additional options use :option:`--cmdhelp` after specifying
3107the profile. For example::
3108
f50fbdda 3109 $ fio --profile=act --cmdhelp
f75ede1d
SW
3110
3111Act profile options
3112~~~~~~~~~~~~~~~~~~~
3113
3114.. option:: device-names=str
3115 :noindex:
3116
3117 Devices to use.
3118
3119.. option:: load=int
3120 :noindex:
3121
3122 ACT load multiplier. Default: 1.
3123
3124.. option:: test-duration=time
3125 :noindex:
3126
947e0fe0
SW
3127 How long the entire test takes to run. When the unit is omitted, the value
3128 is given in seconds. Default: 24h.
f75ede1d
SW
3129
3130.. option:: threads-per-queue=int
3131 :noindex:
3132
f50fbdda 3133 Number of read I/O threads per device. Default: 8.
f75ede1d
SW
3134
3135.. option:: read-req-num-512-blocks=int
3136 :noindex:
3137
3138 Number of 512B blocks to read at the time. Default: 3.
3139
3140.. option:: large-block-op-kbytes=int
3141 :noindex:
3142
3143 Size of large block ops in KiB (writes). Default: 131072.
3144
3145.. option:: prep
3146 :noindex:
3147
3148 Set to run ACT prep phase.
3149
3150Tiobench profile options
3151~~~~~~~~~~~~~~~~~~~~~~~~
3152
3153.. option:: size=str
3154 :noindex:
3155
f50fbdda 3156 Size in MiB.
f75ede1d
SW
3157
3158.. option:: block=int
3159 :noindex:
3160
3161 Block size in bytes. Default: 4096.
3162
3163.. option:: numruns=int
3164 :noindex:
3165
3166 Number of runs.
3167
3168.. option:: dir=str
3169 :noindex:
3170
3171 Test directory.
3172
3173.. option:: threads=int
3174 :noindex:
3175
3176 Number of threads.
f80dba8d
MT
3177
3178Interpreting the output
3179-----------------------
3180
36214730
SW
3181..
3182 Example output was based on the following:
3183 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
3184 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
3185 --runtime=2m --rw=rw
3186
f80dba8d
MT
3187Fio spits out a lot of output. While running, fio will display the status of the
3188jobs created. An example of that would be::
3189
9d25d068 3190 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 3191
36214730
SW
3192The characters inside the first set of square brackets denote the current status of
3193each thread. The first character is the first job defined in the job file, and so
3194forth. The possible values (in typical life cycle order) are:
f80dba8d
MT
3195
3196+------+-----+-----------------------------------------------------------+
3197| Idle | Run | |
3198+======+=====+===========================================================+
3199| P | | Thread setup, but not started. |
3200+------+-----+-----------------------------------------------------------+
3201| C | | Thread created. |
3202+------+-----+-----------------------------------------------------------+
3203| I | | Thread initialized, waiting or generating necessary data. |
3204+------+-----+-----------------------------------------------------------+
3205| | p | Thread running pre-reading file(s). |
3206+------+-----+-----------------------------------------------------------+
36214730
SW
3207| | / | Thread is in ramp period. |
3208+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3209| | R | Running, doing sequential reads. |
3210+------+-----+-----------------------------------------------------------+
3211| | r | Running, doing random reads. |
3212+------+-----+-----------------------------------------------------------+
3213| | W | Running, doing sequential writes. |
3214+------+-----+-----------------------------------------------------------+
3215| | w | Running, doing random writes. |
3216+------+-----+-----------------------------------------------------------+
3217| | M | Running, doing mixed sequential reads/writes. |
3218+------+-----+-----------------------------------------------------------+
3219| | m | Running, doing mixed random reads/writes. |
3220+------+-----+-----------------------------------------------------------+
36214730
SW
3221| | D | Running, doing sequential trims. |
3222+------+-----+-----------------------------------------------------------+
3223| | d | Running, doing random trims. |
3224+------+-----+-----------------------------------------------------------+
3225| | F | Running, currently waiting for :manpage:`fsync(2)`. |
f80dba8d
MT
3226+------+-----+-----------------------------------------------------------+
3227| | V | Running, doing verification of written data. |
3228+------+-----+-----------------------------------------------------------+
36214730
SW
3229| f | | Thread finishing. |
3230+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3231| E | | Thread exited, not reaped by main thread yet. |
3232+------+-----+-----------------------------------------------------------+
36214730 3233| _ | | Thread reaped. |
f80dba8d
MT
3234+------+-----+-----------------------------------------------------------+
3235| X | | Thread reaped, exited with an error. |
3236+------+-----+-----------------------------------------------------------+
3237| K | | Thread reaped, exited due to signal. |
3238+------+-----+-----------------------------------------------------------+
3239
36214730
SW
3240..
3241 Example output was based on the following:
3242 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
3243 --time_based --rate=2512k --bs=256K --numjobs=10 \
3244 --name=readers --rw=read --name=writers --rw=write
3245
f80dba8d 3246Fio will condense the thread string as not to take up more space on the command
36214730 3247line than needed. For instance, if you have 10 readers and 10 writers running,
f80dba8d
MT
3248the output would look like this::
3249
9d25d068 3250 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 3251
36214730
SW
3252Note that the status string is displayed in order, so it's possible to tell which of
3253the jobs are currently doing what. In the example above this means that jobs 1--10
3254are readers and 11--20 are writers.
f80dba8d
MT
3255
3256The other values are fairly self explanatory -- number of threads currently
36214730
SW
3257running and doing I/O, the number of currently open files (f=), the estimated
3258completion percentage, the rate of I/O since last check (read speed listed first,
f50fbdda
TK
3259then write speed and optionally trim speed) in terms of bandwidth and IOPS,
3260and time to completion for the current running group. It's impossible to estimate
3261runtime of the following groups (if any).
36214730
SW
3262
3263..
3264 Example output was based on the following:
3265 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
3266 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
3267 --bs=7K --name=Client1 --rw=write
3268
3269When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
3270each thread, group of threads, and disks in that order. For each overall thread (or
3271group) the output looks like::
3272
3273 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
3274 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
3275 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
3276 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
3277 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
3278 clat percentiles (usec):
3279 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
3280 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
3281 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
3282 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
3283 | 99.99th=[78119]
3284 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
3285 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
29092211
VF
3286 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
3287 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
3288 lat (msec) : 100=0.65%
36214730
SW
3289 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
3290 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
3291 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3292 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3293 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
3294 latency : target=0, window=0, percentile=100.00%, depth=8
3295
3296The job name (or first job's name when using :option:`group_reporting`) is printed,
3297along with the group id, count of jobs being aggregated, last error id seen (which
3298is 0 when there are no errors), pid/tid of that thread and the time the job/group
3299completed. Below are the I/O statistics for each data direction performed (showing
3300writes in the example above). In the order listed, they denote:
3301
3302**read/write/trim**
3303 The string before the colon shows the I/O direction the statistics
3304 are for. **IOPS** is the average I/Os performed per second. **BW**
3305 is the average bandwidth rate shown as: value in power of 2 format
3306 (value in power of 10 format). The last two values show: (**total
3307 I/O performed** in power of 2 format / **runtime** of that thread).
f80dba8d
MT
3308
3309**slat**
36214730
SW
3310 Submission latency (**min** being the minimum, **max** being the
3311 maximum, **avg** being the average, **stdev** being the standard
3312 deviation). This is the time it took to submit the I/O. For
3313 sync I/O this row is not displayed as the slat is really the
3314 completion latency (since queue/complete is one operation there).
3315 This value can be in nanoseconds, microseconds or milliseconds ---
3316 fio will choose the most appropriate base and print that (in the
3317 example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
0d237712 3318 latencies are always expressed in microseconds.
f80dba8d
MT
3319
3320**clat**
3321 Completion latency. Same names as slat, this denotes the time from
3322 submission to completion of the I/O pieces. For sync I/O, clat will
3323 usually be equal (or very close) to 0, as the time from submit to
3324 complete is basically just CPU time (I/O has already been done, see slat
3325 explanation).
3326
29092211
VF
3327**lat**
3328 Total latency. Same names as slat and clat, this denotes the time from
3329 when fio created the I/O unit to completion of the I/O operation.
3330
f80dba8d 3331**bw**
36214730
SW
3332 Bandwidth statistics based on samples. Same names as the xlat stats,
3333 but also includes the number of samples taken (**samples**) and an
3334 approximate percentage of total aggregate bandwidth this thread
3335 received in its group (**per**). This last value is only really
3336 useful if the threads in this group are on the same disk, since they
3337 are then competing for disk access.
3338
3339**iops**
3340 IOPS statistics based on samples. Same names as bw.
f80dba8d 3341
29092211
VF
3342**lat (nsec/usec/msec)**
3343 The distribution of I/O completion latencies. This is the time from when
3344 I/O leaves fio and when it gets completed. Unlike the separate
3345 read/write/trim sections above, the data here and in the remaining
3346 sections apply to all I/Os for the reporting group. 250=0.04% means that
3347 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
3348 of the I/Os required 250 to 499us for completion.
3349
f80dba8d
MT
3350**cpu**
3351 CPU usage. User and system time, along with the number of context
3352 switches this thread went through, usage of system and user time, and
3353 finally the number of major and minor page faults. The CPU utilization
3354 numbers are averages for the jobs in that reporting group, while the
23a8e176 3355 context and fault counters are summed.
f80dba8d
MT
3356
3357**IO depths**
a2140525
SW
3358 The distribution of I/O depths over the job lifetime. The numbers are
3359 divided into powers of 2 and each entry covers depths from that value
3360 up to those that are lower than the next entry -- e.g., 16= covers
3361 depths from 16 to 31. Note that the range covered by a depth
3362 distribution entry can be different to the range covered by the
3363 equivalent submit/complete distribution entry.
f80dba8d
MT
3364
3365**IO submit**
3366 How many pieces of I/O were submitting in a single submit call. Each
c60ebc45 3367 entry denotes that amount and below, until the previous entry -- e.g.,
a2140525
SW
3368 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
3369 call. Note that the range covered by a submit distribution entry can
3370 be different to the range covered by the equivalent depth distribution
3371 entry.
f80dba8d
MT
3372
3373**IO complete**
3374 Like the above submit number, but for completions instead.
3375
36214730
SW
3376**IO issued rwt**
3377 The number of read/write/trim requests issued, and how many of them were
3378 short or dropped.
f80dba8d 3379
29092211 3380**IO latency**
ee21ebee 3381 These values are for :option:`latency_target` and related options. When
29092211
VF
3382 these options are engaged, this section describes the I/O depth required
3383 to meet the specified latency target.
71bfa161 3384
36214730
SW
3385..
3386 Example output was based on the following:
3387 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
3388 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
3389 --rate=11M --name=write --rw=write --bs=2k --rate=700k
3390
71bfa161 3391After each client has been listed, the group statistics are printed. They
f80dba8d 3392will look like this::
71bfa161 3393
f80dba8d 3394 Run status group 0 (all jobs):
36214730
SW
3395 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
3396 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
71bfa161 3397
36214730 3398For each data direction it prints:
71bfa161 3399
36214730
SW
3400**bw**
3401 Aggregate bandwidth of threads in this group followed by the
3402 minimum and maximum bandwidth of all the threads in this group.
3403 Values outside of brackets are power-of-2 format and those
3404 within are the equivalent value in a power-of-10 format.
f80dba8d 3405**io**
36214730
SW
3406 Aggregate I/O performed of all threads in this group. The
3407 format is the same as bw.
3408**run**
3409 The smallest and longest runtimes of the threads in this group.
71bfa161 3410
f50fbdda 3411And finally, the disk statistics are printed. This is Linux specific. They will look like this::
71bfa161 3412
f80dba8d
MT
3413 Disk stats (read/write):
3414 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
71bfa161
JA
3415
3416Each value is printed for both reads and writes, with reads first. The
3417numbers denote:
3418
f80dba8d 3419**ios**
c60ebc45 3420 Number of I/Os performed by all groups.
f80dba8d 3421**merge**
007c7be9 3422 Number of merges performed by the I/O scheduler.
f80dba8d
MT
3423**ticks**
3424 Number of ticks we kept the disk busy.
36214730 3425**in_queue**
f80dba8d
MT
3426 Total time spent in the disk queue.
3427**util**
3428 The disk utilization. A value of 100% means we kept the disk
71bfa161
JA
3429 busy constantly, 50% would be a disk idling half of the time.
3430
f80dba8d
MT
3431It is also possible to get fio to dump the current output while it is running,
3432without terminating the job. To do that, send fio the **USR1** signal. You can
3433also get regularly timed dumps by using the :option:`--status-interval`
3434parameter, or by creating a file in :file:`/tmp` named
3435:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
3436current output status.
8423bd11 3437
71bfa161 3438
f80dba8d
MT
3439Terse output
3440------------
71bfa161 3441
f80dba8d
MT
3442For scripted usage where you typically want to generate tables or graphs of the
3443results, fio can output the results in a semicolon separated format. The format
3444is one long line of values, such as::
71bfa161 3445
f80dba8d
MT
3446 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%
3447 A description of this job goes here.
562c2d2f
DN
3448
3449The job description (if provided) follows on a second line.
71bfa161 3450
a7f77fa6
SW
3451To enable terse output, use the :option:`--minimal` or
3452:option:`--output-format`\=terse command line options. The
f80dba8d
MT
3453first value is the version of the terse output format. If the output has to be
3454changed for some reason, this number will be incremented by 1 to signify that
3455change.
6820cb3b 3456
a2c95580 3457Split up, the format is as follows (comments in brackets denote when a
007c7be9 3458field was introduced or whether it's specific to some terse version):
71bfa161 3459
f80dba8d
MT
3460 ::
3461
f50fbdda 3462 terse version, fio version [v3], jobname, groupid, error
f80dba8d
MT
3463
3464 READ status::
3465
3466 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3467 Submission latency: min, max, mean, stdev (usec)
3468 Completion latency: min, max, mean, stdev (usec)
3469 Completion latency percentiles: 20 fields (see below)
3470 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3471 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3472 IOPS [v5]: min, max, mean, stdev, number of samples
f80dba8d
MT
3473
3474 WRITE status:
3475
3476 ::
3477
3478 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3479 Submission latency: min, max, mean, stdev (usec)
247823cc 3480 Completion latency: min, max, mean, stdev (usec)
f80dba8d
MT
3481 Completion latency percentiles: 20 fields (see below)
3482 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3483 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3484 IOPS [v5]: min, max, mean, stdev, number of samples
a2c95580
AH
3485
3486 TRIM status [all but version 3]:
3487
f50fbdda 3488 Fields are similar to READ/WRITE status.
f80dba8d
MT
3489
3490 CPU usage::
3491
3492 user, system, context switches, major faults, minor faults
3493
3494 I/O depths::
3495
3496 <=1, 2, 4, 8, 16, 32, >=64
3497
3498 I/O latencies microseconds::
3499
3500 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
3501
3502 I/O latencies milliseconds::
3503
3504 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
3505
a2c95580 3506 Disk utilization [v3]::
f80dba8d 3507
f50fbdda
TK
3508 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
3509 time spent in queue, disk utilization percentage
f80dba8d
MT
3510
3511 Additional Info (dependent on continue_on_error, default off)::
3512
3513 total # errors, first error code
3514
3515 Additional Info (dependent on description being set)::
3516
3517 Text description
3518
3519Completion latency percentiles can be a grouping of up to 20 sets, so for the
3520terse output fio writes all of them. Each field will look like this::
1db92cb6 3521
f50fbdda 3522 1.00%=6112
1db92cb6 3523
f80dba8d 3524which is the Xth percentile, and the `usec` latency associated with it.
1db92cb6 3525
f50fbdda 3526For `Disk utilization`, all disks used by fio are shown. So for each disk there
f80dba8d 3527will be a disk utilization section.
f2f788dd 3528
2fc26c3d 3529Below is a single line containing short names for each of the fields in the
2831be97 3530minimal output v3, separated by semicolons::
2fc26c3d 3531
f50fbdda 3532 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 3533
25c8b9d7 3534
44c82dba
VF
3535JSON output
3536------------
3537
3538The `json` output format is intended to be both human readable and convenient
3539for automated parsing. For the most part its sections mirror those of the
3540`normal` output. The `runtime` value is reported in msec and the `bw` value is
3541reported in 1024 bytes per second units.
3542
3543
d29c4a91
VF
3544JSON+ output
3545------------
3546
3547The `json+` output format is identical to the `json` output format except that it
3548adds a full dump of the completion latency bins. Each `bins` object contains a
3549set of (key, value) pairs where keys are latency durations and values count how
3550many I/Os had completion latencies of the corresponding duration. For example,
3551consider:
3552
3553 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
3554
3555This data indicates that one I/O required 87,552ns to complete, two I/Os required
3556100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
3557
3558Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
3559json+ output and generates CSV-formatted latency data suitable for plotting.
3560
3561The latency durations actually represent the midpoints of latency intervals.
f50fbdda 3562For details refer to :file:`stat.h`.
d29c4a91
VF
3563
3564
f80dba8d
MT
3565Trace file format
3566-----------------
3567
3568There are two trace file format that you can encounter. The older (v1) format is
3569unsupported since version 1.20-rc3 (March 2008). It will still be described
25c8b9d7
PD
3570below in case that you get an old trace and want to understand it.
3571
3572In any case the trace is a simple text file with a single action per line.
3573
3574
f80dba8d
MT
3575Trace file format v1
3576~~~~~~~~~~~~~~~~~~~~
3577
3578Each line represents a single I/O action in the following format::
3579
3580 rw, offset, length
25c8b9d7 3581
f50fbdda 3582where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
25c8b9d7 3583
22413915 3584This format is not supported in fio versions >= 1.20-rc3.
25c8b9d7 3585
25c8b9d7 3586
f80dba8d
MT
3587Trace file format v2
3588~~~~~~~~~~~~~~~~~~~~
25c8b9d7 3589
f80dba8d
MT
3590The second version of the trace file format was added in fio version 1.17. It
3591allows to access more then one file per trace and has a bigger set of possible
3592file actions.
25c8b9d7 3593
f80dba8d 3594The first line of the trace file has to be::
25c8b9d7 3595
f80dba8d 3596 fio version 2 iolog
25c8b9d7
PD
3597
3598Following this can be lines in two different formats, which are described below.
3599
f80dba8d 3600The file management format::
25c8b9d7 3601
f80dba8d 3602 filename action
25c8b9d7 3603
f50fbdda 3604The `filename` is given as an absolute path. The `action` can be one of these:
25c8b9d7 3605
f80dba8d 3606**add**
f50fbdda 3607 Add the given `filename` to the trace.
f80dba8d 3608**open**
f50fbdda 3609 Open the file with the given `filename`. The `filename` has to have
f80dba8d
MT
3610 been added with the **add** action before.
3611**close**
f50fbdda 3612 Close the file with the given `filename`. The file has to have been
f80dba8d
MT
3613 opened before.
3614
3615
3616The file I/O action format::
3617
3618 filename action offset length
3619
3620The `filename` is given as an absolute path, and has to have been added and
3621opened before it can be used with this format. The `offset` and `length` are
3622given in bytes. The `action` can be one of these:
3623
3624**wait**
3625 Wait for `offset` microseconds. Everything below 100 is discarded.
3626 The time is relative to the previous `wait` statement.
3627**read**
3628 Read `length` bytes beginning from `offset`.
3629**write**
3630 Write `length` bytes beginning from `offset`.
3631**sync**
3632 :manpage:`fsync(2)` the file.
3633**datasync**
3634 :manpage:`fdatasync(2)` the file.
3635**trim**
3636 Trim the given file from the given `offset` for `length` bytes.
3637
3638CPU idleness profiling
3639----------------------
3640
3641In some cases, we want to understand CPU overhead in a test. For example, we
3642test patches for the specific goodness of whether they reduce CPU usage.
3643Fio implements a balloon approach to create a thread per CPU that runs at idle
3644priority, meaning that it only runs when nobody else needs the cpu.
3645By measuring the amount of work completed by the thread, idleness of each CPU
3646can be derived accordingly.
3647
3648An unit work is defined as touching a full page of unsigned characters. Mean and
3649standard deviation of time to complete an unit work is reported in "unit work"
3650section. Options can be chosen to report detailed percpu idleness or overall
3651system idleness by aggregating percpu stats.
3652
3653
3654Verification and triggers
3655-------------------------
3656
3657Fio is usually run in one of two ways, when data verification is done. The first
3658is a normal write job of some sort with verify enabled. When the write phase has
3659completed, fio switches to reads and verifies everything it wrote. The second
3660model is running just the write phase, and then later on running the same job
3661(but with reads instead of writes) to repeat the same I/O patterns and verify
3662the contents. Both of these methods depend on the write phase being completed,
3663as fio otherwise has no idea how much data was written.
3664
3665With verification triggers, fio supports dumping the current write state to
3666local files. Then a subsequent read verify workload can load this state and know
3667exactly where to stop. This is useful for testing cases where power is cut to a
3668server in a managed fashion, for instance.
99b9a85a
JA
3669
3670A verification trigger consists of two things:
3671
f80dba8d
MT
36721) Storing the write state of each job.
36732) Executing a trigger command.
99b9a85a 3674
f80dba8d
MT
3675The write state is relatively small, on the order of hundreds of bytes to single
3676kilobytes. It contains information on the number of completions done, the last X
3677completions, etc.
99b9a85a 3678
f80dba8d
MT
3679A trigger is invoked either through creation ('touch') of a specified file in
3680the system, or through a timeout setting. If fio is run with
9207a0cb 3681:option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
f80dba8d
MT
3682check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
3683will fire off the trigger (thus saving state, and executing the trigger
99b9a85a
JA
3684command).
3685
f80dba8d
MT
3686For client/server runs, there's both a local and remote trigger. If fio is
3687running as a server backend, it will send the job states back to the client for
3688safe storage, then execute the remote trigger, if specified. If a local trigger
3689is specified, the server will still send back the write state, but the client
3690will then execute the trigger.
99b9a85a 3691
f80dba8d
MT
3692Verification trigger example
3693~~~~~~~~~~~~~~~~~~~~~~~~~~~~
99b9a85a 3694
f50fbdda
TK
3695Let's say we want to run a powercut test on the remote Linux machine 'server'.
3696Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
f80dba8d
MT
3697some point during the run, and we'll run this test from the safety or our local
3698machine, 'localbox'. On the server, we'll start the fio backend normally::
99b9a85a 3699
f80dba8d 3700 server# fio --server
99b9a85a 3701
f80dba8d 3702and on the client, we'll fire off the workload::
99b9a85a 3703
f80dba8d 3704 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
99b9a85a 3705
f80dba8d 3706We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
99b9a85a 3707
f80dba8d 3708 echo b > /proc/sysrq-trigger
99b9a85a 3709
f80dba8d
MT
3710on the server once it has received the trigger and sent us the write state. This
3711will work, but it's not **really** cutting power to the server, it's merely
3712abruptly rebooting it. If we have a remote way of cutting power to the server
3713through IPMI or similar, we could do that through a local trigger command
4502cb42 3714instead. Let's assume we have a script that does IPMI reboot of a given hostname,
f80dba8d
MT
3715ipmi-reboot. On localbox, we could then have run fio with a local trigger
3716instead::
99b9a85a 3717
f80dba8d 3718 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
99b9a85a 3719
f80dba8d
MT
3720For this case, fio would wait for the server to send us the write state, then
3721execute ``ipmi-reboot server`` when that happened.
3722
3723Loading verify state
3724~~~~~~~~~~~~~~~~~~~~
3725
4502cb42 3726To load stored write state, a read verification job file must contain the
f80dba8d 3727:option:`verify_state_load` option. If that is set, fio will load the previously
99b9a85a 3728stored state. For a local fio run this is done by loading the files directly,
f80dba8d
MT
3729and on a client/server run, the server backend will ask the client to send the
3730files over and load them from there.
a3ae5b05
JA
3731
3732
f80dba8d
MT
3733Log File Formats
3734----------------
a3ae5b05
JA
3735
3736Fio supports a variety of log file formats, for logging latencies, bandwidth,
3737and IOPS. The logs share a common format, which looks like this:
3738
5a83478f
SW
3739 *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
3740 *offset* (`bytes`)
a3ae5b05 3741
5a83478f 3742*Time* for the log entry is always in milliseconds. The *value* logged depends
a3ae5b05
JA
3743on the type of log, it will be one of the following:
3744
f80dba8d 3745 **Latency log**
168bb587 3746 Value is latency in nsecs
f80dba8d
MT
3747 **Bandwidth log**
3748 Value is in KiB/sec
3749 **IOPS log**
3750 Value is IOPS
3751
3752*Data direction* is one of the following:
3753
3754 **0**
3755 I/O is a READ
3756 **1**
3757 I/O is a WRITE
3758 **2**
3759 I/O is a TRIM
3760
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3761The entry's *block size* is always in bytes. The *offset* is the offset, in bytes,
3762from the start of the file, for that particular I/O. The logging of the offset can be
3763toggled with :option:`log_offset`.
f80dba8d 3764
6fc82095 3765Fio defaults to logging every individual I/O. When IOPS are logged for individual
5a83478f 3766I/Os the *value* entry will always be 1. If windowed logging is enabled through
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3767:option:`log_avg_msec`, fio logs the average values over the specified period of time.
3768If windowed logging is enabled and :option:`log_max_value` is set, then fio logs
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3769maximum values in that window instead of averages. Since *data direction*, *block
3770size* and *offset* are per-I/O values, if windowed logging is enabled they
3771aren't applicable and will be 0.
f80dba8d 3772
b8f7e412 3773Client/Server
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3774-------------
3775
3776Normally fio is invoked as a stand-alone application on the machine where the
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3777I/O workload should be generated. However, the backend and frontend of fi