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71bfa161 JA |
1 | Table of contents |
2 | ----------------- | |
3 | ||
4 | 1. Overview | |
5 | 2. How fio works | |
6 | 3. Running fio | |
7 | 4. Job file format | |
8 | 5. Detailed list of parameters | |
9 | 6. Normal output | |
10 | 7. Terse output | |
25c8b9d7 | 11 | 8. Trace file format |
43f09da1 | 12 | 9. CPU idleness profiling |
29dbd1e5 | 13 | 10. Verification and triggers |
a3ae5b05 JA |
14 | 11. Log File Formats |
15 | ||
71bfa161 JA |
16 | |
17 | 1.0 Overview and history | |
18 | ------------------------ | |
19 | fio was originally written to save me the hassle of writing special test | |
20 | case programs when I wanted to test a specific workload, either for | |
21 | performance reasons or to find/reproduce a bug. The process of writing | |
22 | such a test app can be tiresome, especially if you have to do it often. | |
23 | Hence I needed a tool that would be able to simulate a given io workload | |
24 | without resorting to writing a tailored test case again and again. | |
25 | ||
26 | A test work load is difficult to define, though. There can be any number | |
27 | of processes or threads involved, and they can each be using their own | |
28 | way of generating io. You could have someone dirtying large amounts of | |
29 | memory in an memory mapped file, or maybe several threads issuing | |
30 | reads using asynchronous io. fio needed to be flexible enough to | |
31 | simulate both of these cases, and many more. | |
32 | ||
33 | 2.0 How fio works | |
34 | ----------------- | |
35 | The first step in getting fio to simulate a desired io workload, is | |
36 | writing a job file describing that specific setup. A job file may contain | |
37 | any number of threads and/or files - the typical contents of the job file | |
38 | is a global section defining shared parameters, and one or more job | |
39 | sections describing the jobs involved. When run, fio parses this file | |
40 | and sets everything up as described. If we break down a job from top to | |
41 | bottom, it contains the following basic parameters: | |
42 | ||
43 | IO type Defines the io pattern issued to the file(s). | |
44 | We may only be reading sequentially from this | |
45 | file(s), or we may be writing randomly. Or even | |
46 | mixing reads and writes, sequentially or randomly. | |
47 | ||
48 | Block size In how large chunks are we issuing io? This may be | |
49 | a single value, or it may describe a range of | |
50 | block sizes. | |
51 | ||
52 | IO size How much data are we going to be reading/writing. | |
53 | ||
54 | IO engine How do we issue io? We could be memory mapping the | |
55 | file, we could be using regular read/write, we | |
d0ff85df | 56 | could be using splice, async io, syslet, or even |
71bfa161 JA |
57 | SG (SCSI generic sg). |
58 | ||
6c219763 | 59 | IO depth If the io engine is async, how large a queuing |
71bfa161 JA |
60 | depth do we want to maintain? |
61 | ||
62 | IO type Should we be doing buffered io, or direct/raw io? | |
63 | ||
64 | Num files How many files are we spreading the workload over. | |
65 | ||
66 | Num threads How many threads or processes should we spread | |
67 | this workload over. | |
66c098b8 | 68 | |
71bfa161 JA |
69 | The above are the basic parameters defined for a workload, in addition |
70 | there's a multitude of parameters that modify other aspects of how this | |
71 | job behaves. | |
72 | ||
73 | ||
74 | 3.0 Running fio | |
75 | --------------- | |
76 | See the README file for command line parameters, there are only a few | |
77 | of them. | |
78 | ||
79 | Running fio is normally the easiest part - you just give it the job file | |
80 | (or job files) as parameters: | |
81 | ||
82 | $ fio job_file | |
83 | ||
84 | and it will start doing what the job_file tells it to do. You can give | |
85 | more than one job file on the command line, fio will serialize the running | |
86 | of those files. Internally that is the same as using the 'stonewall' | |
550b1db6 | 87 | parameter described in the parameter section. |
71bfa161 | 88 | |
b4692828 JA |
89 | If the job file contains only one job, you may as well just give the |
90 | parameters on the command line. The command line parameters are identical | |
91 | to the job parameters, with a few extra that control global parameters | |
92 | (see README). For example, for the job file parameter iodepth=2, the | |
c2b1e753 JA |
93 | mirror command line option would be --iodepth 2 or --iodepth=2. You can |
94 | also use the command line for giving more than one job entry. For each | |
95 | --name option that fio sees, it will start a new job with that name. | |
96 | Command line entries following a --name entry will apply to that job, | |
97 | until there are no more entries or a new --name entry is seen. This is | |
98 | similar to the job file options, where each option applies to the current | |
99 | job until a new [] job entry is seen. | |
b4692828 | 100 | |
71bfa161 JA |
101 | fio does not need to run as root, except if the files or devices specified |
102 | in the job section requires that. Some other options may also be restricted, | |
6c219763 | 103 | such as memory locking, io scheduler switching, and decreasing the nice value. |
71bfa161 JA |
104 | |
105 | ||
106 | 4.0 Job file format | |
107 | ------------------- | |
108 | As previously described, fio accepts one or more job files describing | |
109 | what it is supposed to do. The job file format is the classic ini file, | |
110 | where the names enclosed in [] brackets define the job name. You are free | |
111 | to use any ascii name you want, except 'global' which has special meaning. | |
112 | A global section sets defaults for the jobs described in that file. A job | |
113 | may override a global section parameter, and a job file may even have | |
114 | several global sections if so desired. A job is only affected by a global | |
65db0851 JA |
115 | section residing above it. If the first character in a line is a ';' or a |
116 | '#', the entire line is discarded as a comment. | |
71bfa161 | 117 | |
3c54bc46 | 118 | So let's look at a really simple job file that defines two processes, each |
b22989b9 | 119 | randomly reading from a 128MB file. |
71bfa161 JA |
120 | |
121 | ; -- start job file -- | |
122 | [global] | |
123 | rw=randread | |
124 | size=128m | |
125 | ||
126 | [job1] | |
127 | ||
128 | [job2] | |
129 | ||
130 | ; -- end job file -- | |
131 | ||
132 | As you can see, the job file sections themselves are empty as all the | |
133 | described parameters are shared. As no filename= option is given, fio | |
c2b1e753 JA |
134 | makes up a filename for each of the jobs as it sees fit. On the command |
135 | line, this job would look as follows: | |
136 | ||
137 | $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2 | |
138 | ||
71bfa161 | 139 | |
3c54bc46 | 140 | Let's look at an example that has a number of processes writing randomly |
71bfa161 JA |
141 | to files. |
142 | ||
143 | ; -- start job file -- | |
144 | [random-writers] | |
145 | ioengine=libaio | |
146 | iodepth=4 | |
147 | rw=randwrite | |
148 | bs=32k | |
149 | direct=0 | |
150 | size=64m | |
151 | numjobs=4 | |
152 | ||
153 | ; -- end job file -- | |
154 | ||
155 | Here we have no global section, as we only have one job defined anyway. | |
156 | We want to use async io here, with a depth of 4 for each file. We also | |
b22989b9 | 157 | increased the buffer size used to 32KB and define numjobs to 4 to |
71bfa161 | 158 | fork 4 identical jobs. The result is 4 processes each randomly writing |
b22989b9 | 159 | to their own 64MB file. Instead of using the above job file, you could |
b4692828 JA |
160 | have given the parameters on the command line. For this case, you would |
161 | specify: | |
162 | ||
163 | $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4 | |
71bfa161 | 164 | |
df5ad464 AK |
165 | When fio is utilized as a basis of any reasonably large test suite, it might be |
166 | desirable to share a set of standardized settings across multiple job files. | |
167 | Instead of copy/pasting such settings, any section may pull in an external | |
168 | .fio file with 'include filename' directive, as in the following example: | |
169 | ||
170 | ; -- start job file including.fio -- | |
171 | [global] | |
172 | filename=/tmp/test | |
173 | filesize=1m | |
174 | include glob-include.fio | |
175 | ||
176 | [test] | |
177 | rw=randread | |
178 | bs=4k | |
179 | time_based=1 | |
180 | runtime=10 | |
181 | include test-include.fio | |
182 | ; -- end job file including.fio -- | |
183 | ||
184 | ; -- start job file glob-include.fio -- | |
185 | thread=1 | |
186 | group_reporting=1 | |
187 | ; -- end job file glob-include.fio -- | |
188 | ||
189 | ; -- start job file test-include.fio -- | |
190 | ioengine=libaio | |
191 | iodepth=4 | |
192 | ; -- end job file test-include.fio -- | |
193 | ||
194 | Settings pulled into a section apply to that section only (except global | |
195 | section). Include directives may be nested in that any included file may | |
73568e1b JA |
196 | contain further include directive(s). Include files may not contain [] |
197 | sections. | |
df5ad464 AK |
198 | |
199 | ||
74929ac2 JA |
200 | 4.1 Environment variables |
201 | ------------------------- | |
202 | ||
3c54bc46 | 203 | fio also supports environment variable expansion in job files. Any |
4fbe1860 | 204 | sub-string of the form "${VARNAME}" as part of an option value (in other |
3c54bc46 AC |
205 | words, on the right of the `='), will be expanded to the value of the |
206 | environment variable called VARNAME. If no such environment variable | |
207 | is defined, or VARNAME is the empty string, the empty string will be | |
208 | substituted. | |
209 | ||
210 | As an example, let's look at a sample fio invocation and job file: | |
211 | ||
212 | $ SIZE=64m NUMJOBS=4 fio jobfile.fio | |
213 | ||
214 | ; -- start job file -- | |
215 | [random-writers] | |
216 | rw=randwrite | |
217 | size=${SIZE} | |
218 | numjobs=${NUMJOBS} | |
219 | ; -- end job file -- | |
220 | ||
221 | This will expand to the following equivalent job file at runtime: | |
222 | ||
223 | ; -- start job file -- | |
224 | [random-writers] | |
225 | rw=randwrite | |
226 | size=64m | |
227 | numjobs=4 | |
228 | ; -- end job file -- | |
229 | ||
71bfa161 JA |
230 | fio ships with a few example job files, you can also look there for |
231 | inspiration. | |
232 | ||
74929ac2 JA |
233 | 4.2 Reserved keywords |
234 | --------------------- | |
235 | ||
236 | Additionally, fio has a set of reserved keywords that will be replaced | |
237 | internally with the appropriate value. Those keywords are: | |
238 | ||
239 | $pagesize The architecture page size of the running system | |
240 | $mb_memory Megabytes of total memory in the system | |
241 | $ncpus Number of online available CPUs | |
242 | ||
243 | These can be used on the command line or in the job file, and will be | |
244 | automatically substituted with the current system values when the job | |
892a6ffc JA |
245 | is run. Simple math is also supported on these keywords, so you can |
246 | perform actions like: | |
247 | ||
248 | size=8*$mb_memory | |
249 | ||
250 | and get that properly expanded to 8 times the size of memory in the | |
251 | machine. | |
74929ac2 | 252 | |
71bfa161 JA |
253 | |
254 | 5.0 Detailed list of parameters | |
255 | ------------------------------- | |
256 | ||
257 | This section describes in details each parameter associated with a job. | |
258 | Some parameters take an option of a given type, such as an integer or | |
d59aa780 JA |
259 | a string. Anywhere a numeric value is required, an arithmetic expression |
260 | may be used, provided it is surrounded by parentheses. Supported operators | |
261 | are: | |
262 | ||
263 | addition (+) | |
264 | subtraction (-) | |
265 | multiplication (*) | |
266 | division (/) | |
267 | modulus (%) | |
268 | exponentiation (^) | |
269 | ||
270 | For time values in expressions, units are microseconds by default. This is | |
271 | different than for time values not in expressions (not enclosed in | |
272 | parentheses). The following types are used: | |
71bfa161 JA |
273 | |
274 | str String. This is a sequence of alpha characters. | |
b09da8fa | 275 | time Integer with possible time suffix. In seconds unless otherwise |
e417fd66 | 276 | specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds, |
0de5b26f JA |
277 | minutes, and hours, and accepts 'ms' (or 'msec') for milliseconds, |
278 | and 'us' (or 'usec') for microseconds. | |
b09da8fa JA |
279 | int SI integer. A whole number value, which may contain a suffix |
280 | describing the base of the number. Accepted suffixes are k/m/g/t/p, | |
281 | meaning kilo, mega, giga, tera, and peta. The suffix is not case | |
57fc29fa JA |
282 | sensitive, and you may also include trailing 'b' (eg 'kb' is the same |
283 | as 'k'). So if you want to specify 4096, you could either write | |
b09da8fa | 284 | out '4096' or just give 4k. The suffixes signify base 2 values, so |
57fc29fa JA |
285 | 1024 is 1k and 1024k is 1m and so on, unless the suffix is explicitly |
286 | set to a base 10 value using 'kib', 'mib', 'gib', etc. If that is the | |
287 | case, then 1000 is used as the multiplier. This can be handy for | |
288 | disks, since manufacturers generally use base 10 values when listing | |
289 | the capacity of a drive. If the option accepts an upper and lower | |
290 | range, use a colon ':' or minus '-' to separate such values. May also | |
291 | include a prefix to indicate numbers base. If 0x is used, the number | |
292 | is assumed to be hexadecimal. See irange. | |
71bfa161 JA |
293 | bool Boolean. Usually parsed as an integer, however only defined for |
294 | true and false (1 and 0). | |
b09da8fa | 295 | irange Integer range with suffix. Allows value range to be given, such |
bf9a3edb | 296 | as 1024-4096. A colon may also be used as the separator, eg |
0c9baf91 JA |
297 | 1k:4k. If the option allows two sets of ranges, they can be |
298 | specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see | |
f7fa2653 | 299 | int. |
83349190 | 300 | float_list A list of floating numbers, separated by a ':' character. |
71bfa161 JA |
301 | |
302 | With the above in mind, here follows the complete list of fio job | |
303 | parameters. | |
304 | ||
305 | name=str ASCII name of the job. This may be used to override the | |
306 | name printed by fio for this job. Otherwise the job | |
c2b1e753 | 307 | name is used. On the command line this parameter has the |
6c219763 | 308 | special purpose of also signaling the start of a new |
c2b1e753 | 309 | job. |
71bfa161 | 310 | |
9cc8cb91 AK |
311 | wait_for=str Specifies the name of the already defined job to wait |
312 | for. Single waitee name only may be specified. If set, the job | |
313 | won't be started until all workers of the waitee job are done. | |
314 | ||
315 | Wait_for operates on the job name basis, so there are a few | |
316 | limitations. First, the waitee must be defined prior to the | |
317 | waiter job (meaning no forward references). Second, if a job | |
318 | is being referenced as a waitee, it must have a unique name | |
319 | (no duplicate waitees). | |
320 | ||
61697c37 JA |
321 | description=str Text description of the job. Doesn't do anything except |
322 | dump this text description when this job is run. It's | |
323 | not parsed. | |
324 | ||
3776041e | 325 | directory=str Prefix filenames with this directory. Used to place files |
67445b63 JA |
326 | in a different location than "./". See the 'filename' option |
327 | for escaping certain characters. | |
71bfa161 JA |
328 | |
329 | filename=str Fio normally makes up a filename based on the job name, | |
330 | thread number, and file number. If you want to share | |
331 | files between threads in a job or several jobs, specify | |
ed92ac0c | 332 | a filename for each of them to override the default. If |
414c2a3e | 333 | the ioengine used is 'net', the filename is the host, port, |
0fd666bf | 334 | and protocol to use in the format of =host,port,protocol. |
414c2a3e JA |
335 | See ioengine=net for more. If the ioengine is file based, you |
336 | can specify a number of files by separating the names with a | |
337 | ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb | |
338 | as the two working files, you would use | |
30a4588a JA |
339 | filename=/dev/sda:/dev/sdb. On Windows, disk devices are |
340 | accessed as \\.\PhysicalDrive0 for the first device, | |
341 | \\.\PhysicalDrive1 for the second etc. Note: Windows and | |
342 | FreeBSD prevent write access to areas of the disk containing | |
343 | in-use data (e.g. filesystems). | |
344 | If the wanted filename does need to include a colon, then | |
345 | escape that with a '\' character. For instance, if the filename | |
346 | is "/dev/dsk/foo@3,0:c", then you would use | |
347 | filename="/dev/dsk/foo@3,0\:c". '-' is a reserved name, meaning | |
348 | stdin or stdout. Which of the two depends on the read/write | |
349 | direction set. | |
71bfa161 | 350 | |
de98bd30 JA |
351 | filename_format=str |
352 | If sharing multiple files between jobs, it is usually necessary | |
353 | to have fio generate the exact names that you want. By default, | |
354 | fio will name a file based on the default file format | |
355 | specification of jobname.jobnumber.filenumber. With this | |
356 | option, that can be customized. Fio will recognize and replace | |
357 | the following keywords in this string: | |
358 | ||
359 | $jobname | |
360 | The name of the worker thread or process. | |
361 | ||
362 | $jobnum | |
363 | The incremental number of the worker thread or | |
364 | process. | |
365 | ||
366 | $filenum | |
367 | The incremental number of the file for that worker | |
368 | thread or process. | |
369 | ||
370 | To have dependent jobs share a set of files, this option can | |
371 | be set to have fio generate filenames that are shared between | |
372 | the two. For instance, if testfiles.$filenum is specified, | |
373 | file number 4 for any job will be named testfiles.4. The | |
374 | default of $jobname.$jobnum.$filenum will be used if | |
375 | no other format specifier is given. | |
376 | ||
bbf6b540 JA |
377 | opendir=str Tell fio to recursively add any file it can find in this |
378 | directory and down the file system tree. | |
379 | ||
3776041e | 380 | lockfile=str Fio defaults to not locking any files before it does |
4d4e80f2 JA |
381 | IO to them. If a file or file descriptor is shared, fio |
382 | can serialize IO to that file to make the end result | |
383 | consistent. This is usual for emulating real workloads that | |
384 | share files. The lock modes are: | |
385 | ||
386 | none No locking. The default. | |
387 | exclusive Only one thread/process may do IO, | |
388 | excluding all others. | |
389 | readwrite Read-write locking on the file. Many | |
390 | readers may access the file at the | |
391 | same time, but writes get exclusive | |
392 | access. | |
393 | ||
d3aad8f2 | 394 | readwrite=str |
71bfa161 JA |
395 | rw=str Type of io pattern. Accepted values are: |
396 | ||
397 | read Sequential reads | |
398 | write Sequential writes | |
399 | randwrite Random writes | |
400 | randread Random reads | |
10b023db | 401 | rw,readwrite Sequential mixed reads and writes |
71bfa161 | 402 | randrw Random mixed reads and writes |
82a90686 JA |
403 | trimwrite Mixed trims and writes. Blocks will be |
404 | trimmed first, then written to. | |
71bfa161 JA |
405 | |
406 | For the mixed io types, the default is to split them 50/50. | |
407 | For certain types of io the result may still be skewed a bit, | |
211097b2 | 408 | since the speed may be different. It is possible to specify |
38dad62d | 409 | a number of IO's to do before getting a new offset, this is |
892ea9bd | 410 | done by appending a ':<nr>' to the end of the string given. |
38dad62d | 411 | For a random read, it would look like 'rw=randread:8' for |
059b0802 | 412 | passing in an offset modifier with a value of 8. If the |
ddb754db | 413 | suffix is used with a sequential IO pattern, then the value |
059b0802 JA |
414 | specified will be added to the generated offset for each IO. |
415 | For instance, using rw=write:4k will skip 4k for every | |
416 | write. It turns sequential IO into sequential IO with holes. | |
417 | See the 'rw_sequencer' option. | |
38dad62d JA |
418 | |
419 | rw_sequencer=str If an offset modifier is given by appending a number to | |
420 | the rw=<str> line, then this option controls how that | |
421 | number modifies the IO offset being generated. Accepted | |
422 | values are: | |
423 | ||
424 | sequential Generate sequential offset | |
425 | identical Generate the same offset | |
426 | ||
427 | 'sequential' is only useful for random IO, where fio would | |
428 | normally generate a new random offset for every IO. If you | |
429 | append eg 8 to randread, you would get a new random offset for | |
211097b2 JA |
430 | every 8 IO's. The result would be a seek for only every 8 |
431 | IO's, instead of for every IO. Use rw=randread:8 to specify | |
38dad62d JA |
432 | that. As sequential IO is already sequential, setting |
433 | 'sequential' for that would not result in any differences. | |
434 | 'identical' behaves in a similar fashion, except it sends | |
435 | the same offset 8 number of times before generating a new | |
436 | offset. | |
71bfa161 | 437 | |
90fef2d1 JA |
438 | kb_base=int The base unit for a kilobyte. The defacto base is 2^10, 1024. |
439 | Storage manufacturers like to use 10^3 or 1000 as a base | |
440 | ten unit instead, for obvious reasons. Allow values are | |
441 | 1024 or 1000, with 1024 being the default. | |
442 | ||
771e58be JA |
443 | unified_rw_reporting=bool Fio normally reports statistics on a per |
444 | data direction basis, meaning that read, write, and trim are | |
445 | accounted and reported separately. If this option is set, | |
446 | the fio will sum the results and report them as "mixed" | |
447 | instead. | |
448 | ||
ee738499 JA |
449 | randrepeat=bool For random IO workloads, seed the generator in a predictable |
450 | way so that results are repeatable across repetitions. | |
40fe5e7b | 451 | Defaults to true. |
ee738499 | 452 | |
04778baf JA |
453 | randseed=int Seed the random number generators based on this seed value, to |
454 | be able to control what sequence of output is being generated. | |
455 | If not set, the random sequence depends on the randrepeat | |
456 | setting. | |
457 | ||
a596f047 EG |
458 | fallocate=str Whether pre-allocation is performed when laying down files. |
459 | Accepted values are: | |
460 | ||
461 | none Do not pre-allocate space | |
462 | posix Pre-allocate via posix_fallocate() | |
463 | keep Pre-allocate via fallocate() with | |
464 | FALLOC_FL_KEEP_SIZE set | |
465 | 0 Backward-compatible alias for 'none' | |
466 | 1 Backward-compatible alias for 'posix' | |
467 | ||
468 | May not be available on all supported platforms. 'keep' is only | |
469 | available on Linux.If using ZFS on Solaris this must be set to | |
470 | 'none' because ZFS doesn't support it. Default: 'posix'. | |
7bc8c2cf | 471 | |
d2f3ac35 JA |
472 | fadvise_hint=bool By default, fio will use fadvise() to advise the kernel |
473 | on what IO patterns it is likely to issue. Sometimes you | |
474 | want to test specific IO patterns without telling the | |
475 | kernel about it, in which case you can disable this option. | |
476 | If set, fio will use POSIX_FADV_SEQUENTIAL for sequential | |
477 | IO and POSIX_FADV_RANDOM for random IO. | |
478 | ||
37659335 JA |
479 | fadvise_stream=int Notify the kernel what write stream ID to place these |
480 | writes under. Only supported on Linux. Note, this option | |
481 | may change going forward. | |
482 | ||
f7fa2653 | 483 | size=int The total size of file io for this job. Fio will run until |
7616cafe | 484 | this many bytes has been transferred, unless runtime is |
a4d3b4db JA |
485 | limited by other options (such as 'runtime', for instance, |
486 | or increased/decreased by 'io_size'). Unless specific nrfiles | |
487 | and filesize options are given, fio will divide this size | |
488 | between the available files specified by the job. If not set, | |
489 | fio will use the full size of the given files or devices. | |
490 | If the files do not exist, size must be given. It is also | |
491 | possible to give size as a percentage between 1 and 100. If | |
492 | size=20% is given, fio will use 20% of the full size of the | |
493 | given files or devices. | |
494 | ||
495 | io_size=int | |
77731b29 JA |
496 | io_limit=int Normally fio operates within the region set by 'size', which |
497 | means that the 'size' option sets both the region and size of | |
498 | IO to be performed. Sometimes that is not what you want. With | |
499 | this option, it is possible to define just the amount of IO | |
500 | that fio should do. For instance, if 'size' is set to 20G and | |
a4d3b4db JA |
501 | 'io_size' is set to 5G, fio will perform IO within the first |
502 | 20G but exit when 5G have been done. The opposite is also | |
503 | possible - if 'size' is set to 20G, and 'io_size' is set to | |
504 | 40G, then fio will do 40G of IO within the 0..20G region. | |
77731b29 | 505 | |
f7fa2653 | 506 | filesize=int Individual file sizes. May be a range, in which case fio |
9c60ce64 JA |
507 | will select sizes for files at random within the given range |
508 | and limited to 'size' in total (if that is given). If not | |
509 | given, each created file is the same size. | |
510 | ||
bedc9dc2 JA |
511 | file_append=bool Perform IO after the end of the file. Normally fio will |
512 | operate within the size of a file. If this option is set, then | |
513 | fio will append to the file instead. This has identical | |
0aae4ce7 JA |
514 | behavior to setting offset to the size of a file. This option |
515 | is ignored on non-regular files. | |
bedc9dc2 | 516 | |
74586c1e JA |
517 | fill_device=bool |
518 | fill_fs=bool Sets size to something really large and waits for ENOSPC (no | |
aa31f1f1 | 519 | space left on device) as the terminating condition. Only makes |
de98bd30 | 520 | sense with sequential write. For a read workload, the mount |
4f12432e JA |
521 | point will be filled first then IO started on the result. This |
522 | option doesn't make sense if operating on a raw device node, | |
523 | since the size of that is already known by the file system. | |
524 | Additionally, writing beyond end-of-device will not return | |
525 | ENOSPC there. | |
aa31f1f1 | 526 | |
f7fa2653 JA |
527 | blocksize=int |
528 | bs=int The block size used for the io units. Defaults to 4k. Values | |
529 | can be given for both read and writes. If a single int is | |
530 | given, it will apply to both. If a second int is specified | |
f90eff5a | 531 | after a comma, it will apply to writes only. In other words, |
d9472271 JA |
532 | the format is either bs=read_and_write or bs=read,write,trim. |
533 | bs=4k,8k will thus use 4k blocks for reads, 8k blocks for | |
534 | writes, and 8k for trims. You can terminate the list with | |
535 | a trailing comma. bs=4k,8k, would use the default value for | |
536 | trims.. If you only wish to set the write size, you | |
787f7e95 JA |
537 | can do so by passing an empty read size - bs=,8k will set |
538 | 8k for writes and leave the read default value. | |
a00735e6 | 539 | |
2b7a01d0 JA |
540 | blockalign=int |
541 | ba=int At what boundary to align random IO offsets. Defaults to | |
542 | the same as 'blocksize' the minimum blocksize given. | |
543 | Minimum alignment is typically 512b for using direct IO, | |
544 | though it usually depends on the hardware block size. This | |
545 | option is mutually exclusive with using a random map for | |
546 | files, so it will turn off that option. | |
547 | ||
d3aad8f2 | 548 | blocksize_range=irange |
71bfa161 JA |
549 | bsrange=irange Instead of giving a single block size, specify a range |
550 | and fio will mix the issued io block sizes. The issued | |
551 | io unit will always be a multiple of the minimum value | |
f90eff5a JA |
552 | given (also see bs_unaligned). Applies to both reads and |
553 | writes, however a second range can be given after a comma. | |
554 | See bs=. | |
a00735e6 | 555 | |
564ca972 JA |
556 | bssplit=str Sometimes you want even finer grained control of the |
557 | block sizes issued, not just an even split between them. | |
558 | This option allows you to weight various block sizes, | |
559 | so that you are able to define a specific amount of | |
560 | block sizes issued. The format for this option is: | |
561 | ||
562 | bssplit=blocksize/percentage:blocksize/percentage | |
563 | ||
564 | for as many block sizes as needed. So if you want to define | |
565 | a workload that has 50% 64k blocks, 10% 4k blocks, and | |
566 | 40% 32k blocks, you would write: | |
567 | ||
568 | bssplit=4k/10:64k/50:32k/40 | |
569 | ||
570 | Ordering does not matter. If the percentage is left blank, | |
571 | fio will fill in the remaining values evenly. So a bssplit | |
572 | option like this one: | |
573 | ||
574 | bssplit=4k/50:1k/:32k/ | |
575 | ||
576 | would have 50% 4k ios, and 25% 1k and 32k ios. The percentages | |
577 | always add up to 100, if bssplit is given a range that adds | |
578 | up to more, it will error out. | |
579 | ||
720e84ad JA |
580 | bssplit also supports giving separate splits to reads and |
581 | writes. The format is identical to what bs= accepts. You | |
582 | have to separate the read and write parts with a comma. So | |
583 | if you want a workload that has 50% 2k reads and 50% 4k reads, | |
584 | while having 90% 4k writes and 10% 8k writes, you would | |
585 | specify: | |
586 | ||
892ea9bd | 587 | bssplit=2k/50:4k/50,4k/90:8k/10 |
720e84ad | 588 | |
d3aad8f2 | 589 | blocksize_unaligned |
690adba3 JA |
590 | bs_unaligned If this option is given, any byte size value within bsrange |
591 | may be used as a block range. This typically wont work with | |
592 | direct IO, as that normally requires sector alignment. | |
71bfa161 | 593 | |
6aca9b3d JA |
594 | bs_is_seq_rand If this option is set, fio will use the normal read,write |
595 | blocksize settings as sequential,random instead. Any random | |
596 | read or write will use the WRITE blocksize settings, and any | |
597 | sequential read or write will use the READ blocksize setting. | |
598 | ||
e9459e5a JA |
599 | zero_buffers If this option is given, fio will init the IO buffers to |
600 | all zeroes. The default is to fill them with random data. | |
601 | ||
5973cafb JA |
602 | refill_buffers If this option is given, fio will refill the IO buffers |
603 | on every submit. The default is to only fill it at init | |
604 | time and reuse that data. Only makes sense if zero_buffers | |
41ccd845 JA |
605 | isn't specified, naturally. If data verification is enabled, |
606 | refill_buffers is also automatically enabled. | |
5973cafb | 607 | |
fd68418e JA |
608 | scramble_buffers=bool If refill_buffers is too costly and the target is |
609 | using data deduplication, then setting this option will | |
610 | slightly modify the IO buffer contents to defeat normal | |
611 | de-dupe attempts. This is not enough to defeat more clever | |
612 | block compression attempts, but it will stop naive dedupe of | |
613 | blocks. Default: true. | |
614 | ||
c5751c62 JA |
615 | buffer_compress_percentage=int If this is set, then fio will attempt to |
616 | provide IO buffer content (on WRITEs) that compress to | |
617 | the specified level. Fio does this by providing a mix of | |
d1af2894 JA |
618 | random data and a fixed pattern. The fixed pattern is either |
619 | zeroes, or the pattern specified by buffer_pattern. If the | |
620 | pattern option is used, it might skew the compression ratio | |
621 | slightly. Note that this is per block size unit, for file/disk | |
622 | wide compression level that matches this setting, you'll also | |
623 | want to set refill_buffers. | |
c5751c62 JA |
624 | |
625 | buffer_compress_chunk=int See buffer_compress_percentage. This | |
626 | setting allows fio to manage how big the ranges of random | |
627 | data and zeroed data is. Without this set, fio will | |
628 | provide buffer_compress_percentage of blocksize random | |
629 | data, followed by the remaining zeroed. With this set | |
630 | to some chunk size smaller than the block size, fio can | |
631 | alternate random and zeroed data throughout the IO | |
632 | buffer. | |
633 | ||
5c94b008 JA |
634 | buffer_pattern=str If set, fio will fill the io buffers with this |
635 | pattern. If not set, the contents of io buffers is defined by | |
636 | the other options related to buffer contents. The setting can | |
637 | be any pattern of bytes, and can be prefixed with 0x for hex | |
638 | values. It may also be a string, where the string must then | |
61b9861d RP |
639 | be wrapped with "", e.g.: |
640 | ||
641 | buffer_pattern="abcd" | |
642 | or | |
643 | buffer_pattern=-12 | |
644 | or | |
645 | buffer_pattern=0xdeadface | |
646 | ||
647 | Also you can combine everything together in any order: | |
648 | buffer_pattern=0xdeadface"abcd"-12 | |
5c94b008 JA |
649 | |
650 | dedupe_percentage=int If set, fio will generate this percentage of | |
651 | identical buffers when writing. These buffers will be | |
652 | naturally dedupable. The contents of the buffers depend on | |
653 | what other buffer compression settings have been set. It's | |
654 | possible to have the individual buffers either fully | |
655 | compressible, or not at all. This option only controls the | |
656 | distribution of unique buffers. | |
ce35b1ec | 657 | |
71bfa161 JA |
658 | nrfiles=int Number of files to use for this job. Defaults to 1. |
659 | ||
390b1537 JA |
660 | openfiles=int Number of files to keep open at the same time. Defaults to |
661 | the same as nrfiles, can be set smaller to limit the number | |
662 | simultaneous opens. | |
663 | ||
5af1c6f3 JA |
664 | file_service_type=str Defines how fio decides which file from a job to |
665 | service next. The following types are defined: | |
666 | ||
667 | random Just choose a file at random. | |
668 | ||
669 | roundrobin Round robin over open files. This | |
670 | is the default. | |
671 | ||
a086c257 JA |
672 | sequential Finish one file before moving on to |
673 | the next. Multiple files can still be | |
674 | open depending on 'openfiles'. | |
675 | ||
1907dbc6 JA |
676 | The string can have a number appended, indicating how |
677 | often to switch to a new file. So if option random:4 is | |
678 | given, fio will switch to a new random file after 4 ios | |
679 | have been issued. | |
680 | ||
71bfa161 JA |
681 | ioengine=str Defines how the job issues io to the file. The following |
682 | types are defined: | |
683 | ||
684 | sync Basic read(2) or write(2) io. lseek(2) is | |
685 | used to position the io location. | |
686 | ||
a31041ea | 687 | psync Basic pread(2) or pwrite(2) io. |
688 | ||
e05af9e5 | 689 | vsync Basic readv(2) or writev(2) IO. |
1d2af02a | 690 | |
a46c5e01 JA |
691 | psyncv Basic preadv(2) or pwritev(2) IO. |
692 | ||
15d182aa JA |
693 | libaio Linux native asynchronous io. Note that Linux |
694 | may only support queued behaviour with | |
695 | non-buffered IO (set direct=1 or buffered=0). | |
de890a1e | 696 | This engine defines engine specific options. |
71bfa161 JA |
697 | |
698 | posixaio glibc posix asynchronous io. | |
699 | ||
417f0068 JA |
700 | solarisaio Solaris native asynchronous io. |
701 | ||
03e20d68 BC |
702 | windowsaio Windows native asynchronous io. |
703 | ||
71bfa161 JA |
704 | mmap File is memory mapped and data copied |
705 | to/from using memcpy(3). | |
706 | ||
707 | splice splice(2) is used to transfer the data and | |
708 | vmsplice(2) to transfer data from user | |
709 | space to the kernel. | |
710 | ||
d0ff85df JA |
711 | syslet-rw Use the syslet system calls to make |
712 | regular read/write async. | |
713 | ||
71bfa161 | 714 | sg SCSI generic sg v3 io. May either be |
6c219763 | 715 | synchronous using the SG_IO ioctl, or if |
71bfa161 JA |
716 | the target is an sg character device |
717 | we use read(2) and write(2) for asynchronous | |
718 | io. | |
719 | ||
a94ea28b JA |
720 | null Doesn't transfer any data, just pretends |
721 | to. This is mainly used to exercise fio | |
722 | itself and for debugging/testing purposes. | |
723 | ||
ed92ac0c | 724 | net Transfer over the network to given host:port. |
de890a1e SL |
725 | Depending on the protocol used, the hostname, |
726 | port, listen and filename options are used to | |
727 | specify what sort of connection to make, while | |
728 | the protocol option determines which protocol | |
729 | will be used. | |
730 | This engine defines engine specific options. | |
ed92ac0c | 731 | |
9cce02e8 JA |
732 | netsplice Like net, but uses splice/vmsplice to |
733 | map data and send/receive. | |
de890a1e | 734 | This engine defines engine specific options. |
9cce02e8 | 735 | |
53aec0a4 | 736 | cpuio Doesn't transfer any data, but burns CPU |
ba0fbe10 JA |
737 | cycles according to the cpuload= and |
738 | cpucycle= options. Setting cpuload=85 | |
739 | will cause that job to do nothing but burn | |
36ecec83 GP |
740 | 85% of the CPU. In case of SMP machines, |
741 | use numjobs=<no_of_cpu> to get desired CPU | |
742 | usage, as the cpuload only loads a single | |
743 | CPU at the desired rate. | |
ba0fbe10 | 744 | |
e9a1806f JA |
745 | guasi The GUASI IO engine is the Generic Userspace |
746 | Asyncronous Syscall Interface approach | |
747 | to async IO. See | |
748 | ||
749 | http://www.xmailserver.org/guasi-lib.html | |
750 | ||
751 | for more info on GUASI. | |
752 | ||
21b8aee8 | 753 | rdma The RDMA I/O engine supports both RDMA |
eb52fa3f BVA |
754 | memory semantics (RDMA_WRITE/RDMA_READ) and |
755 | channel semantics (Send/Recv) for the | |
756 | InfiniBand, RoCE and iWARP protocols. | |
21b8aee8 | 757 | |
b861be9f JA |
758 | falloc IO engine that does regular fallocate to |
759 | simulate data transfer as fio ioengine. | |
760 | DDIR_READ does fallocate(,mode = keep_size,) | |
761 | DDIR_WRITE does fallocate(,mode = 0) | |
762 | DDIR_TRIM does fallocate(,mode = punch_hole) | |
d54fce84 DM |
763 | |
764 | e4defrag IO engine that does regular EXT4_IOC_MOVE_EXT | |
b861be9f JA |
765 | ioctls to simulate defragment activity in |
766 | request to DDIR_WRITE event | |
767 | ||
768 | rbd IO engine supporting direct access to Ceph | |
769 | Rados Block Devices (RBD) via librbd without | |
770 | the need to use the kernel rbd driver. This | |
771 | ioengine defines engine specific options. | |
772 | ||
773 | gfapi Using Glusterfs libgfapi sync interface to | |
774 | direct access to Glusterfs volumes without | |
775 | options. | |
776 | ||
777 | gfapi_async Using Glusterfs libgfapi async interface | |
778 | to direct access to Glusterfs volumes without | |
779 | having to go through FUSE. This ioengine | |
780 | defines engine specific options. | |
0981fd71 | 781 | |
b74e419e | 782 | libhdfs Read and write through Hadoop (HDFS). |
a3f001f5 | 783 | This engine interprets offsets a little |
b74e419e MM |
784 | differently. In HDFS, files once created |
785 | cannot be modified. So random writes are not | |
786 | possible. To imitate this, libhdfs engine | |
a3f001f5 FB |
787 | creates bunch of small files, and engine will |
788 | pick a file out of those files based on the | |
789 | offset enerated by fio backend. Each jobs uses | |
790 | it's own connection to HDFS. | |
1b10477b | 791 | |
65fa28ca DE |
792 | mtd Read, write and erase an MTD character device |
793 | (e.g., /dev/mtd0). Discards are treated as | |
794 | erases. Depending on the underlying device | |
795 | type, the I/O may have to go in a certain | |
796 | pattern, e.g., on NAND, writing sequentially | |
797 | to erase blocks and discarding before | |
798 | overwriting. The writetrim mode works well | |
799 | for this constraint. | |
800 | ||
8a7bd877 JA |
801 | external Prefix to specify loading an external |
802 | IO engine object file. Append the engine | |
803 | filename, eg ioengine=external:/tmp/foo.o | |
804 | to load ioengine foo.o in /tmp. | |
805 | ||
71bfa161 JA |
806 | iodepth=int This defines how many io units to keep in flight against |
807 | the file. The default is 1 for each file defined in this | |
808 | job, can be overridden with a larger value for higher | |
ee72ca09 JA |
809 | concurrency. Note that increasing iodepth beyond 1 will not |
810 | affect synchronous ioengines (except for small degress when | |
9b836561 | 811 | verify_async is in use). Even async engines may impose OS |
ee72ca09 JA |
812 | restrictions causing the desired depth not to be achieved. |
813 | This may happen on Linux when using libaio and not setting | |
814 | direct=1, since buffered IO is not async on that OS. Keep an | |
815 | eye on the IO depth distribution in the fio output to verify | |
816 | that the achieved depth is as expected. Default: 1. | |
71bfa161 | 817 | |
4950421a | 818 | iodepth_batch_submit=int |
cb5ab512 | 819 | iodepth_batch=int This defines how many pieces of IO to submit at once. |
89e820f6 JA |
820 | It defaults to 1 which means that we submit each IO |
821 | as soon as it is available, but can be raised to submit | |
e63a0b2f RP |
822 | bigger batches of IO at the time. If it is set to 0 the iodepth |
823 | value will be used. | |
cb5ab512 | 824 | |
82407585 | 825 | iodepth_batch_complete_min=int |
4950421a JA |
826 | iodepth_batch_complete=int This defines how many pieces of IO to retrieve |
827 | at once. It defaults to 1 which means that we'll ask | |
828 | for a minimum of 1 IO in the retrieval process from | |
829 | the kernel. The IO retrieval will go on until we | |
830 | hit the limit set by iodepth_low. If this variable is | |
831 | set to 0, then fio will always check for completed | |
832 | events before queuing more IO. This helps reduce | |
833 | IO latency, at the cost of more retrieval system calls. | |
834 | ||
82407585 RP |
835 | iodepth_batch_complete_max=int This defines maximum pieces of IO to |
836 | retrieve at once. This variable should be used along with | |
837 | iodepth_batch_complete_min=int variable, specifying the range | |
838 | of min and max amount of IO which should be retrieved. By default | |
839 | it is equal to iodepth_batch_complete_min value. | |
840 | ||
841 | Example #1: | |
842 | ||
843 | iodepth_batch_complete_min=1 | |
844 | iodepth_batch_complete_max=<iodepth> | |
845 | ||
846 | which means that we will retrieve at leat 1 IO and up to the | |
847 | whole submitted queue depth. If none of IO has been completed | |
848 | yet, we will wait. | |
849 | ||
850 | Example #2: | |
851 | ||
852 | iodepth_batch_complete_min=0 | |
853 | iodepth_batch_complete_max=<iodepth> | |
854 | ||
855 | which means that we can retrieve up to the whole submitted | |
856 | queue depth, but if none of IO has been completed yet, we will | |
857 | NOT wait and immediately exit the system call. In this example | |
858 | we simply do polling. | |
859 | ||
e916b390 JA |
860 | iodepth_low=int The low water mark indicating when to start filling |
861 | the queue again. Defaults to the same as iodepth, meaning | |
862 | that fio will attempt to keep the queue full at all times. | |
863 | If iodepth is set to eg 16 and iodepth_low is set to 4, then | |
864 | after fio has filled the queue of 16 requests, it will let | |
865 | the depth drain down to 4 before starting to fill it again. | |
866 | ||
1ad01bd1 JA |
867 | io_submit_mode=str This option controls how fio submits the IO to |
868 | the IO engine. The default is 'inline', which means that the | |
869 | fio job threads submit and reap IO directly. If set to | |
870 | 'offload', the job threads will offload IO submission to a | |
871 | dedicated pool of IO threads. This requires some coordination | |
872 | and thus has a bit of extra overhead, especially for lower | |
873 | queue depth IO where it can increase latencies. The benefit | |
874 | is that fio can manage submission rates independently of | |
875 | the device completion rates. This avoids skewed latency | |
876 | reporting if IO gets back up on the device side (the | |
877 | coordinated omission problem). | |
878 | ||
71bfa161 | 879 | direct=bool If value is true, use non-buffered io. This is usually |
9b836561 | 880 | O_DIRECT. Note that ZFS on Solaris doesn't support direct io. |
93bcfd20 | 881 | On Windows the synchronous ioengines don't support direct io. |
76a43db4 | 882 | |
d01612f3 CM |
883 | atomic=bool If value is true, attempt to use atomic direct IO. Atomic |
884 | writes are guaranteed to be stable once acknowledged by | |
885 | the operating system. Only Linux supports O_ATOMIC right | |
886 | now. | |
887 | ||
76a43db4 JA |
888 | buffered=bool If value is true, use buffered io. This is the opposite |
889 | of the 'direct' option. Defaults to true. | |
71bfa161 | 890 | |
f7fa2653 | 891 | offset=int Start io at the given offset in the file. The data before |
71bfa161 JA |
892 | the given offset will not be touched. This effectively |
893 | caps the file size at real_size - offset. | |
894 | ||
214ac7e0 | 895 | offset_increment=int If this is provided, then the real offset becomes |
69bdd6ba JH |
896 | offset + offset_increment * thread_number, where the thread |
897 | number is a counter that starts at 0 and is incremented for | |
898 | each sub-job (i.e. when numjobs option is specified). This | |
899 | option is useful if there are several jobs which are intended | |
900 | to operate on a file in parallel disjoint segments, with | |
901 | even spacing between the starting points. | |
214ac7e0 | 902 | |
ddf24e42 JA |
903 | number_ios=int Fio will normally perform IOs until it has exhausted the size |
904 | of the region set by size=, or if it exhaust the allocated | |
905 | time (or hits an error condition). With this setting, the | |
906 | range/size can be set independently of the number of IOs to | |
907 | perform. When fio reaches this number, it will exit normally | |
be3fec7d JA |
908 | and report status. Note that this does not extend the amount |
909 | of IO that will be done, it will only stop fio if this | |
910 | condition is met before other end-of-job criteria. | |
ddf24e42 | 911 | |
71bfa161 JA |
912 | fsync=int If writing to a file, issue a sync of the dirty data |
913 | for every number of blocks given. For example, if you give | |
914 | 32 as a parameter, fio will sync the file for every 32 | |
915 | writes issued. If fio is using non-buffered io, we may | |
916 | not sync the file. The exception is the sg io engine, which | |
6c219763 | 917 | synchronizes the disk cache anyway. |
71bfa161 | 918 | |
e76b1da4 | 919 | fdatasync=int Like fsync= but uses fdatasync() to only sync data and not |
5f9099ea | 920 | metadata blocks. |
37db59d6 JA |
921 | In FreeBSD and Windows there is no fdatasync(), this falls back |
922 | to using fsync() | |
5f9099ea | 923 | |
e76b1da4 JA |
924 | sync_file_range=str:val Use sync_file_range() for every 'val' number of |
925 | write operations. Fio will track range of writes that | |
926 | have happened since the last sync_file_range() call. 'str' | |
927 | can currently be one or more of: | |
928 | ||
929 | wait_before SYNC_FILE_RANGE_WAIT_BEFORE | |
930 | write SYNC_FILE_RANGE_WRITE | |
931 | wait_after SYNC_FILE_RANGE_WAIT_AFTER | |
932 | ||
933 | So if you do sync_file_range=wait_before,write:8, fio would | |
934 | use SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE for | |
935 | every 8 writes. Also see the sync_file_range(2) man page. | |
936 | This option is Linux specific. | |
937 | ||
5036fc1e JA |
938 | overwrite=bool If true, writes to a file will always overwrite existing |
939 | data. If the file doesn't already exist, it will be | |
940 | created before the write phase begins. If the file exists | |
941 | and is large enough for the specified write phase, nothing | |
942 | will be done. | |
71bfa161 | 943 | |
dbd11ead | 944 | end_fsync=bool If true, fsync file contents when a write stage has completed. |
71bfa161 | 945 | |
ebb1415f JA |
946 | fsync_on_close=bool If true, fio will fsync() a dirty file on close. |
947 | This differs from end_fsync in that it will happen on every | |
948 | file close, not just at the end of the job. | |
949 | ||
71bfa161 JA |
950 | rwmixread=int How large a percentage of the mix should be reads. |
951 | ||
952 | rwmixwrite=int How large a percentage of the mix should be writes. If both | |
953 | rwmixread and rwmixwrite is given and the values do not add | |
954 | up to 100%, the latter of the two will be used to override | |
c35dd7a6 JA |
955 | the first. This may interfere with a given rate setting, |
956 | if fio is asked to limit reads or writes to a certain rate. | |
957 | If that is the case, then the distribution may be skewed. | |
71bfa161 | 958 | |
92d42d69 JA |
959 | random_distribution=str:float By default, fio will use a completely uniform |
960 | random distribution when asked to perform random IO. Sometimes | |
961 | it is useful to skew the distribution in specific ways, | |
962 | ensuring that some parts of the data is more hot than others. | |
963 | fio includes the following distribution models: | |
964 | ||
965 | random Uniform random distribution | |
966 | zipf Zipf distribution | |
967 | pareto Pareto distribution | |
8116fd24 | 968 | gauss Normal (guassian) distribution |
e0a04ac1 | 969 | zoned Zoned random distribution |
92d42d69 JA |
970 | |
971 | When using a zipf or pareto distribution, an input value | |
972 | is also needed to define the access pattern. For zipf, this | |
973 | is the zipf theta. For pareto, it's the pareto power. Fio | |
974 | includes a test program, genzipf, that can be used visualize | |
975 | what the given input values will yield in terms of hit rates. | |
976 | If you wanted to use zipf with a theta of 1.2, you would use | |
977 | random_distribution=zipf:1.2 as the option. If a non-uniform | |
8116fd24 JA |
978 | model is used, fio will disable use of the random map. For |
979 | the gauss distribution, a normal deviation is supplied as | |
980 | a value between 0 and 100. | |
92d42d69 | 981 | |
e0a04ac1 JA |
982 | For a zoned distribution, fio supports specifying percentages |
983 | of IO access that should fall within what range of the file or | |
984 | device. For example, given a criteria of: | |
985 | ||
986 | 60% of accesses should be to the first 10% | |
987 | 30% of accesses should be to the next 20% | |
988 | 8% of accesses should be to to the next 30% | |
989 | 2% of accesses should be to the next 40% | |
990 | ||
991 | we can define that through zoning of the random accesses. For | |
992 | the above example, the user would do: | |
993 | ||
994 | random_distribution=zoned:60/10:30/20:8/30:2/40 | |
995 | ||
996 | similarly to how bssplit works for setting ranges and | |
997 | percentages of block sizes. Like bssplit, it's possible to | |
998 | specify separate zones for reads, writes, and trims. If just | |
999 | one set is given, it'll apply to all of them. | |
1000 | ||
211c9b89 JA |
1001 | percentage_random=int For a random workload, set how big a percentage should |
1002 | be random. This defaults to 100%, in which case the workload | |
1003 | is fully random. It can be set from anywhere from 0 to 100. | |
1004 | Setting it to 0 would make the workload fully sequential. Any | |
1005 | setting in between will result in a random mix of sequential | |
d9472271 JA |
1006 | and random IO, at the given percentages. It is possible to |
1007 | set different values for reads, writes, and trim. To do so, | |
1008 | simply use a comma separated list. See blocksize. | |
211c9b89 | 1009 | |
bb8895e0 JA |
1010 | norandommap Normally fio will cover every block of the file when doing |
1011 | random IO. If this option is given, fio will just get a | |
1012 | new random offset without looking at past io history. This | |
1013 | means that some blocks may not be read or written, and that | |
83da8fbf JE |
1014 | some blocks may be read/written more than once. If this option |
1015 | is used with verify= and multiple blocksizes (via bsrange=), | |
1016 | only intact blocks are verified, i.e., partially-overwritten | |
1017 | blocks are ignored. | |
bb8895e0 | 1018 | |
0408c206 JA |
1019 | softrandommap=bool See norandommap. If fio runs with the random block map |
1020 | enabled and it fails to allocate the map, if this option is | |
1021 | set it will continue without a random block map. As coverage | |
1022 | will not be as complete as with random maps, this option is | |
2b386d25 JA |
1023 | disabled by default. |
1024 | ||
e8b1961d JA |
1025 | random_generator=str Fio supports the following engines for generating |
1026 | IO offsets for random IO: | |
1027 | ||
1028 | tausworthe Strong 2^88 cycle random number generator | |
1029 | lfsr Linear feedback shift register generator | |
c3546b53 JA |
1030 | tausworthe64 Strong 64-bit 2^258 cycle random number |
1031 | generator | |
e8b1961d JA |
1032 | |
1033 | Tausworthe is a strong random number generator, but it | |
1034 | requires tracking on the side if we want to ensure that | |
1035 | blocks are only read or written once. LFSR guarantees | |
1036 | that we never generate the same offset twice, and it's | |
1037 | also less computationally expensive. It's not a true | |
1038 | random generator, however, though for IO purposes it's | |
1039 | typically good enough. LFSR only works with single | |
1040 | block sizes, not with workloads that use multiple block | |
1041 | sizes. If used with such a workload, fio may read or write | |
3bb85e84 JA |
1042 | some blocks multiple times. The default value is tausworthe, |
1043 | unless the required space exceeds 2^32 blocks. If it does, | |
1044 | then tausworthe64 is selected automatically. | |
43f09da1 | 1045 | |
71bfa161 JA |
1046 | nice=int Run the job with the given nice value. See man nice(2). |
1047 | ||
1048 | prio=int Set the io priority value of this job. Linux limits us to | |
1049 | a positive value between 0 and 7, with 0 being the highest. | |
1050 | See man ionice(1). | |
1051 | ||
1052 | prioclass=int Set the io priority class. See man ionice(1). | |
1053 | ||
1054 | thinktime=int Stall the job x microseconds after an io has completed before | |
1055 | issuing the next. May be used to simulate processing being | |
48097d5c JA |
1056 | done by an application. See thinktime_blocks and |
1057 | thinktime_spin. | |
1058 | ||
1059 | thinktime_spin=int | |
1060 | Only valid if thinktime is set - pretend to spend CPU time | |
1061 | doing something with the data received, before falling back | |
1062 | to sleeping for the rest of the period specified by | |
1063 | thinktime. | |
9c1f7434 | 1064 | |
4d01ece6 | 1065 | thinktime_blocks=int |
9c1f7434 JA |
1066 | Only valid if thinktime is set - control how many blocks |
1067 | to issue, before waiting 'thinktime' usecs. If not set, | |
1068 | defaults to 1 which will make fio wait 'thinktime' usecs | |
4d01ece6 JA |
1069 | after every block. This effectively makes any queue depth |
1070 | setting redundant, since no more than 1 IO will be queued | |
1071 | before we have to complete it and do our thinktime. In | |
1072 | other words, this setting effectively caps the queue depth | |
1073 | if the latter is larger. | |
71bfa161 | 1074 | |
581e7141 | 1075 | rate=int Cap the bandwidth used by this job. The number is in bytes/sec, |
b09da8fa | 1076 | the normal suffix rules apply. You can use rate=500k to limit |
581e7141 JA |
1077 | reads and writes to 500k each, or you can specify read and |
1078 | writes separately. Using rate=1m,500k would limit reads to | |
1079 | 1MB/sec and writes to 500KB/sec. Capping only reads or | |
1080 | writes can be done with rate=,500k or rate=500k,. The former | |
1081 | will only limit writes (to 500KB/sec), the latter will only | |
1082 | limit reads. | |
71bfa161 | 1083 | |
6d428bcd | 1084 | rate_min=int Tell fio to do whatever it can to maintain at least this |
4e991c23 | 1085 | bandwidth. Failing to meet this requirement, will cause |
581e7141 JA |
1086 | the job to exit. The same format as rate is used for |
1087 | read vs write separation. | |
4e991c23 JA |
1088 | |
1089 | rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same | |
1090 | as rate, just specified independently of bandwidth. If the | |
1091 | job is given a block size range instead of a fixed value, | |
581e7141 | 1092 | the smallest block size is used as the metric. The same format |
de8f6de9 | 1093 | as rate is used for read vs write separation. |
4e991c23 JA |
1094 | |
1095 | rate_iops_min=int If fio doesn't meet this rate of IO, it will cause | |
581e7141 | 1096 | the job to exit. The same format as rate is used for read vs |
de8f6de9 | 1097 | write separation. |
71bfa161 | 1098 | |
6de65959 JA |
1099 | rate_process=str This option controls how fio manages rated IO |
1100 | submissions. The default is 'linear', which submits IO in a | |
1101 | linear fashion with fixed delays between IOs that gets | |
1102 | adjusted based on IO completion rates. If this is set to | |
1103 | 'poisson', fio will submit IO based on a more real world | |
1104 | random request flow, known as the Poisson process | |
5d02b083 JA |
1105 | (https://en.wikipedia.org/wiki/Poisson_process). The lambda |
1106 | will be 10^6 / IOPS for the given workload. | |
e7b24047 | 1107 | |
3e260a46 JA |
1108 | latency_target=int If set, fio will attempt to find the max performance |
1109 | point that the given workload will run at while maintaining a | |
1110 | latency below this target. The values is given in microseconds. | |
1111 | See latency_window and latency_percentile | |
1112 | ||
1113 | latency_window=int Used with latency_target to specify the sample window | |
1114 | that the job is run at varying queue depths to test the | |
1115 | performance. The value is given in microseconds. | |
1116 | ||
1117 | latency_percentile=float The percentage of IOs that must fall within the | |
1118 | criteria specified by latency_target and latency_window. If not | |
1119 | set, this defaults to 100.0, meaning that all IOs must be equal | |
1120 | or below to the value set by latency_target. | |
1121 | ||
15501535 JA |
1122 | max_latency=int If set, fio will exit the job if it exceeds this maximum |
1123 | latency. It will exit with an ETIME error. | |
1124 | ||
6d428bcd | 1125 | rate_cycle=int Average bandwidth for 'rate' and 'rate_min' over this number |
6c219763 | 1126 | of milliseconds. |
71bfa161 JA |
1127 | |
1128 | cpumask=int Set the CPU affinity of this job. The parameter given is a | |
a08bc17f JA |
1129 | bitmask of allowed CPU's the job may run on. So if you want |
1130 | the allowed CPUs to be 1 and 5, you would pass the decimal | |
1131 | value of (1 << 1 | 1 << 5), or 34. See man | |
7dbb6eba | 1132 | sched_setaffinity(2). This may not work on all supported |
b0ea08ce JA |
1133 | operating systems or kernel versions. This option doesn't |
1134 | work well for a higher CPU count than what you can store in | |
1135 | an integer mask, so it can only control cpus 1-32. For | |
1136 | boxes with larger CPU counts, use cpus_allowed. | |
71bfa161 | 1137 | |
d2e268b0 JA |
1138 | cpus_allowed=str Controls the same options as cpumask, but it allows a text |
1139 | setting of the permitted CPUs instead. So to use CPUs 1 and | |
62a7273d JA |
1140 | 5, you would specify cpus_allowed=1,5. This options also |
1141 | allows a range of CPUs. Say you wanted a binding to CPUs | |
1142 | 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15. | |
d2e268b0 | 1143 | |
c2acfbac JA |
1144 | cpus_allowed_policy=str Set the policy of how fio distributes the CPUs |
1145 | specified by cpus_allowed or cpumask. Two policies are | |
1146 | supported: | |
1147 | ||
1148 | shared All jobs will share the CPU set specified. | |
1149 | split Each job will get a unique CPU from the CPU set. | |
1150 | ||
1151 | 'shared' is the default behaviour, if the option isn't | |
ada083cd JA |
1152 | specified. If split is specified, then fio will will assign |
1153 | one cpu per job. If not enough CPUs are given for the jobs | |
1154 | listed, then fio will roundrobin the CPUs in the set. | |
c2acfbac | 1155 | |
d0b937ed YR |
1156 | numa_cpu_nodes=str Set this job running on spcified NUMA nodes' CPUs. The |
1157 | arguments allow comma delimited list of cpu numbers, | |
1158 | A-B ranges, or 'all'. Note, to enable numa options support, | |
67bf9823 | 1159 | fio must be built on a system with libnuma-dev(el) installed. |
d0b937ed YR |
1160 | |
1161 | numa_mem_policy=str Set this job's memory policy and corresponding NUMA | |
1162 | nodes. Format of the argements: | |
1163 | <mode>[:<nodelist>] | |
1164 | `mode' is one of the following memory policy: | |
1165 | default, prefer, bind, interleave, local | |
1166 | For `default' and `local' memory policy, no node is | |
1167 | needed to be specified. | |
1168 | For `prefer', only one node is allowed. | |
1169 | For `bind' and `interleave', it allow comma delimited | |
1170 | list of numbers, A-B ranges, or 'all'. | |
1171 | ||
e417fd66 | 1172 | startdelay=time Start this job the specified number of seconds after fio |
71bfa161 JA |
1173 | has started. Only useful if the job file contains several |
1174 | jobs, and you want to delay starting some jobs to a certain | |
1175 | time. | |
1176 | ||
e417fd66 | 1177 | runtime=time Tell fio to terminate processing after the specified number |
71bfa161 JA |
1178 | of seconds. It can be quite hard to determine for how long |
1179 | a specified job will run, so this parameter is handy to | |
1180 | cap the total runtime to a given time. | |
1181 | ||
cf4464ca | 1182 | time_based If set, fio will run for the duration of the runtime |
bf9a3edb | 1183 | specified even if the file(s) are completely read or |
cf4464ca JA |
1184 | written. It will simply loop over the same workload |
1185 | as many times as the runtime allows. | |
1186 | ||
e417fd66 | 1187 | ramp_time=time If set, fio will run the specified workload for this amount |
721938ae JA |
1188 | of time before logging any performance numbers. Useful for |
1189 | letting performance settle before logging results, thus | |
b29ee5b3 JA |
1190 | minimizing the runtime required for stable results. Note |
1191 | that the ramp_time is considered lead in time for a job, | |
1192 | thus it will increase the total runtime if a special timeout | |
1193 | or runtime is specified. | |
721938ae | 1194 | |
71bfa161 JA |
1195 | invalidate=bool Invalidate the buffer/page cache parts for this file prior |
1196 | to starting io. Defaults to true. | |
1197 | ||
1198 | sync=bool Use sync io for buffered writes. For the majority of the | |
1199 | io engines, this means using O_SYNC. | |
1200 | ||
d3aad8f2 | 1201 | iomem=str |
71bfa161 JA |
1202 | mem=str Fio can use various types of memory as the io unit buffer. |
1203 | The allowed values are: | |
1204 | ||
1205 | malloc Use memory from malloc(3) as the buffers. | |
1206 | ||
1207 | shm Use shared memory as the buffers. Allocated | |
1208 | through shmget(2). | |
1209 | ||
74b025b0 JA |
1210 | shmhuge Same as shm, but use huge pages as backing. |
1211 | ||
313cb206 JA |
1212 | mmap Use mmap to allocate buffers. May either be |
1213 | anonymous memory, or can be file backed if | |
1214 | a filename is given after the option. The | |
1215 | format is mem=mmap:/path/to/file. | |
71bfa161 | 1216 | |
d0bdaf49 JA |
1217 | mmaphuge Use a memory mapped huge file as the buffer |
1218 | backing. Append filename after mmaphuge, ala | |
1219 | mem=mmaphuge:/hugetlbfs/file | |
1220 | ||
09c782bb JA |
1221 | mmapshared Same as mmap, but use a MMAP_SHARED |
1222 | mapping. | |
1223 | ||
71bfa161 | 1224 | The area allocated is a function of the maximum allowed |
5394ae5f JA |
1225 | bs size for the job, multiplied by the io depth given. Note |
1226 | that for shmhuge and mmaphuge to work, the system must have | |
1227 | free huge pages allocated. This can normally be checked | |
1228 | and set by reading/writing /proc/sys/vm/nr_hugepages on a | |
b22989b9 | 1229 | Linux system. Fio assumes a huge page is 4MB in size. So |
5394ae5f JA |
1230 | to calculate the number of huge pages you need for a given |
1231 | job file, add up the io depth of all jobs (normally one unless | |
1232 | iodepth= is used) and multiply by the maximum bs set. Then | |
1233 | divide that number by the huge page size. You can see the | |
1234 | size of the huge pages in /proc/meminfo. If no huge pages | |
1235 | are allocated by having a non-zero number in nr_hugepages, | |
56bb17f2 | 1236 | using mmaphuge or shmhuge will fail. Also see hugepage-size. |
5394ae5f JA |
1237 | |
1238 | mmaphuge also needs to have hugetlbfs mounted and the file | |
1239 | location should point there. So if it's mounted in /huge, | |
1240 | you would use mem=mmaphuge:/huge/somefile. | |
71bfa161 | 1241 | |
d529ee19 JA |
1242 | iomem_align=int This indiciates the memory alignment of the IO memory buffers. |
1243 | Note that the given alignment is applied to the first IO unit | |
1244 | buffer, if using iodepth the alignment of the following buffers | |
1245 | are given by the bs used. In other words, if using a bs that is | |
1246 | a multiple of the page sized in the system, all buffers will | |
1247 | be aligned to this value. If using a bs that is not page | |
1248 | aligned, the alignment of subsequent IO memory buffers is the | |
1249 | sum of the iomem_align and bs used. | |
1250 | ||
f7fa2653 | 1251 | hugepage-size=int |
56bb17f2 | 1252 | Defines the size of a huge page. Must at least be equal |
b22989b9 | 1253 | to the system setting, see /proc/meminfo. Defaults to 4MB. |
c51074e7 JA |
1254 | Should probably always be a multiple of megabytes, so using |
1255 | hugepage-size=Xm is the preferred way to set this to avoid | |
1256 | setting a non-pow-2 bad value. | |
56bb17f2 | 1257 | |
71bfa161 JA |
1258 | exitall When one job finishes, terminate the rest. The default is |
1259 | to wait for each job to finish, sometimes that is not the | |
1260 | desired action. | |
1261 | ||
f9cafb12 JA |
1262 | exitall_on_error When one job finishes in error, terminate the rest. The |
1263 | default is to wait for each job to finish. | |
1264 | ||
71bfa161 | 1265 | bwavgtime=int Average the calculated bandwidth over the given time. Value |
6c219763 | 1266 | is specified in milliseconds. |
71bfa161 | 1267 | |
c8eeb9df JA |
1268 | iopsavgtime=int Average the calculated IOPS over the given time. Value |
1269 | is specified in milliseconds. | |
1270 | ||
71bfa161 JA |
1271 | create_serialize=bool If true, serialize the file creating for the jobs. |
1272 | This may be handy to avoid interleaving of data | |
1273 | files, which may greatly depend on the filesystem | |
1274 | used and even the number of processors in the system. | |
1275 | ||
1276 | create_fsync=bool fsync the data file after creation. This is the | |
1277 | default. | |
1278 | ||
814452bd JA |
1279 | create_on_open=bool Don't pre-setup the files for IO, just create open() |
1280 | when it's time to do IO to that file. | |
1281 | ||
25460cf6 JA |
1282 | create_only=bool If true, fio will only run the setup phase of the job. |
1283 | If files need to be laid out or updated on disk, only | |
1284 | that will be done. The actual job contents are not | |
1285 | executed. | |
1286 | ||
2378826d JA |
1287 | allow_file_create=bool If true, fio is permitted to create files as part |
1288 | of its workload. This is the default behavior. If this | |
1289 | option is false, then fio will error out if the files it | |
1290 | needs to use don't already exist. Default: true. | |
1291 | ||
e81ecca3 JA |
1292 | allow_mounted_write=bool If this isn't set, fio will abort jobs that |
1293 | are destructive (eg that write) to what appears to be a | |
1294 | mounted device or partition. This should help catch creating | |
1295 | inadvertently destructive tests, not realizing that the test | |
1296 | will destroy data on the mounted file system. Default: false. | |
1297 | ||
afad68f7 | 1298 | pre_read=bool If this is given, files will be pre-read into memory before |
34f1c044 JA |
1299 | starting the given IO operation. This will also clear |
1300 | the 'invalidate' flag, since it is pointless to pre-read | |
9c0d2241 JA |
1301 | and then drop the cache. This will only work for IO engines |
1302 | that are seekable, since they allow you to read the same data | |
1303 | multiple times. Thus it will not work on eg network or splice | |
1304 | IO. | |
afad68f7 | 1305 | |
e545a6ce | 1306 | unlink=bool Unlink the job files when done. Not the default, as repeated |
bf9a3edb JA |
1307 | runs of that job would then waste time recreating the file |
1308 | set again and again. | |
71bfa161 JA |
1309 | |
1310 | loops=int Run the specified number of iterations of this job. Used | |
1311 | to repeat the same workload a given number of times. Defaults | |
1312 | to 1. | |
1313 | ||
62167762 JC |
1314 | verify_only Do not perform specified workload---only verify data still |
1315 | matches previous invocation of this workload. This option | |
1316 | allows one to check data multiple times at a later date | |
1317 | without overwriting it. This option makes sense only for | |
1318 | workloads that write data, and does not support workloads | |
1319 | with the time_based option set. | |
1320 | ||
68e1f29a | 1321 | do_verify=bool Run the verify phase after a write phase. Only makes sense if |
e84c73a8 SL |
1322 | verify is set. Defaults to 1. |
1323 | ||
71bfa161 | 1324 | verify=str If writing to a file, fio can verify the file contents |
b638d82f RP |
1325 | after each iteration of the job. Each verification method also implies |
1326 | verification of special header, which is written to the beginning of | |
1327 | each block. This header also includes meta information, like offset | |
1328 | of the block, block number, timestamp when block was written, etc. | |
1329 | verify=str can be combined with verify_pattern=str option. | |
1330 | The allowed values are: | |
71bfa161 JA |
1331 | |
1332 | md5 Use an md5 sum of the data area and store | |
1333 | it in the header of each block. | |
1334 | ||
17dc34df JA |
1335 | crc64 Use an experimental crc64 sum of the data |
1336 | area and store it in the header of each | |
1337 | block. | |
1338 | ||
bac39e0e JA |
1339 | crc32c Use a crc32c sum of the data area and store |
1340 | it in the header of each block. | |
1341 | ||
3845591f | 1342 | crc32c-intel Use hardware assisted crc32c calcuation |
0539d758 JA |
1343 | provided on SSE4.2 enabled processors. Falls |
1344 | back to regular software crc32c, if not | |
1345 | supported by the system. | |
3845591f | 1346 | |
71bfa161 JA |
1347 | crc32 Use a crc32 sum of the data area and store |
1348 | it in the header of each block. | |
1349 | ||
969f7ed3 JA |
1350 | crc16 Use a crc16 sum of the data area and store |
1351 | it in the header of each block. | |
1352 | ||
17dc34df JA |
1353 | crc7 Use a crc7 sum of the data area and store |
1354 | it in the header of each block. | |
1355 | ||
844ea602 JA |
1356 | xxhash Use xxhash as the checksum function. Generally |
1357 | the fastest software checksum that fio | |
1358 | supports. | |
1359 | ||
cd14cc10 JA |
1360 | sha512 Use sha512 as the checksum function. |
1361 | ||
1362 | sha256 Use sha256 as the checksum function. | |
1363 | ||
7c353ceb JA |
1364 | sha1 Use optimized sha1 as the checksum function. |
1365 | ||
b638d82f RP |
1366 | meta This option is deprecated, since now meta information is |
1367 | included in generic verification header and meta verification | |
1368 | happens by default. For detailed information see the description | |
1369 | of the verify=str setting. This option is kept because of | |
1370 | compatibility's sake with old configurations. Do not use it. | |
7437ee87 | 1371 | |
59245381 JA |
1372 | pattern Verify a strict pattern. Normally fio includes |
1373 | a header with some basic information and | |
1374 | checksumming, but if this option is set, only | |
1375 | the specific pattern set with 'verify_pattern' | |
1376 | is verified. | |
1377 | ||
36690c9b JA |
1378 | null Only pretend to verify. Useful for testing |
1379 | internals with ioengine=null, not for much | |
1380 | else. | |
1381 | ||
6c219763 | 1382 | This option can be used for repeated burn-in tests of a |
71bfa161 | 1383 | system to make sure that the written data is also |
b892dc08 JA |
1384 | correctly read back. If the data direction given is |
1385 | a read or random read, fio will assume that it should | |
1386 | verify a previously written file. If the data direction | |
1387 | includes any form of write, the verify will be of the | |
1388 | newly written data. | |
71bfa161 | 1389 | |
160b966d JA |
1390 | verifysort=bool If set, fio will sort written verify blocks when it deems |
1391 | it faster to read them back in a sorted manner. This is | |
1392 | often the case when overwriting an existing file, since | |
1393 | the blocks are already laid out in the file system. You | |
1394 | can ignore this option unless doing huge amounts of really | |
1395 | fast IO where the red-black tree sorting CPU time becomes | |
1396 | significant. | |
3f9f4e26 | 1397 | |
f7fa2653 | 1398 | verify_offset=int Swap the verification header with data somewhere else |
546a9142 SL |
1399 | in the block before writing. Its swapped back before |
1400 | verifying. | |
1401 | ||
f7fa2653 | 1402 | verify_interval=int Write the verification header at a finer granularity |
3f9f4e26 SL |
1403 | than the blocksize. It will be written for chunks the |
1404 | size of header_interval. blocksize should divide this | |
1405 | evenly. | |
90059d65 | 1406 | |
0e92f873 | 1407 | verify_pattern=str If set, fio will fill the io buffers with this |
e28218f3 SL |
1408 | pattern. Fio defaults to filling with totally random |
1409 | bytes, but sometimes it's interesting to fill with a known | |
1410 | pattern for io verification purposes. Depending on the | |
1411 | width of the pattern, fio will fill 1/2/3/4 bytes of the | |
0e92f873 RR |
1412 | buffer at the time(it can be either a decimal or a hex number). |
1413 | The verify_pattern if larger than a 32-bit quantity has to | |
996093bb | 1414 | be a hex number that starts with either "0x" or "0X". Use |
b638d82f | 1415 | with verify=str. Also, verify_pattern supports %o format, |
61b9861d RP |
1416 | which means that for each block offset will be written and |
1417 | then verifyied back, e.g.: | |
1418 | ||
1419 | verify_pattern=%o | |
1420 | ||
1421 | Or use combination of everything: | |
1422 | verify_pattern=0xff%o"abcd"-12 | |
e28218f3 | 1423 | |
68e1f29a | 1424 | verify_fatal=bool Normally fio will keep checking the entire contents |
a12a3b4d JA |
1425 | before quitting on a block verification failure. If this |
1426 | option is set, fio will exit the job on the first observed | |
1427 | failure. | |
e8462bd8 | 1428 | |
b463e936 JA |
1429 | verify_dump=bool If set, dump the contents of both the original data |
1430 | block and the data block we read off disk to files. This | |
1431 | allows later analysis to inspect just what kind of data | |
ef71e317 | 1432 | corruption occurred. Off by default. |
b463e936 | 1433 | |
e8462bd8 JA |
1434 | verify_async=int Fio will normally verify IO inline from the submitting |
1435 | thread. This option takes an integer describing how many | |
1436 | async offload threads to create for IO verification instead, | |
1437 | causing fio to offload the duty of verifying IO contents | |
c85c324c JA |
1438 | to one or more separate threads. If using this offload |
1439 | option, even sync IO engines can benefit from using an | |
1440 | iodepth setting higher than 1, as it allows them to have | |
1441 | IO in flight while verifies are running. | |
e8462bd8 JA |
1442 | |
1443 | verify_async_cpus=str Tell fio to set the given CPU affinity on the | |
1444 | async IO verification threads. See cpus_allowed for the | |
1445 | format used. | |
6f87418f JA |
1446 | |
1447 | verify_backlog=int Fio will normally verify the written contents of a | |
1448 | job that utilizes verify once that job has completed. In | |
1449 | other words, everything is written then everything is read | |
1450 | back and verified. You may want to verify continually | |
1451 | instead for a variety of reasons. Fio stores the meta data | |
1452 | associated with an IO block in memory, so for large | |
1453 | verify workloads, quite a bit of memory would be used up | |
1454 | holding this meta data. If this option is enabled, fio | |
f42195a3 JA |
1455 | will write only N blocks before verifying these blocks. |
1456 | ||
6f87418f JA |
1457 | verify_backlog_batch=int Control how many blocks fio will verify |
1458 | if verify_backlog is set. If not set, will default to | |
1459 | the value of verify_backlog (meaning the entire queue | |
f42195a3 JA |
1460 | is read back and verified). If verify_backlog_batch is |
1461 | less than verify_backlog then not all blocks will be verified, | |
1462 | if verify_backlog_batch is larger than verify_backlog, some | |
1463 | blocks will be verified more than once. | |
66c098b8 | 1464 | |
ca09be4b JA |
1465 | verify_state_save=bool When a job exits during the write phase of a verify |
1466 | workload, save its current state. This allows fio to replay | |
1467 | up until that point, if the verify state is loaded for the | |
1468 | verify read phase. The format of the filename is, roughly, | |
1469 | <type>-<jobname>-<jobindex>-verify.state. <type> is "local" | |
1470 | for a local run, "sock" for a client/server socket connection, | |
1471 | and "ip" (192.168.0.1, for instance) for a networked | |
1472 | client/server connection. | |
1473 | ||
1474 | verify_state_load=bool If a verify termination trigger was used, fio stores | |
1475 | the current write state of each thread. This can be used at | |
1476 | verification time so that fio knows how far it should verify. | |
1477 | Without this information, fio will run a full verification | |
1478 | pass, according to the settings in the job file used. | |
1479 | ||
d392365e | 1480 | stonewall |
de8f6de9 | 1481 | wait_for_previous Wait for preceding jobs in the job file to exit, before |
71bfa161 | 1482 | starting this one. Can be used to insert serialization |
b3d62a75 JA |
1483 | points in the job file. A stone wall also implies starting |
1484 | a new reporting group. | |
1485 | ||
abcab6af | 1486 | new_group Start a new reporting group. See: group_reporting. |
71bfa161 JA |
1487 | |
1488 | numjobs=int Create the specified number of clones of this job. May be | |
1489 | used to setup a larger number of threads/processes doing | |
abcab6af AV |
1490 | the same thing. Each thread is reported separately; to see |
1491 | statistics for all clones as a whole, use group_reporting in | |
1492 | conjunction with new_group. | |
1493 | ||
1494 | group_reporting It may sometimes be interesting to display statistics for | |
04b2f799 JA |
1495 | groups of jobs as a whole instead of for each individual job. |
1496 | This is especially true if 'numjobs' is used; looking at | |
1497 | individual thread/process output quickly becomes unwieldy. | |
1498 | To see the final report per-group instead of per-job, use | |
1499 | 'group_reporting'. Jobs in a file will be part of the same | |
1500 | reporting group, unless if separated by a stonewall, or by | |
1501 | using 'new_group'. | |
71bfa161 JA |
1502 | |
1503 | thread fio defaults to forking jobs, however if this option is | |
1504 | given, fio will use pthread_create(3) to create threads | |
1505 | instead. | |
1506 | ||
f7fa2653 | 1507 | zonesize=int Divide a file into zones of the specified size. See zoneskip. |
71bfa161 | 1508 | |
f7fa2653 | 1509 | zoneskip=int Skip the specified number of bytes when zonesize data has |
71bfa161 JA |
1510 | been read. The two zone options can be used to only do |
1511 | io on zones of a file. | |
1512 | ||
076efc7c | 1513 | write_iolog=str Write the issued io patterns to the specified file. See |
5b42a488 SH |
1514 | read_iolog. Specify a separate file for each job, otherwise |
1515 | the iologs will be interspersed and the file may be corrupt. | |
71bfa161 | 1516 | |
076efc7c | 1517 | read_iolog=str Open an iolog with the specified file name and replay the |
71bfa161 | 1518 | io patterns it contains. This can be used to store a |
6df8adaa JA |
1519 | workload and replay it sometime later. The iolog given |
1520 | may also be a blktrace binary file, which allows fio | |
1521 | to replay a workload captured by blktrace. See blktrace | |
1522 | for how to capture such logging data. For blktrace replay, | |
1523 | the file needs to be turned into a blkparse binary data | |
ea3e51c3 | 1524 | file first (blkparse <device> -o /dev/null -d file_for_fio.bin). |
66c098b8 | 1525 | |
64bbb865 | 1526 | replay_no_stall=int When replaying I/O with read_iolog the default behavior |
62776229 JA |
1527 | is to attempt to respect the time stamps within the log and |
1528 | replay them with the appropriate delay between IOPS. By | |
1529 | setting this variable fio will not respect the timestamps and | |
1530 | attempt to replay them as fast as possible while still | |
1531 | respecting ordering. The result is the same I/O pattern to a | |
1532 | given device, but different timings. | |
71bfa161 | 1533 | |
d1c46c04 DN |
1534 | replay_redirect=str While replaying I/O patterns using read_iolog the |
1535 | default behavior is to replay the IOPS onto the major/minor | |
1536 | device that each IOP was recorded from. This is sometimes | |
de8f6de9 | 1537 | undesirable because on a different machine those major/minor |
d1c46c04 DN |
1538 | numbers can map to a different device. Changing hardware on |
1539 | the same system can also result in a different major/minor | |
1540 | mapping. Replay_redirect causes all IOPS to be replayed onto | |
1541 | the single specified device regardless of the device it was | |
1542 | recorded from. i.e. replay_redirect=/dev/sdc would cause all | |
1543 | IO in the blktrace to be replayed onto /dev/sdc. This means | |
1544 | multiple devices will be replayed onto a single, if the trace | |
1545 | contains multiple devices. If you want multiple devices to be | |
1546 | replayed concurrently to multiple redirected devices you must | |
1547 | blkparse your trace into separate traces and replay them with | |
1548 | independent fio invocations. Unfortuantely this also breaks | |
1549 | the strict time ordering between multiple device accesses. | |
1550 | ||
0c63576e JA |
1551 | replay_align=int Force alignment of IO offsets and lengths in a trace |
1552 | to this power of 2 value. | |
1553 | ||
1554 | replay_scale=int Scale sector offsets down by this factor when | |
1555 | replaying traces. | |
1556 | ||
3a5db920 JA |
1557 | per_job_logs=bool If set, this generates bw/clat/iops log with per |
1558 | file private filenames. If not set, jobs with identical names | |
1559 | will share the log filename. Default: true. | |
1560 | ||
e3cedca7 | 1561 | write_bw_log=str If given, write a bandwidth log of the jobs in this job |
71bfa161 | 1562 | file. Can be used to store data of the bandwidth of the |
e0da9bc2 JA |
1563 | jobs in their lifetime. The included fio_generate_plots |
1564 | script uses gnuplot to turn these text files into nice | |
ddb754db | 1565 | graphs. See write_lat_log for behaviour of given |
8ad3b3dd JA |
1566 | filename. For this option, the suffix is _bw.x.log, where |
1567 | x is the index of the job (1..N, where N is the number of | |
3a5db920 | 1568 | jobs). If 'per_job_logs' is false, then the filename will not |
a3ae5b05 | 1569 | include the job index. See 'Log File Formats'. |
71bfa161 | 1570 | |
e3cedca7 | 1571 | write_lat_log=str Same as write_bw_log, except that this option stores io |
02af0988 JA |
1572 | submission, completion, and total latencies instead. If no |
1573 | filename is given with this option, the default filename of | |
1574 | "jobname_type.log" is used. Even if the filename is given, | |
1575 | fio will still append the type of log. So if one specifies | |
e3cedca7 JA |
1576 | |
1577 | write_lat_log=foo | |
1578 | ||
8ad3b3dd JA |
1579 | The actual log names will be foo_slat.x.log, foo_clat.x.log, |
1580 | and foo_lat.x.log, where x is the index of the job (1..N, | |
1581 | where N is the number of jobs). This helps fio_generate_plot | |
3a5db920 | 1582 | fine the logs automatically. If 'per_job_logs' is false, then |
a3ae5b05 JA |
1583 | the filename will not include the job index. See 'Log File |
1584 | Formats'. | |
71bfa161 | 1585 | |
b8bc8cba JA |
1586 | write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is |
1587 | given with this option, the default filename of | |
8ad3b3dd JA |
1588 | "jobname_type.x.log" is used,where x is the index of the job |
1589 | (1..N, where N is the number of jobs). Even if the filename | |
3a5db920 JA |
1590 | is given, fio will still append the type of log. If |
1591 | 'per_job_logs' is false, then the filename will not include | |
a3ae5b05 | 1592 | the job index. See 'Log File Formats'. |
b8bc8cba JA |
1593 | |
1594 | log_avg_msec=int By default, fio will log an entry in the iops, latency, | |
1595 | or bw log for every IO that completes. When writing to the | |
1596 | disk log, that can quickly grow to a very large size. Setting | |
1597 | this option makes fio average the each log entry over the | |
1598 | specified period of time, reducing the resolution of the log. | |
4b1ddb7a JA |
1599 | See log_max_value as well. Defaults to 0, logging all entries. |
1600 | ||
1601 | log_max_value=bool If log_avg_msec is set, fio logs the average over that | |
1602 | window. If you instead want to log the maximum value, set this | |
1603 | option to 1. Defaults to 0, meaning that averaged values are | |
1604 | logged. | |
b8bc8cba | 1605 | |
ae588852 JA |
1606 | log_offset=int If this is set, the iolog options will include the byte |
1607 | offset for the IO entry as well as the other data values. | |
1608 | ||
aee2ab67 JA |
1609 | log_compression=int If this is set, fio will compress the IO logs as |
1610 | it goes, to keep the memory footprint lower. When a log | |
1611 | reaches the specified size, that chunk is removed and | |
1612 | compressed in the background. Given that IO logs are | |
1613 | fairly highly compressible, this yields a nice memory | |
1614 | savings for longer runs. The downside is that the | |
1615 | compression will consume some background CPU cycles, so | |
1616 | it may impact the run. This, however, is also true if | |
1617 | the logging ends up consuming most of the system memory. | |
1618 | So pick your poison. The IO logs are saved normally at the | |
1619 | end of a run, by decompressing the chunks and storing them | |
1620 | in the specified log file. This feature depends on the | |
1621 | availability of zlib. | |
1622 | ||
c08f9fe2 JA |
1623 | log_compression_cpus=str Define the set of CPUs that are allowed to |
1624 | handle online log compression for the IO jobs. This can | |
1625 | provide better isolation between performance sensitive jobs, | |
1626 | and background compression work. | |
1627 | ||
1628 | log_store_compressed=bool If set, fio will store the log files in a | |
1629 | compressed format. They can be decompressed with fio, using | |
1630 | the --inflate-log command line parameter. The files will be | |
1631 | stored with a .fz suffix. | |
b26317c9 | 1632 | |
66347cfa DE |
1633 | block_error_percentiles=bool If set, record errors in trim block-sized |
1634 | units from writes and trims and output a histogram of | |
1635 | how many trims it took to get to errors, and what kind | |
1636 | of error was encountered. | |
1637 | ||
f7fa2653 | 1638 | lockmem=int Pin down the specified amount of memory with mlock(2). Can |
71bfa161 JA |
1639 | potentially be used instead of removing memory or booting |
1640 | with less memory to simulate a smaller amount of memory. | |
81c6b6cd | 1641 | The amount specified is per worker. |
71bfa161 JA |
1642 | |
1643 | exec_prerun=str Before running this job, issue the command specified | |
74c8c488 JA |
1644 | through system(3). Output is redirected in a file called |
1645 | jobname.prerun.txt. | |
71bfa161 JA |
1646 | |
1647 | exec_postrun=str After the job completes, issue the command specified | |
74c8c488 JA |
1648 | though system(3). Output is redirected in a file called |
1649 | jobname.postrun.txt. | |
71bfa161 JA |
1650 | |
1651 | ioscheduler=str Attempt to switch the device hosting the file to the specified | |
1652 | io scheduler before running. | |
1653 | ||
0a839f30 JA |
1654 | disk_util=bool Generate disk utilization statistics, if the platform |
1655 | supports it. Defaults to on. | |
1656 | ||
02af0988 | 1657 | disable_lat=bool Disable measurements of total latency numbers. Useful |
9520ebb9 JA |
1658 | only for cutting back the number of calls to gettimeofday, |
1659 | as that does impact performance at really high IOPS rates. | |
1660 | Note that to really get rid of a large amount of these | |
1661 | calls, this option must be used with disable_slat and | |
1662 | disable_bw as well. | |
1663 | ||
02af0988 JA |
1664 | disable_clat=bool Disable measurements of completion latency numbers. See |
1665 | disable_lat. | |
1666 | ||
9520ebb9 | 1667 | disable_slat=bool Disable measurements of submission latency numbers. See |
02af0988 | 1668 | disable_slat. |
9520ebb9 JA |
1669 | |
1670 | disable_bw=bool Disable measurements of throughput/bandwidth numbers. See | |
02af0988 | 1671 | disable_lat. |
9520ebb9 | 1672 | |
83349190 YH |
1673 | clat_percentiles=bool Enable the reporting of percentiles of |
1674 | completion latencies. | |
1675 | ||
1676 | percentile_list=float_list Overwrite the default list of percentiles | |
66347cfa DE |
1677 | for completion latencies and the block error histogram. |
1678 | Each number is a floating number in the range (0,100], | |
1679 | and the maximum length of the list is 20. Use ':' | |
1680 | to separate the numbers, and list the numbers in ascending | |
1681 | order. For example, --percentile_list=99.5:99.9 will cause | |
1682 | fio to report the values of completion latency below which | |
1683 | 99.5% and 99.9% of the observed latencies fell, respectively. | |
83349190 | 1684 | |
23893646 JA |
1685 | clocksource=str Use the given clocksource as the base of timing. The |
1686 | supported options are: | |
1687 | ||
1688 | gettimeofday gettimeofday(2) | |
1689 | ||
1690 | clock_gettime clock_gettime(2) | |
1691 | ||
1692 | cpu Internal CPU clock source | |
1693 | ||
1694 | cpu is the preferred clocksource if it is reliable, as it | |
1695 | is very fast (and fio is heavy on time calls). Fio will | |
1696 | automatically use this clocksource if it's supported and | |
1697 | considered reliable on the system it is running on, unless | |
1698 | another clocksource is specifically set. For x86/x86-64 CPUs, | |
1699 | this means supporting TSC Invariant. | |
1700 | ||
993bf48b JA |
1701 | gtod_reduce=bool Enable all of the gettimeofday() reducing options |
1702 | (disable_clat, disable_slat, disable_bw) plus reduce | |
1703 | precision of the timeout somewhat to really shrink | |
1704 | the gettimeofday() call count. With this option enabled, | |
1705 | we only do about 0.4% of the gtod() calls we would have | |
1706 | done if all time keeping was enabled. | |
1707 | ||
be4ecfdf JA |
1708 | gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of |
1709 | execution to just getting the current time. Fio (and | |
1710 | databases, for instance) are very intensive on gettimeofday() | |
1711 | calls. With this option, you can set one CPU aside for | |
1712 | doing nothing but logging current time to a shared memory | |
1713 | location. Then the other threads/processes that run IO | |
1714 | workloads need only copy that segment, instead of entering | |
1715 | the kernel with a gettimeofday() call. The CPU set aside | |
1716 | for doing these time calls will be excluded from other | |
1717 | uses. Fio will manually clear it from the CPU mask of other | |
1718 | jobs. | |
a696fa2a | 1719 | |
06842027 | 1720 | continue_on_error=str Normally fio will exit the job on the first observed |
f2bba182 RR |
1721 | failure. If this option is set, fio will continue the job when |
1722 | there is a 'non-fatal error' (EIO or EILSEQ) until the runtime | |
1723 | is exceeded or the I/O size specified is completed. If this | |
1724 | option is used, there are two more stats that are appended, | |
1725 | the total error count and the first error. The error field | |
1726 | given in the stats is the first error that was hit during the | |
1727 | run. | |
be4ecfdf | 1728 | |
06842027 SL |
1729 | The allowed values are: |
1730 | ||
1731 | none Exit on any IO or verify errors. | |
1732 | ||
1733 | read Continue on read errors, exit on all others. | |
1734 | ||
1735 | write Continue on write errors, exit on all others. | |
1736 | ||
1737 | io Continue on any IO error, exit on all others. | |
1738 | ||
1739 | verify Continue on verify errors, exit on all others. | |
1740 | ||
1741 | all Continue on all errors. | |
1742 | ||
1743 | 0 Backward-compatible alias for 'none'. | |
1744 | ||
1745 | 1 Backward-compatible alias for 'all'. | |
1746 | ||
8b28bd41 DM |
1747 | ignore_error=str Sometimes you want to ignore some errors during test |
1748 | in that case you can specify error list for each error type. | |
1749 | ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST | |
1750 | errors for given error type is separated with ':'. Error | |
1751 | may be symbol ('ENOSPC', 'ENOMEM') or integer. | |
1752 | Example: | |
1753 | ignore_error=EAGAIN,ENOSPC:122 | |
66c098b8 BC |
1754 | This option will ignore EAGAIN from READ, and ENOSPC and |
1755 | 122(EDQUOT) from WRITE. | |
8b28bd41 DM |
1756 | |
1757 | error_dump=bool If set dump every error even if it is non fatal, true | |
1758 | by default. If disabled only fatal error will be dumped | |
66c098b8 | 1759 | |
6adb38a1 JA |
1760 | cgroup=str Add job to this control group. If it doesn't exist, it will |
1761 | be created. The system must have a mounted cgroup blkio | |
1762 | mount point for this to work. If your system doesn't have it | |
1763 | mounted, you can do so with: | |
a696fa2a JA |
1764 | |
1765 | # mount -t cgroup -o blkio none /cgroup | |
1766 | ||
a696fa2a JA |
1767 | cgroup_weight=int Set the weight of the cgroup to this value. See |
1768 | the documentation that comes with the kernel, allowed values | |
1769 | are in the range of 100..1000. | |
71bfa161 | 1770 | |
7de87099 VG |
1771 | cgroup_nodelete=bool Normally fio will delete the cgroups it has created after |
1772 | the job completion. To override this behavior and to leave | |
1773 | cgroups around after the job completion, set cgroup_nodelete=1. | |
1774 | This can be useful if one wants to inspect various cgroup | |
1775 | files after job completion. Default: false | |
1776 | ||
e0b0d892 JA |
1777 | uid=int Instead of running as the invoking user, set the user ID to |
1778 | this value before the thread/process does any work. | |
1779 | ||
1780 | gid=int Set group ID, see uid. | |
1781 | ||
9e684a49 DE |
1782 | flow_id=int The ID of the flow. If not specified, it defaults to being a |
1783 | global flow. See flow. | |
1784 | ||
1785 | flow=int Weight in token-based flow control. If this value is used, then | |
1786 | there is a 'flow counter' which is used to regulate the | |
1787 | proportion of activity between two or more jobs. fio attempts | |
1788 | to keep this flow counter near zero. The 'flow' parameter | |
1789 | stands for how much should be added or subtracted to the flow | |
1790 | counter on each iteration of the main I/O loop. That is, if | |
1791 | one job has flow=8 and another job has flow=-1, then there | |
1792 | will be a roughly 1:8 ratio in how much one runs vs the other. | |
1793 | ||
1794 | flow_watermark=int The maximum value that the absolute value of the flow | |
1795 | counter is allowed to reach before the job must wait for a | |
1796 | lower value of the counter. | |
1797 | ||
1798 | flow_sleep=int The period of time, in microseconds, to wait after the flow | |
1799 | watermark has been exceeded before retrying operations | |
1800 | ||
de890a1e SL |
1801 | In addition, there are some parameters which are only valid when a specific |
1802 | ioengine is in use. These are used identically to normal parameters, with the | |
1803 | caveat that when used on the command line, they must come after the ioengine | |
1804 | that defines them is selected. | |
1805 | ||
1806 | [libaio] userspace_reap Normally, with the libaio engine in use, fio will use | |
1807 | the io_getevents system call to reap newly returned events. | |
1808 | With this flag turned on, the AIO ring will be read directly | |
1809 | from user-space to reap events. The reaping mode is only | |
1810 | enabled when polling for a minimum of 0 events (eg when | |
1811 | iodepth_batch_complete=0). | |
1812 | ||
2cafffbe JA |
1813 | [psyncv2] hipri Set RWF_HIPRI on IO, indicating to the kernel that |
1814 | it's of higher priority than normal. | |
1815 | ||
0353050f JA |
1816 | [cpu] cpuload=int Attempt to use the specified percentage of CPU cycles. |
1817 | ||
1818 | [cpu] cpuchunks=int Split the load into cycles of the given time. In | |
1819 | microseconds. | |
1820 | ||
046395d7 JA |
1821 | [cpu] exit_on_io_done=bool Detect when IO threads are done, then exit. |
1822 | ||
de890a1e SL |
1823 | [netsplice] hostname=str |
1824 | [net] hostname=str The host name or IP address to use for TCP or UDP based IO. | |
1825 | If the job is a TCP listener or UDP reader, the hostname is not | |
b511c9aa SB |
1826 | used and must be omitted unless it is a valid UDP multicast |
1827 | address. | |
a3f001f5 | 1828 | [libhdfs] namenode=str The host name or IP address of a HDFS cluster namenode to contact. |
de890a1e SL |
1829 | |
1830 | [netsplice] port=int | |
6315af9d JA |
1831 | [net] port=int The TCP or UDP port to bind to or connect to. If this is used |
1832 | with numjobs to spawn multiple instances of the same job type, then this will | |
1833 | be the starting port number since fio will use a range of ports. | |
a3f001f5 | 1834 | [libhdfs] port=int the listening port of the HFDS cluster namenode. |
de890a1e | 1835 | |
b93b6a2e SB |
1836 | [netsplice] interface=str |
1837 | [net] interface=str The IP address of the network interface used to send or | |
1838 | receive UDP multicast | |
1839 | ||
d3a623de SB |
1840 | [netsplice] ttl=int |
1841 | [net] ttl=int Time-to-live value for outgoing UDP multicast packets. | |
1842 | Default: 1 | |
1843 | ||
1d360ffb JA |
1844 | [netsplice] nodelay=bool |
1845 | [net] nodelay=bool Set TCP_NODELAY on TCP connections. | |
1846 | ||
de890a1e SL |
1847 | [netsplice] protocol=str |
1848 | [netsplice] proto=str | |
1849 | [net] protocol=str | |
1850 | [net] proto=str The network protocol to use. Accepted values are: | |
1851 | ||
1852 | tcp Transmission control protocol | |
49ccb8c1 | 1853 | tcpv6 Transmission control protocol V6 |
f5cc3d0e | 1854 | udp User datagram protocol |
49ccb8c1 | 1855 | udpv6 User datagram protocol V6 |
de890a1e SL |
1856 | unix UNIX domain socket |
1857 | ||
1858 | When the protocol is TCP or UDP, the port must also be given, | |
1859 | as well as the hostname if the job is a TCP listener or UDP | |
1860 | reader. For unix sockets, the normal filename option should be | |
1861 | used and the port is invalid. | |
1862 | ||
1863 | [net] listen For TCP network connections, tell fio to listen for incoming | |
1864 | connections rather than initiating an outgoing connection. The | |
1865 | hostname must be omitted if this option is used. | |
1008602c | 1866 | |
b511c9aa | 1867 | [net] pingpong Normaly a network writer will just continue writing data, and |
7aeb1e94 JA |
1868 | a network reader will just consume packages. If pingpong=1 |
1869 | is set, a writer will send its normal payload to the reader, | |
1870 | then wait for the reader to send the same payload back. This | |
1871 | allows fio to measure network latencies. The submission | |
1872 | and completion latencies then measure local time spent | |
1873 | sending or receiving, and the completion latency measures | |
1874 | how long it took for the other end to receive and send back. | |
b511c9aa SB |
1875 | For UDP multicast traffic pingpong=1 should only be set for a |
1876 | single reader when multiple readers are listening to the same | |
1877 | address. | |
7aeb1e94 | 1878 | |
1008602c JA |
1879 | [net] window_size Set the desired socket buffer size for the connection. |
1880 | ||
e5f34d95 JA |
1881 | [net] mss Set the TCP maximum segment size (TCP_MAXSEG). |
1882 | ||
d54fce84 DM |
1883 | [e4defrag] donorname=str |
1884 | File will be used as a block donor(swap extents between files) | |
1885 | [e4defrag] inplace=int | |
66c098b8 | 1886 | Configure donor file blocks allocation strategy |
d54fce84 DM |
1887 | 0(default): Preallocate donor's file on init |
1888 | 1 : allocate space immidietly inside defragment event, | |
1889 | and free right after event | |
1890 | ||
65fa28ca | 1891 | [mtd] skip_bad=bool Skip operations against known bad blocks. |
de890a1e | 1892 | |
a3f001f5 FB |
1893 | [libhdfs] hdfsdirectory libhdfs will create chunk in this HDFS directory |
1894 | [libhdfs] chunck_size the size of the chunck to use for each file. | |
1895 | ||
de890a1e | 1896 | |
71bfa161 JA |
1897 | 6.0 Interpreting the output |
1898 | --------------------------- | |
1899 | ||
1900 | fio spits out a lot of output. While running, fio will display the | |
1901 | status of the jobs created. An example of that would be: | |
1902 | ||
73c8b082 | 1903 | Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s] |
71bfa161 JA |
1904 | |
1905 | The characters inside the square brackets denote the current status of | |
1906 | each thread. The possible values (in typical life cycle order) are: | |
1907 | ||
1908 | Idle Run | |
1909 | ---- --- | |
1910 | P Thread setup, but not started. | |
1911 | C Thread created. | |
9c6f6316 | 1912 | I Thread initialized, waiting or generating necessary data. |
b0f65863 | 1913 | p Thread running pre-reading file(s). |
71bfa161 JA |
1914 | R Running, doing sequential reads. |
1915 | r Running, doing random reads. | |
1916 | W Running, doing sequential writes. | |
1917 | w Running, doing random writes. | |
1918 | M Running, doing mixed sequential reads/writes. | |
1919 | m Running, doing mixed random reads/writes. | |
1920 | F Running, currently waiting for fsync() | |
3d434057 | 1921 | f Running, finishing up (writing IO logs, etc) |
fc6bd43c | 1922 | V Running, doing verification of written data. |
71bfa161 | 1923 | E Thread exited, not reaped by main thread yet. |
4f7e57a4 JA |
1924 | _ Thread reaped, or |
1925 | X Thread reaped, exited with an error. | |
a5e371a6 | 1926 | K Thread reaped, exited due to signal. |
71bfa161 | 1927 | |
3e2e48a7 JA |
1928 | Fio will condense the thread string as not to take up more space on the |
1929 | command line as is needed. For instance, if you have 10 readers and 10 | |
1930 | writers running, the output would look like this: | |
1931 | ||
1932 | Jobs: 20 (f=20): [R(10),W(10)] [4.0% done] [2103MB/0KB/0KB /s] [538K/0/0 iops] [eta 57m:36s] | |
1933 | ||
1934 | Fio will still maintain the ordering, though. So the above means that jobs | |
1935 | 1..10 are readers, and 11..20 are writers. | |
1936 | ||
71bfa161 | 1937 | The other values are fairly self explanatory - number of threads |
c9f60304 JA |
1938 | currently running and doing io, rate of io since last check (read speed |
1939 | listed first, then write speed), and the estimated completion percentage | |
1940 | and time for the running group. It's impossible to estimate runtime of | |
4f7e57a4 JA |
1941 | the following groups (if any). Note that the string is displayed in order, |
1942 | so it's possible to tell which of the jobs are currently doing what. The | |
1943 | first character is the first job defined in the job file, and so forth. | |
71bfa161 JA |
1944 | |
1945 | When fio is done (or interrupted by ctrl-c), it will show the data for | |
1946 | each thread, group of threads, and disks in that order. For each data | |
1947 | direction, the output looks like: | |
1948 | ||
1949 | Client1 (g=0): err= 0: | |
35649e58 | 1950 | write: io= 32MB, bw= 666KB/s, iops=89 , runt= 50320msec |
6104ddb6 JA |
1951 | slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92 |
1952 | clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82 | |
b22989b9 | 1953 | bw (KB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68 |
e7823a94 | 1954 | cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17 |
71619dc2 | 1955 | IO depths : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0% |
838bc709 JA |
1956 | submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% |
1957 | complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% | |
30061b97 | 1958 | issued r/w: total=0/32768, short=0/0 |
8abdce66 JA |
1959 | lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%, |
1960 | lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0% | |
71bfa161 JA |
1961 | |
1962 | The client number is printed, along with the group id and error of that | |
1963 | thread. Below is the io statistics, here for writes. In the order listed, | |
1964 | they denote: | |
1965 | ||
1966 | io= Number of megabytes io performed | |
1967 | bw= Average bandwidth rate | |
35649e58 | 1968 | iops= Average IOs performed per second |
71bfa161 | 1969 | runt= The runtime of that thread |
72fbda2a | 1970 | slat= Submission latency (avg being the average, stdev being the |
71bfa161 JA |
1971 | standard deviation). This is the time it took to submit |
1972 | the io. For sync io, the slat is really the completion | |
8a35c71e | 1973 | latency, since queue/complete is one operation there. This |
bf9a3edb | 1974 | value can be in milliseconds or microseconds, fio will choose |
8a35c71e | 1975 | the most appropriate base and print that. In the example |
0d237712 LAG |
1976 | above, milliseconds is the best scale. Note: in --minimal mode |
1977 | latencies are always expressed in microseconds. | |
71bfa161 JA |
1978 | clat= Completion latency. Same names as slat, this denotes the |
1979 | time from submission to completion of the io pieces. For | |
1980 | sync io, clat will usually be equal (or very close) to 0, | |
1981 | as the time from submit to complete is basically just | |
1982 | CPU time (io has already been done, see slat explanation). | |
1983 | bw= Bandwidth. Same names as the xlat stats, but also includes | |
1984 | an approximate percentage of total aggregate bandwidth | |
1985 | this thread received in this group. This last value is | |
1986 | only really useful if the threads in this group are on the | |
1987 | same disk, since they are then competing for disk access. | |
1988 | cpu= CPU usage. User and system time, along with the number | |
e7823a94 JA |
1989 | of context switches this thread went through, usage of |
1990 | system and user time, and finally the number of major | |
23a8e176 JA |
1991 | and minor page faults. The CPU utilization numbers are |
1992 | averages for the jobs in that reporting group, while the | |
1993 | context and fault counters are summed. | |
71619dc2 JA |
1994 | IO depths= The distribution of io depths over the job life time. The |
1995 | numbers are divided into powers of 2, so for example the | |
1996 | 16= entries includes depths up to that value but higher | |
1997 | than the previous entry. In other words, it covers the | |
1998 | range from 16 to 31. | |
838bc709 JA |
1999 | IO submit= How many pieces of IO were submitting in a single submit |
2000 | call. Each entry denotes that amount and below, until | |
2001 | the previous entry - eg, 8=100% mean that we submitted | |
2002 | anywhere in between 5-8 ios per submit call. | |
2003 | IO complete= Like the above submit number, but for completions instead. | |
30061b97 JA |
2004 | IO issued= The number of read/write requests issued, and how many |
2005 | of them were short. | |
ec118304 JA |
2006 | IO latencies= The distribution of IO completion latencies. This is the |
2007 | time from when IO leaves fio and when it gets completed. | |
2008 | The numbers follow the same pattern as the IO depths, | |
2009 | meaning that 2=1.6% means that 1.6% of the IO completed | |
8abdce66 JA |
2010 | within 2 msecs, 20=12.8% means that 12.8% of the IO |
2011 | took more than 10 msecs, but less than (or equal to) 20 msecs. | |
71bfa161 JA |
2012 | |
2013 | After each client has been listed, the group statistics are printed. They | |
2014 | will look like this: | |
2015 | ||
2016 | Run status group 0 (all jobs): | |
b22989b9 JA |
2017 | READ: io=64MB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec |
2018 | WRITE: io=64MB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec | |
71bfa161 JA |
2019 | |
2020 | For each data direction, it prints: | |
2021 | ||
2022 | io= Number of megabytes io performed. | |
2023 | aggrb= Aggregate bandwidth of threads in this group. | |
2024 | minb= The minimum average bandwidth a thread saw. | |
2025 | maxb= The maximum average bandwidth a thread saw. | |
2026 | mint= The smallest runtime of the threads in that group. | |
2027 | maxt= The longest runtime of the threads in that group. | |
2028 | ||
2029 | And finally, the disk statistics are printed. They will look like this: | |
2030 | ||
2031 | Disk stats (read/write): | |
2032 | sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% | |
2033 | ||
2034 | Each value is printed for both reads and writes, with reads first. The | |
2035 | numbers denote: | |
2036 | ||
2037 | ios= Number of ios performed by all groups. | |
2038 | merge= Number of merges io the io scheduler. | |
2039 | ticks= Number of ticks we kept the disk busy. | |
2040 | io_queue= Total time spent in the disk queue. | |
2041 | util= The disk utilization. A value of 100% means we kept the disk | |
2042 | busy constantly, 50% would be a disk idling half of the time. | |
2043 | ||
8423bd11 JA |
2044 | It is also possible to get fio to dump the current output while it is |
2045 | running, without terminating the job. To do that, send fio the USR1 signal. | |
06464907 JA |
2046 | You can also get regularly timed dumps by using the --status-interval |
2047 | parameter, or by creating a file in /tmp named fio-dump-status. If fio | |
2048 | sees this file, it will unlink it and dump the current output status. | |
8423bd11 | 2049 | |
71bfa161 JA |
2050 | |
2051 | 7.0 Terse output | |
2052 | ---------------- | |
2053 | ||
2054 | For scripted usage where you typically want to generate tables or graphs | |
6af019c9 | 2055 | of the results, fio can output the results in a semicolon separated format. |
71bfa161 JA |
2056 | The format is one long line of values, such as: |
2057 | ||
562c2d2f DN |
2058 | 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% |
2059 | A description of this job goes here. | |
2060 | ||
2061 | The job description (if provided) follows on a second line. | |
71bfa161 | 2062 | |
525c2bfa JA |
2063 | To enable terse output, use the --minimal command line option. The first |
2064 | value is the version of the terse output format. If the output has to | |
2065 | be changed for some reason, this number will be incremented by 1 to | |
2066 | signify that change. | |
6820cb3b | 2067 | |
71bfa161 JA |
2068 | Split up, the format is as follows: |
2069 | ||
5e726d0a | 2070 | terse version, fio version, jobname, groupid, error |
71bfa161 | 2071 | READ status: |
312b4af2 | 2072 | Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec) |
d86ae56c CW |
2073 | Submission latency: min, max, mean, stdev (usec) |
2074 | Completion latency: min, max, mean, stdev (usec) | |
1db92cb6 | 2075 | Completion latency percentiles: 20 fields (see below) |
d86ae56c CW |
2076 | Total latency: min, max, mean, stdev (usec) |
2077 | Bw (KB/s): min, max, aggregate percentage of total, mean, stdev | |
71bfa161 | 2078 | WRITE status: |
312b4af2 | 2079 | Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec) |
d86ae56c CW |
2080 | Submission latency: min, max, mean, stdev (usec) |
2081 | Completion latency: min, max, mean, stdev(usec) | |
1db92cb6 | 2082 | Completion latency percentiles: 20 fields (see below) |
d86ae56c CW |
2083 | Total latency: min, max, mean, stdev (usec) |
2084 | Bw (KB/s): min, max, aggregate percentage of total, mean, stdev | |
046ee302 | 2085 | CPU usage: user, system, context switches, major faults, minor faults |
2270890c | 2086 | IO depths: <=1, 2, 4, 8, 16, 32, >=64 |
562c2d2f DN |
2087 | IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000 |
2088 | IO latencies milliseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000 | |
f2f788dd JA |
2089 | Disk utilization: Disk name, Read ios, write ios, |
2090 | Read merges, write merges, | |
2091 | Read ticks, write ticks, | |
3d7cd9b4 | 2092 | Time spent in queue, disk utilization percentage |
de8f6de9 | 2093 | Additional Info (dependent on continue_on_error, default off): total # errors, first error code |
66c098b8 | 2094 | |
de8f6de9 | 2095 | Additional Info (dependent on description being set): Text description |
25c8b9d7 | 2096 | |
1db92cb6 JA |
2097 | Completion latency percentiles can be a grouping of up to 20 sets, so |
2098 | for the terse output fio writes all of them. Each field will look like this: | |
2099 | ||
2100 | 1.00%=6112 | |
2101 | ||
2102 | which is the Xth percentile, and the usec latency associated with it. | |
2103 | ||
f2f788dd JA |
2104 | For disk utilization, all disks used by fio are shown. So for each disk |
2105 | there will be a disk utilization section. | |
2106 | ||
25c8b9d7 PD |
2107 | |
2108 | 8.0 Trace file format | |
2109 | --------------------- | |
66c098b8 | 2110 | There are two trace file format that you can encounter. The older (v1) format |
25c8b9d7 PD |
2111 | is unsupported since version 1.20-rc3 (March 2008). It will still be described |
2112 | below in case that you get an old trace and want to understand it. | |
2113 | ||
2114 | In any case the trace is a simple text file with a single action per line. | |
2115 | ||
2116 | ||
2117 | 8.1 Trace file format v1 | |
2118 | ------------------------ | |
2119 | Each line represents a single io action in the following format: | |
2120 | ||
2121 | rw, offset, length | |
2122 | ||
2123 | where rw=0/1 for read/write, and the offset and length entries being in bytes. | |
2124 | ||
2125 | This format is not supported in Fio versions => 1.20-rc3. | |
2126 | ||
2127 | ||
2128 | 8.2 Trace file format v2 | |
2129 | ------------------------ | |
2130 | The second version of the trace file format was added in Fio version 1.17. | |
2131 | It allows to access more then one file per trace and has a bigger set of | |
2132 | possible file actions. | |
2133 | ||
2134 | The first line of the trace file has to be: | |
2135 | ||
2136 | fio version 2 iolog | |
2137 | ||
2138 | Following this can be lines in two different formats, which are described below. | |
2139 | ||
2140 | The file management format: | |
2141 | ||
2142 | filename action | |
2143 | ||
2144 | The filename is given as an absolute path. The action can be one of these: | |
2145 | ||
2146 | add Add the given filename to the trace | |
66c098b8 | 2147 | open Open the file with the given filename. The filename has to have |
25c8b9d7 PD |
2148 | been added with the add action before. |
2149 | close Close the file with the given filename. The file has to have been | |
2150 | opened before. | |
2151 | ||
2152 | ||
2153 | The file io action format: | |
2154 | ||
2155 | filename action offset length | |
2156 | ||
2157 | The filename is given as an absolute path, and has to have been added and opened | |
66c098b8 | 2158 | before it can be used with this format. The offset and length are given in |
25c8b9d7 PD |
2159 | bytes. The action can be one of these: |
2160 | ||
2161 | wait Wait for 'offset' microseconds. Everything below 100 is discarded. | |
5c7808fe | 2162 | The time is relative to the previous wait statement. |
25c8b9d7 PD |
2163 | read Read 'length' bytes beginning from 'offset' |
2164 | write Write 'length' bytes beginning from 'offset' | |
2165 | sync fsync() the file | |
2166 | datasync fdatasync() the file | |
2167 | trim trim the given file from the given 'offset' for 'length' bytes | |
f2a2ce0e HL |
2168 | |
2169 | ||
2170 | 9.0 CPU idleness profiling | |
06464907 | 2171 | -------------------------- |
f2a2ce0e HL |
2172 | In some cases, we want to understand CPU overhead in a test. For example, |
2173 | we test patches for the specific goodness of whether they reduce CPU usage. | |
2174 | fio implements a balloon approach to create a thread per CPU that runs at | |
2175 | idle priority, meaning that it only runs when nobody else needs the cpu. | |
2176 | By measuring the amount of work completed by the thread, idleness of each | |
2177 | CPU can be derived accordingly. | |
2178 | ||
2179 | An unit work is defined as touching a full page of unsigned characters. Mean | |
2180 | and standard deviation of time to complete an unit work is reported in "unit | |
2181 | work" section. Options can be chosen to report detailed percpu idleness or | |
2182 | overall system idleness by aggregating percpu stats. | |
99b9a85a JA |
2183 | |
2184 | ||
2185 | 10.0 Verification and triggers | |
2186 | ------------------------------ | |
2187 | Fio is usually run in one of two ways, when data verification is done. The | |
2188 | first is a normal write job of some sort with verify enabled. When the | |
2189 | write phase has completed, fio switches to reads and verifies everything | |
2190 | it wrote. The second model is running just the write phase, and then later | |
2191 | on running the same job (but with reads instead of writes) to repeat the | |
2192 | same IO patterns and verify the contents. Both of these methods depend | |
2193 | on the write phase being completed, as fio otherwise has no idea how much | |
2194 | data was written. | |
2195 | ||
2196 | With verification triggers, fio supports dumping the current write state | |
2197 | to local files. Then a subsequent read verify workload can load this state | |
2198 | and know exactly where to stop. This is useful for testing cases where | |
2199 | power is cut to a server in a managed fashion, for instance. | |
2200 | ||
2201 | A verification trigger consists of two things: | |
2202 | ||
2203 | 1) Storing the write state of each job | |
2204 | 2) Executing a trigger command | |
2205 | ||
2206 | The write state is relatively small, on the order of hundreds of bytes | |
2207 | to single kilobytes. It contains information on the number of completions | |
2208 | done, the last X completions, etc. | |
2209 | ||
2210 | A trigger is invoked either through creation ('touch') of a specified | |
2211 | file in the system, or through a timeout setting. If fio is run with | |
2212 | --trigger-file=/tmp/trigger-file, then it will continually check for | |
2213 | the existence of /tmp/trigger-file. When it sees this file, it will | |
2214 | fire off the trigger (thus saving state, and executing the trigger | |
2215 | command). | |
2216 | ||
2217 | For client/server runs, there's both a local and remote trigger. If | |
2218 | fio is running as a server backend, it will send the job states back | |
2219 | to the client for safe storage, then execute the remote trigger, if | |
2220 | specified. If a local trigger is specified, the server will still send | |
2221 | back the write state, but the client will then execute the trigger. | |
2222 | ||
2223 | 10.1 Verification trigger example | |
2224 | --------------------------------- | |
2225 | Lets say we want to run a powercut test on the remote machine 'server'. | |
2226 | Our write workload is in write-test.fio. We want to cut power to 'server' | |
2227 | at some point during the run, and we'll run this test from the safety | |
2228 | or our local machine, 'localbox'. On the server, we'll start the fio | |
2229 | backend normally: | |
2230 | ||
2231 | server# fio --server | |
2232 | ||
2233 | and on the client, we'll fire off the workload: | |
2234 | ||
2235 | localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\"" | |
2236 | ||
2237 | We set /tmp/my-trigger as the trigger file, and we tell fio to execute | |
2238 | ||
2239 | echo b > /proc/sysrq-trigger | |
2240 | ||
2241 | on the server once it has received the trigger and sent us the write | |
2242 | state. This will work, but it's not _really_ cutting power to the server, | |
2243 | it's merely abruptly rebooting it. If we have a remote way of cutting | |
2244 | power to the server through IPMI or similar, we could do that through | |
2245 | a local trigger command instead. Lets assume we have a script that does | |
2246 | IPMI reboot of a given hostname, ipmi-reboot. On localbox, we could | |
2247 | then have run fio with a local trigger instead: | |
2248 | ||
2249 | localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server" | |
2250 | ||
2251 | For this case, fio would wait for the server to send us the write state, | |
2252 | then execute 'ipmi-reboot server' when that happened. | |
2253 | ||
29dbd1e5 | 2254 | 10.2 Loading verify state |
99b9a85a JA |
2255 | ------------------------- |
2256 | To load store write state, read verification job file must contain | |
2257 | the verify_state_load option. If that is set, fio will load the previously | |
2258 | stored state. For a local fio run this is done by loading the files directly, | |
2259 | and on a client/server run, the server backend will ask the client to send | |
2260 | the files over and load them from there. | |
a3ae5b05 JA |
2261 | |
2262 | ||
2263 | 11.0 Log File Formats | |
2264 | --------------------- | |
2265 | ||
2266 | Fio supports a variety of log file formats, for logging latencies, bandwidth, | |
2267 | and IOPS. The logs share a common format, which looks like this: | |
2268 | ||
2269 | time (msec), value, data direction, offset | |
2270 | ||
2271 | Time for the log entry is always in milliseconds. The value logged depends | |
2272 | on the type of log, it will be one of the following: | |
2273 | ||
2274 | Latency log Value is latency in usecs | |
2275 | Bandwidth log Value is in KB/sec | |
2276 | IOPS log Value is IOPS | |
2277 | ||
2278 | Data direction is one of the following: | |
2279 | ||
2280 | 0 IO is a READ | |
2281 | 1 IO is a WRITE | |
2282 | 2 IO is a TRIM | |
2283 | ||
2284 | The offset is the offset, in bytes, from the start of the file, for that | |
2285 | particular IO. The logging of the offset can be toggled with 'log_offset'. | |
2286 | ||
2287 | If windowed logging is enabled though 'log_avg_msec', then fio doesn't log | |
2288 | individual IOs. Instead of logs the average values over the specified | |
2289 | period of time. Since 'data direction' and 'offset' are per-IO values, | |
2290 | they aren't applicable if windowed logging is enabled. If windowed logging | |
2291 | is enabled and 'log_max_value' is set, then fio logs maximum values in | |
2292 | that window instead of averages. | |
2293 |