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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 | |
11 | ||
12 | ||
13 | 1.0 Overview and history | |
14 | ------------------------ | |
15 | fio was originally written to save me the hassle of writing special test | |
16 | case programs when I wanted to test a specific workload, either for | |
17 | performance reasons or to find/reproduce a bug. The process of writing | |
18 | such a test app can be tiresome, especially if you have to do it often. | |
19 | Hence I needed a tool that would be able to simulate a given io workload | |
20 | without resorting to writing a tailored test case again and again. | |
21 | ||
22 | A test work load is difficult to define, though. There can be any number | |
23 | of processes or threads involved, and they can each be using their own | |
24 | way of generating io. You could have someone dirtying large amounts of | |
25 | memory in an memory mapped file, or maybe several threads issuing | |
26 | reads using asynchronous io. fio needed to be flexible enough to | |
27 | simulate both of these cases, and many more. | |
28 | ||
29 | 2.0 How fio works | |
30 | ----------------- | |
31 | The first step in getting fio to simulate a desired io workload, is | |
32 | writing a job file describing that specific setup. A job file may contain | |
33 | any number of threads and/or files - the typical contents of the job file | |
34 | is a global section defining shared parameters, and one or more job | |
35 | sections describing the jobs involved. When run, fio parses this file | |
36 | and sets everything up as described. If we break down a job from top to | |
37 | bottom, it contains the following basic parameters: | |
38 | ||
39 | IO type Defines the io pattern issued to the file(s). | |
40 | We may only be reading sequentially from this | |
41 | file(s), or we may be writing randomly. Or even | |
42 | mixing reads and writes, sequentially or randomly. | |
43 | ||
44 | Block size In how large chunks are we issuing io? This may be | |
45 | a single value, or it may describe a range of | |
46 | block sizes. | |
47 | ||
48 | IO size How much data are we going to be reading/writing. | |
49 | ||
50 | IO engine How do we issue io? We could be memory mapping the | |
51 | file, we could be using regular read/write, we | |
d0ff85df | 52 | could be using splice, async io, syslet, or even |
71bfa161 JA |
53 | SG (SCSI generic sg). |
54 | ||
6c219763 | 55 | IO depth If the io engine is async, how large a queuing |
71bfa161 JA |
56 | depth do we want to maintain? |
57 | ||
58 | IO type Should we be doing buffered io, or direct/raw io? | |
59 | ||
60 | Num files How many files are we spreading the workload over. | |
61 | ||
62 | Num threads How many threads or processes should we spread | |
63 | this workload over. | |
64 | ||
65 | The above are the basic parameters defined for a workload, in addition | |
66 | there's a multitude of parameters that modify other aspects of how this | |
67 | job behaves. | |
68 | ||
69 | ||
70 | 3.0 Running fio | |
71 | --------------- | |
72 | See the README file for command line parameters, there are only a few | |
73 | of them. | |
74 | ||
75 | Running fio is normally the easiest part - you just give it the job file | |
76 | (or job files) as parameters: | |
77 | ||
78 | $ fio job_file | |
79 | ||
80 | and it will start doing what the job_file tells it to do. You can give | |
81 | more than one job file on the command line, fio will serialize the running | |
82 | of those files. Internally that is the same as using the 'stonewall' | |
83 | parameter described the the parameter section. | |
84 | ||
b4692828 JA |
85 | If the job file contains only one job, you may as well just give the |
86 | parameters on the command line. The command line parameters are identical | |
87 | to the job parameters, with a few extra that control global parameters | |
88 | (see README). For example, for the job file parameter iodepth=2, the | |
c2b1e753 JA |
89 | mirror command line option would be --iodepth 2 or --iodepth=2. You can |
90 | also use the command line for giving more than one job entry. For each | |
91 | --name option that fio sees, it will start a new job with that name. | |
92 | Command line entries following a --name entry will apply to that job, | |
93 | until there are no more entries or a new --name entry is seen. This is | |
94 | similar to the job file options, where each option applies to the current | |
95 | job until a new [] job entry is seen. | |
b4692828 | 96 | |
71bfa161 JA |
97 | fio does not need to run as root, except if the files or devices specified |
98 | in the job section requires that. Some other options may also be restricted, | |
6c219763 | 99 | such as memory locking, io scheduler switching, and decreasing the nice value. |
71bfa161 JA |
100 | |
101 | ||
102 | 4.0 Job file format | |
103 | ------------------- | |
104 | As previously described, fio accepts one or more job files describing | |
105 | what it is supposed to do. The job file format is the classic ini file, | |
106 | where the names enclosed in [] brackets define the job name. You are free | |
107 | to use any ascii name you want, except 'global' which has special meaning. | |
108 | A global section sets defaults for the jobs described in that file. A job | |
109 | may override a global section parameter, and a job file may even have | |
110 | several global sections if so desired. A job is only affected by a global | |
65db0851 JA |
111 | section residing above it. If the first character in a line is a ';' or a |
112 | '#', the entire line is discarded as a comment. | |
71bfa161 | 113 | |
3c54bc46 | 114 | So let's look at a really simple job file that defines two processes, each |
71bfa161 JA |
115 | randomly reading from a 128MiB file. |
116 | ||
117 | ; -- start job file -- | |
118 | [global] | |
119 | rw=randread | |
120 | size=128m | |
121 | ||
122 | [job1] | |
123 | ||
124 | [job2] | |
125 | ||
126 | ; -- end job file -- | |
127 | ||
128 | As you can see, the job file sections themselves are empty as all the | |
129 | described parameters are shared. As no filename= option is given, fio | |
c2b1e753 JA |
130 | makes up a filename for each of the jobs as it sees fit. On the command |
131 | line, this job would look as follows: | |
132 | ||
133 | $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2 | |
134 | ||
71bfa161 | 135 | |
3c54bc46 | 136 | Let's look at an example that has a number of processes writing randomly |
71bfa161 JA |
137 | to files. |
138 | ||
139 | ; -- start job file -- | |
140 | [random-writers] | |
141 | ioengine=libaio | |
142 | iodepth=4 | |
143 | rw=randwrite | |
144 | bs=32k | |
145 | direct=0 | |
146 | size=64m | |
147 | numjobs=4 | |
148 | ||
149 | ; -- end job file -- | |
150 | ||
151 | Here we have no global section, as we only have one job defined anyway. | |
152 | We want to use async io here, with a depth of 4 for each file. We also | |
153 | increased the buffer size used to 32KiB and define numjobs to 4 to | |
154 | fork 4 identical jobs. The result is 4 processes each randomly writing | |
b4692828 JA |
155 | to their own 64MiB file. Instead of using the above job file, you could |
156 | have given the parameters on the command line. For this case, you would | |
157 | specify: | |
158 | ||
159 | $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4 | |
71bfa161 | 160 | |
3c54bc46 AC |
161 | fio also supports environment variable expansion in job files. Any |
162 | substring of the form "${VARNAME}" as part of an option value (in other | |
163 | words, on the right of the `='), will be expanded to the value of the | |
164 | environment variable called VARNAME. If no such environment variable | |
165 | is defined, or VARNAME is the empty string, the empty string will be | |
166 | substituted. | |
167 | ||
168 | As an example, let's look at a sample fio invocation and job file: | |
169 | ||
170 | $ SIZE=64m NUMJOBS=4 fio jobfile.fio | |
171 | ||
172 | ; -- start job file -- | |
173 | [random-writers] | |
174 | rw=randwrite | |
175 | size=${SIZE} | |
176 | numjobs=${NUMJOBS} | |
177 | ; -- end job file -- | |
178 | ||
179 | This will expand to the following equivalent job file at runtime: | |
180 | ||
181 | ; -- start job file -- | |
182 | [random-writers] | |
183 | rw=randwrite | |
184 | size=64m | |
185 | numjobs=4 | |
186 | ; -- end job file -- | |
187 | ||
71bfa161 JA |
188 | fio ships with a few example job files, you can also look there for |
189 | inspiration. | |
190 | ||
191 | ||
192 | 5.0 Detailed list of parameters | |
193 | ------------------------------- | |
194 | ||
195 | This section describes in details each parameter associated with a job. | |
196 | Some parameters take an option of a given type, such as an integer or | |
197 | a string. The following types are used: | |
198 | ||
199 | str String. This is a sequence of alpha characters. | |
e417fd66 JA |
200 | time Integer with possible time postfix. In seconds unless otherwise |
201 | specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds, | |
202 | minutes, and hours. | |
f7fa2653 | 203 | int SI integer. A whole number value, which may contain a postfix |
71bfa161 | 204 | describing the base of the number. Accepted postfixes are k/m/g, |
6c219763 | 205 | meaning kilo, mega, and giga. So if you want to specify 4096, |
71bfa161 JA |
206 | you could either write out '4096' or just give 4k. The postfixes |
207 | signify base 2 values, so 1024 is 1k and 1024k is 1m and so on. | |
43159d18 | 208 | If the option accepts an upper and lower range, use a colon ':' |
ef67a8a3 JA |
209 | or minus '-' to separate such values. May also include a prefix |
210 | to indicate numbers base. If 0x is used, the number is assumed to | |
211 | be hexadecimal. See irange. | |
71bfa161 JA |
212 | bool Boolean. Usually parsed as an integer, however only defined for |
213 | true and false (1 and 0). | |
214 | irange Integer range with postfix. Allows value range to be given, such | |
bf9a3edb | 215 | as 1024-4096. A colon may also be used as the separator, eg |
0c9baf91 JA |
216 | 1k:4k. If the option allows two sets of ranges, they can be |
217 | specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see | |
f7fa2653 | 218 | int. |
71bfa161 JA |
219 | |
220 | With the above in mind, here follows the complete list of fio job | |
221 | parameters. | |
222 | ||
223 | name=str ASCII name of the job. This may be used to override the | |
224 | name printed by fio for this job. Otherwise the job | |
c2b1e753 | 225 | name is used. On the command line this parameter has the |
6c219763 | 226 | special purpose of also signaling the start of a new |
c2b1e753 | 227 | job. |
71bfa161 | 228 | |
61697c37 JA |
229 | description=str Text description of the job. Doesn't do anything except |
230 | dump this text description when this job is run. It's | |
231 | not parsed. | |
232 | ||
71bfa161 JA |
233 | directory=str Prefix filenames with this directory. Used to places files |
234 | in a different location than "./". | |
235 | ||
236 | filename=str Fio normally makes up a filename based on the job name, | |
237 | thread number, and file number. If you want to share | |
238 | files between threads in a job or several jobs, specify | |
ed92ac0c | 239 | a filename for each of them to override the default. If |
414c2a3e JA |
240 | the ioengine used is 'net', the filename is the host, port, |
241 | and protocol to use in the format of =host/port/protocol. | |
242 | See ioengine=net for more. If the ioengine is file based, you | |
243 | can specify a number of files by separating the names with a | |
244 | ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb | |
245 | as the two working files, you would use | |
246 | filename=/dev/sda:/dev/sdb. '-' is a reserved name, meaning | |
247 | stdin or stdout. Which of the two depends on the read/write | |
248 | direction set. | |
71bfa161 | 249 | |
bbf6b540 JA |
250 | opendir=str Tell fio to recursively add any file it can find in this |
251 | directory and down the file system tree. | |
252 | ||
4d4e80f2 JA |
253 | lockfile=str Fio defaults to not doing any locking files before it does |
254 | IO to them. If a file or file descriptor is shared, fio | |
255 | can serialize IO to that file to make the end result | |
256 | consistent. This is usual for emulating real workloads that | |
257 | share files. The lock modes are: | |
258 | ||
259 | none No locking. The default. | |
260 | exclusive Only one thread/process may do IO, | |
261 | excluding all others. | |
262 | readwrite Read-write locking on the file. Many | |
263 | readers may access the file at the | |
264 | same time, but writes get exclusive | |
265 | access. | |
266 | ||
267 | The option may be post-fixed with a lock batch number. If | |
268 | set, then each thread/process may do that amount of IOs to | |
bf9a3edb | 269 | the file before giving up the lock. Since lock acquisition is |
4d4e80f2 | 270 | expensive, batching the lock/unlocks will speed up IO. |
29c1349f | 271 | |
d3aad8f2 | 272 | readwrite=str |
71bfa161 JA |
273 | rw=str Type of io pattern. Accepted values are: |
274 | ||
275 | read Sequential reads | |
276 | write Sequential writes | |
277 | randwrite Random writes | |
278 | randread Random reads | |
279 | rw Sequential mixed reads and writes | |
280 | randrw Random mixed reads and writes | |
281 | ||
282 | For the mixed io types, the default is to split them 50/50. | |
283 | For certain types of io the result may still be skewed a bit, | |
211097b2 JA |
284 | since the speed may be different. It is possible to specify |
285 | a number of IO's to do before getting a new offset - this | |
286 | is only useful for random IO, where fio would normally | |
287 | generate a new random offset for every IO. If you append | |
288 | eg 8 to randread, you would get a new random offset for | |
289 | every 8 IO's. The result would be a seek for only every 8 | |
290 | IO's, instead of for every IO. Use rw=randread:8 to specify | |
291 | that. | |
71bfa161 | 292 | |
ee738499 JA |
293 | randrepeat=bool For random IO workloads, seed the generator in a predictable |
294 | way so that results are repeatable across repetitions. | |
295 | ||
d2f3ac35 JA |
296 | fadvise_hint=bool By default, fio will use fadvise() to advise the kernel |
297 | on what IO patterns it is likely to issue. Sometimes you | |
298 | want to test specific IO patterns without telling the | |
299 | kernel about it, in which case you can disable this option. | |
300 | If set, fio will use POSIX_FADV_SEQUENTIAL for sequential | |
301 | IO and POSIX_FADV_RANDOM for random IO. | |
302 | ||
f7fa2653 | 303 | size=int The total size of file io for this job. Fio will run until |
7616cafe JA |
304 | this many bytes has been transferred, unless runtime is |
305 | limited by other options (such as 'runtime', for instance). | |
306 | Unless specific nr_files and filesize options are given, | |
307 | fio will divide this size between the available files | |
308 | specified by the job. | |
71bfa161 | 309 | |
f7fa2653 | 310 | filesize=int Individual file sizes. May be a range, in which case fio |
9c60ce64 JA |
311 | will select sizes for files at random within the given range |
312 | and limited to 'size' in total (if that is given). If not | |
313 | given, each created file is the same size. | |
314 | ||
aa31f1f1 SL |
315 | fill_device=bool Sets size to something really large and waits for ENOSPC (no |
316 | space left on device) as the terminating condition. Only makes | |
317 | sense with sequential write. | |
318 | ||
f7fa2653 JA |
319 | blocksize=int |
320 | bs=int The block size used for the io units. Defaults to 4k. Values | |
321 | can be given for both read and writes. If a single int is | |
322 | given, it will apply to both. If a second int is specified | |
f90eff5a JA |
323 | after a comma, it will apply to writes only. In other words, |
324 | the format is either bs=read_and_write or bs=read,write. | |
325 | bs=4k,8k will thus use 4k blocks for reads, and 8k blocks | |
787f7e95 JA |
326 | for writes. If you only wish to set the write size, you |
327 | can do so by passing an empty read size - bs=,8k will set | |
328 | 8k for writes and leave the read default value. | |
a00735e6 | 329 | |
2b7a01d0 JA |
330 | blockalign=int |
331 | ba=int At what boundary to align random IO offsets. Defaults to | |
332 | the same as 'blocksize' the minimum blocksize given. | |
333 | Minimum alignment is typically 512b for using direct IO, | |
334 | though it usually depends on the hardware block size. This | |
335 | option is mutually exclusive with using a random map for | |
336 | files, so it will turn off that option. | |
337 | ||
d3aad8f2 | 338 | blocksize_range=irange |
71bfa161 JA |
339 | bsrange=irange Instead of giving a single block size, specify a range |
340 | and fio will mix the issued io block sizes. The issued | |
341 | io unit will always be a multiple of the minimum value | |
f90eff5a JA |
342 | given (also see bs_unaligned). Applies to both reads and |
343 | writes, however a second range can be given after a comma. | |
344 | See bs=. | |
a00735e6 | 345 | |
564ca972 JA |
346 | bssplit=str Sometimes you want even finer grained control of the |
347 | block sizes issued, not just an even split between them. | |
348 | This option allows you to weight various block sizes, | |
349 | so that you are able to define a specific amount of | |
350 | block sizes issued. The format for this option is: | |
351 | ||
352 | bssplit=blocksize/percentage:blocksize/percentage | |
353 | ||
354 | for as many block sizes as needed. So if you want to define | |
355 | a workload that has 50% 64k blocks, 10% 4k blocks, and | |
356 | 40% 32k blocks, you would write: | |
357 | ||
358 | bssplit=4k/10:64k/50:32k/40 | |
359 | ||
360 | Ordering does not matter. If the percentage is left blank, | |
361 | fio will fill in the remaining values evenly. So a bssplit | |
362 | option like this one: | |
363 | ||
364 | bssplit=4k/50:1k/:32k/ | |
365 | ||
366 | would have 50% 4k ios, and 25% 1k and 32k ios. The percentages | |
367 | always add up to 100, if bssplit is given a range that adds | |
368 | up to more, it will error out. | |
369 | ||
720e84ad JA |
370 | bssplit also supports giving separate splits to reads and |
371 | writes. The format is identical to what bs= accepts. You | |
372 | have to separate the read and write parts with a comma. So | |
373 | if you want a workload that has 50% 2k reads and 50% 4k reads, | |
374 | while having 90% 4k writes and 10% 8k writes, you would | |
375 | specify: | |
376 | ||
377 | bssplit=2k/50:4k/50,4k/90,8k/10 | |
378 | ||
d3aad8f2 | 379 | blocksize_unaligned |
690adba3 JA |
380 | bs_unaligned If this option is given, any byte size value within bsrange |
381 | may be used as a block range. This typically wont work with | |
382 | direct IO, as that normally requires sector alignment. | |
71bfa161 | 383 | |
e9459e5a JA |
384 | zero_buffers If this option is given, fio will init the IO buffers to |
385 | all zeroes. The default is to fill them with random data. | |
386 | ||
5973cafb JA |
387 | refill_buffers If this option is given, fio will refill the IO buffers |
388 | on every submit. The default is to only fill it at init | |
389 | time and reuse that data. Only makes sense if zero_buffers | |
41ccd845 JA |
390 | isn't specified, naturally. If data verification is enabled, |
391 | refill_buffers is also automatically enabled. | |
5973cafb | 392 | |
71bfa161 JA |
393 | nrfiles=int Number of files to use for this job. Defaults to 1. |
394 | ||
390b1537 JA |
395 | openfiles=int Number of files to keep open at the same time. Defaults to |
396 | the same as nrfiles, can be set smaller to limit the number | |
397 | simultaneous opens. | |
398 | ||
5af1c6f3 JA |
399 | file_service_type=str Defines how fio decides which file from a job to |
400 | service next. The following types are defined: | |
401 | ||
402 | random Just choose a file at random. | |
403 | ||
404 | roundrobin Round robin over open files. This | |
405 | is the default. | |
406 | ||
a086c257 JA |
407 | sequential Finish one file before moving on to |
408 | the next. Multiple files can still be | |
409 | open depending on 'openfiles'. | |
410 | ||
1907dbc6 JA |
411 | The string can have a number appended, indicating how |
412 | often to switch to a new file. So if option random:4 is | |
413 | given, fio will switch to a new random file after 4 ios | |
414 | have been issued. | |
415 | ||
71bfa161 JA |
416 | ioengine=str Defines how the job issues io to the file. The following |
417 | types are defined: | |
418 | ||
419 | sync Basic read(2) or write(2) io. lseek(2) is | |
420 | used to position the io location. | |
421 | ||
a31041ea | 422 | psync Basic pread(2) or pwrite(2) io. |
423 | ||
e05af9e5 | 424 | vsync Basic readv(2) or writev(2) IO. |
1d2af02a | 425 | |
15d182aa JA |
426 | libaio Linux native asynchronous io. Note that Linux |
427 | may only support queued behaviour with | |
428 | non-buffered IO (set direct=1 or buffered=0). | |
71bfa161 JA |
429 | |
430 | posixaio glibc posix asynchronous io. | |
431 | ||
417f0068 JA |
432 | solarisaio Solaris native asynchronous io. |
433 | ||
71bfa161 JA |
434 | mmap File is memory mapped and data copied |
435 | to/from using memcpy(3). | |
436 | ||
437 | splice splice(2) is used to transfer the data and | |
438 | vmsplice(2) to transfer data from user | |
439 | space to the kernel. | |
440 | ||
d0ff85df JA |
441 | syslet-rw Use the syslet system calls to make |
442 | regular read/write async. | |
443 | ||
71bfa161 | 444 | sg SCSI generic sg v3 io. May either be |
6c219763 | 445 | synchronous using the SG_IO ioctl, or if |
71bfa161 JA |
446 | the target is an sg character device |
447 | we use read(2) and write(2) for asynchronous | |
448 | io. | |
449 | ||
a94ea28b JA |
450 | null Doesn't transfer any data, just pretends |
451 | to. This is mainly used to exercise fio | |
452 | itself and for debugging/testing purposes. | |
453 | ||
ed92ac0c JA |
454 | net Transfer over the network to given host:port. |
455 | 'filename' must be set appropriately to | |
414c2a3e | 456 | filename=host/port/protocol regardless of send |
ed92ac0c | 457 | or receive, if the latter only the port |
414c2a3e JA |
458 | argument is used. 'host' may be an IP address |
459 | or hostname, port is the port number to be used, | |
460 | and protocol may be 'udp' or 'tcp'. If no | |
461 | protocol is given, TCP is used. | |
ed92ac0c | 462 | |
9cce02e8 JA |
463 | netsplice Like net, but uses splice/vmsplice to |
464 | map data and send/receive. | |
465 | ||
53aec0a4 | 466 | cpuio Doesn't transfer any data, but burns CPU |
ba0fbe10 JA |
467 | cycles according to the cpuload= and |
468 | cpucycle= options. Setting cpuload=85 | |
469 | will cause that job to do nothing but burn | |
36ecec83 GP |
470 | 85% of the CPU. In case of SMP machines, |
471 | use numjobs=<no_of_cpu> to get desired CPU | |
472 | usage, as the cpuload only loads a single | |
473 | CPU at the desired rate. | |
ba0fbe10 | 474 | |
e9a1806f JA |
475 | guasi The GUASI IO engine is the Generic Userspace |
476 | Asyncronous Syscall Interface approach | |
477 | to async IO. See | |
478 | ||
479 | http://www.xmailserver.org/guasi-lib.html | |
480 | ||
481 | for more info on GUASI. | |
482 | ||
8a7bd877 JA |
483 | external Prefix to specify loading an external |
484 | IO engine object file. Append the engine | |
485 | filename, eg ioengine=external:/tmp/foo.o | |
486 | to load ioengine foo.o in /tmp. | |
487 | ||
71bfa161 JA |
488 | iodepth=int This defines how many io units to keep in flight against |
489 | the file. The default is 1 for each file defined in this | |
490 | job, can be overridden with a larger value for higher | |
491 | concurrency. | |
492 | ||
4950421a | 493 | iodepth_batch_submit=int |
cb5ab512 | 494 | iodepth_batch=int This defines how many pieces of IO to submit at once. |
89e820f6 JA |
495 | It defaults to 1 which means that we submit each IO |
496 | as soon as it is available, but can be raised to submit | |
497 | bigger batches of IO at the time. | |
cb5ab512 | 498 | |
4950421a JA |
499 | iodepth_batch_complete=int This defines how many pieces of IO to retrieve |
500 | at once. It defaults to 1 which means that we'll ask | |
501 | for a minimum of 1 IO in the retrieval process from | |
502 | the kernel. The IO retrieval will go on until we | |
503 | hit the limit set by iodepth_low. If this variable is | |
504 | set to 0, then fio will always check for completed | |
505 | events before queuing more IO. This helps reduce | |
506 | IO latency, at the cost of more retrieval system calls. | |
507 | ||
e916b390 JA |
508 | iodepth_low=int The low water mark indicating when to start filling |
509 | the queue again. Defaults to the same as iodepth, meaning | |
510 | that fio will attempt to keep the queue full at all times. | |
511 | If iodepth is set to eg 16 and iodepth_low is set to 4, then | |
512 | after fio has filled the queue of 16 requests, it will let | |
513 | the depth drain down to 4 before starting to fill it again. | |
514 | ||
71bfa161 | 515 | direct=bool If value is true, use non-buffered io. This is usually |
76a43db4 JA |
516 | O_DIRECT. |
517 | ||
518 | buffered=bool If value is true, use buffered io. This is the opposite | |
519 | of the 'direct' option. Defaults to true. | |
71bfa161 | 520 | |
f7fa2653 | 521 | offset=int Start io at the given offset in the file. The data before |
71bfa161 JA |
522 | the given offset will not be touched. This effectively |
523 | caps the file size at real_size - offset. | |
524 | ||
525 | fsync=int If writing to a file, issue a sync of the dirty data | |
526 | for every number of blocks given. For example, if you give | |
527 | 32 as a parameter, fio will sync the file for every 32 | |
528 | writes issued. If fio is using non-buffered io, we may | |
529 | not sync the file. The exception is the sg io engine, which | |
6c219763 | 530 | synchronizes the disk cache anyway. |
71bfa161 | 531 | |
5036fc1e JA |
532 | overwrite=bool If true, writes to a file will always overwrite existing |
533 | data. If the file doesn't already exist, it will be | |
534 | created before the write phase begins. If the file exists | |
535 | and is large enough for the specified write phase, nothing | |
536 | will be done. | |
71bfa161 JA |
537 | |
538 | end_fsync=bool If true, fsync file contents when the job exits. | |
539 | ||
ebb1415f JA |
540 | fsync_on_close=bool If true, fio will fsync() a dirty file on close. |
541 | This differs from end_fsync in that it will happen on every | |
542 | file close, not just at the end of the job. | |
543 | ||
71bfa161 JA |
544 | rwmixread=int How large a percentage of the mix should be reads. |
545 | ||
546 | rwmixwrite=int How large a percentage of the mix should be writes. If both | |
547 | rwmixread and rwmixwrite is given and the values do not add | |
548 | up to 100%, the latter of the two will be used to override | |
549 | the first. | |
550 | ||
bb8895e0 JA |
551 | norandommap Normally fio will cover every block of the file when doing |
552 | random IO. If this option is given, fio will just get a | |
553 | new random offset without looking at past io history. This | |
554 | means that some blocks may not be read or written, and that | |
555 | some blocks may be read/written more than once. This option | |
8347239a JA |
556 | is mutually exclusive with verify= if and only if multiple |
557 | blocksizes (via bsrange=) are used, since fio only tracks | |
558 | complete rewrites of blocks. | |
bb8895e0 | 559 | |
2b386d25 JA |
560 | softrandommap See norandommap. If fio runs with the random block map enabled |
561 | and it fails to allocate the map, if this option is set it | |
562 | will continue without a random block map. As coverage will | |
563 | not be as complete as with random maps, this option is | |
564 | disabled by default. | |
565 | ||
71bfa161 JA |
566 | nice=int Run the job with the given nice value. See man nice(2). |
567 | ||
568 | prio=int Set the io priority value of this job. Linux limits us to | |
569 | a positive value between 0 and 7, with 0 being the highest. | |
570 | See man ionice(1). | |
571 | ||
572 | prioclass=int Set the io priority class. See man ionice(1). | |
573 | ||
574 | thinktime=int Stall the job x microseconds after an io has completed before | |
575 | issuing the next. May be used to simulate processing being | |
48097d5c JA |
576 | done by an application. See thinktime_blocks and |
577 | thinktime_spin. | |
578 | ||
579 | thinktime_spin=int | |
580 | Only valid if thinktime is set - pretend to spend CPU time | |
581 | doing something with the data received, before falling back | |
582 | to sleeping for the rest of the period specified by | |
583 | thinktime. | |
9c1f7434 JA |
584 | |
585 | thinktime_blocks | |
586 | Only valid if thinktime is set - control how many blocks | |
587 | to issue, before waiting 'thinktime' usecs. If not set, | |
588 | defaults to 1 which will make fio wait 'thinktime' usecs | |
589 | after every block. | |
71bfa161 JA |
590 | |
591 | rate=int Cap the bandwidth used by this job to this number of KiB/sec. | |
592 | ||
593 | ratemin=int Tell fio to do whatever it can to maintain at least this | |
4e991c23 JA |
594 | bandwidth. Failing to meet this requirement, will cause |
595 | the job to exit. | |
596 | ||
597 | rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same | |
598 | as rate, just specified independently of bandwidth. If the | |
599 | job is given a block size range instead of a fixed value, | |
600 | the smallest block size is used as the metric. | |
601 | ||
602 | rate_iops_min=int If fio doesn't meet this rate of IO, it will cause | |
603 | the job to exit. | |
71bfa161 JA |
604 | |
605 | ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number | |
6c219763 | 606 | of milliseconds. |
71bfa161 JA |
607 | |
608 | cpumask=int Set the CPU affinity of this job. The parameter given is a | |
a08bc17f JA |
609 | bitmask of allowed CPU's the job may run on. So if you want |
610 | the allowed CPUs to be 1 and 5, you would pass the decimal | |
611 | value of (1 << 1 | 1 << 5), or 34. See man | |
7dbb6eba | 612 | sched_setaffinity(2). This may not work on all supported |
b0ea08ce JA |
613 | operating systems or kernel versions. This option doesn't |
614 | work well for a higher CPU count than what you can store in | |
615 | an integer mask, so it can only control cpus 1-32. For | |
616 | boxes with larger CPU counts, use cpus_allowed. | |
71bfa161 | 617 | |
d2e268b0 JA |
618 | cpus_allowed=str Controls the same options as cpumask, but it allows a text |
619 | setting of the permitted CPUs instead. So to use CPUs 1 and | |
62a7273d JA |
620 | 5, you would specify cpus_allowed=1,5. This options also |
621 | allows a range of CPUs. Say you wanted a binding to CPUs | |
622 | 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15. | |
d2e268b0 | 623 | |
e417fd66 | 624 | startdelay=time Start this job the specified number of seconds after fio |
71bfa161 JA |
625 | has started. Only useful if the job file contains several |
626 | jobs, and you want to delay starting some jobs to a certain | |
627 | time. | |
628 | ||
e417fd66 | 629 | runtime=time Tell fio to terminate processing after the specified number |
71bfa161 JA |
630 | of seconds. It can be quite hard to determine for how long |
631 | a specified job will run, so this parameter is handy to | |
632 | cap the total runtime to a given time. | |
633 | ||
cf4464ca | 634 | time_based If set, fio will run for the duration of the runtime |
bf9a3edb | 635 | specified even if the file(s) are completely read or |
cf4464ca JA |
636 | written. It will simply loop over the same workload |
637 | as many times as the runtime allows. | |
638 | ||
e417fd66 | 639 | ramp_time=time If set, fio will run the specified workload for this amount |
721938ae JA |
640 | of time before logging any performance numbers. Useful for |
641 | letting performance settle before logging results, thus | |
b29ee5b3 JA |
642 | minimizing the runtime required for stable results. Note |
643 | that the ramp_time is considered lead in time for a job, | |
644 | thus it will increase the total runtime if a special timeout | |
645 | or runtime is specified. | |
721938ae | 646 | |
71bfa161 JA |
647 | invalidate=bool Invalidate the buffer/page cache parts for this file prior |
648 | to starting io. Defaults to true. | |
649 | ||
650 | sync=bool Use sync io for buffered writes. For the majority of the | |
651 | io engines, this means using O_SYNC. | |
652 | ||
d3aad8f2 | 653 | iomem=str |
71bfa161 JA |
654 | mem=str Fio can use various types of memory as the io unit buffer. |
655 | The allowed values are: | |
656 | ||
657 | malloc Use memory from malloc(3) as the buffers. | |
658 | ||
659 | shm Use shared memory as the buffers. Allocated | |
660 | through shmget(2). | |
661 | ||
74b025b0 JA |
662 | shmhuge Same as shm, but use huge pages as backing. |
663 | ||
313cb206 JA |
664 | mmap Use mmap to allocate buffers. May either be |
665 | anonymous memory, or can be file backed if | |
666 | a filename is given after the option. The | |
667 | format is mem=mmap:/path/to/file. | |
71bfa161 | 668 | |
d0bdaf49 JA |
669 | mmaphuge Use a memory mapped huge file as the buffer |
670 | backing. Append filename after mmaphuge, ala | |
671 | mem=mmaphuge:/hugetlbfs/file | |
672 | ||
71bfa161 | 673 | The area allocated is a function of the maximum allowed |
5394ae5f JA |
674 | bs size for the job, multiplied by the io depth given. Note |
675 | that for shmhuge and mmaphuge to work, the system must have | |
676 | free huge pages allocated. This can normally be checked | |
677 | and set by reading/writing /proc/sys/vm/nr_hugepages on a | |
678 | Linux system. Fio assumes a huge page is 4MiB in size. So | |
679 | to calculate the number of huge pages you need for a given | |
680 | job file, add up the io depth of all jobs (normally one unless | |
681 | iodepth= is used) and multiply by the maximum bs set. Then | |
682 | divide that number by the huge page size. You can see the | |
683 | size of the huge pages in /proc/meminfo. If no huge pages | |
684 | are allocated by having a non-zero number in nr_hugepages, | |
56bb17f2 | 685 | using mmaphuge or shmhuge will fail. Also see hugepage-size. |
5394ae5f JA |
686 | |
687 | mmaphuge also needs to have hugetlbfs mounted and the file | |
688 | location should point there. So if it's mounted in /huge, | |
689 | you would use mem=mmaphuge:/huge/somefile. | |
71bfa161 | 690 | |
f7fa2653 | 691 | hugepage-size=int |
56bb17f2 JA |
692 | Defines the size of a huge page. Must at least be equal |
693 | to the system setting, see /proc/meminfo. Defaults to 4MiB. | |
c51074e7 JA |
694 | Should probably always be a multiple of megabytes, so using |
695 | hugepage-size=Xm is the preferred way to set this to avoid | |
696 | setting a non-pow-2 bad value. | |
56bb17f2 | 697 | |
71bfa161 JA |
698 | exitall When one job finishes, terminate the rest. The default is |
699 | to wait for each job to finish, sometimes that is not the | |
700 | desired action. | |
701 | ||
702 | bwavgtime=int Average the calculated bandwidth over the given time. Value | |
6c219763 | 703 | is specified in milliseconds. |
71bfa161 JA |
704 | |
705 | create_serialize=bool If true, serialize the file creating for the jobs. | |
706 | This may be handy to avoid interleaving of data | |
707 | files, which may greatly depend on the filesystem | |
708 | used and even the number of processors in the system. | |
709 | ||
710 | create_fsync=bool fsync the data file after creation. This is the | |
711 | default. | |
712 | ||
814452bd JA |
713 | create_on_open=bool Don't pre-setup the files for IO, just create open() |
714 | when it's time to do IO to that file. | |
715 | ||
e545a6ce | 716 | unlink=bool Unlink the job files when done. Not the default, as repeated |
bf9a3edb JA |
717 | runs of that job would then waste time recreating the file |
718 | set again and again. | |
71bfa161 JA |
719 | |
720 | loops=int Run the specified number of iterations of this job. Used | |
721 | to repeat the same workload a given number of times. Defaults | |
722 | to 1. | |
723 | ||
68e1f29a | 724 | do_verify=bool Run the verify phase after a write phase. Only makes sense if |
e84c73a8 SL |
725 | verify is set. Defaults to 1. |
726 | ||
71bfa161 JA |
727 | verify=str If writing to a file, fio can verify the file contents |
728 | after each iteration of the job. The allowed values are: | |
729 | ||
730 | md5 Use an md5 sum of the data area and store | |
731 | it in the header of each block. | |
732 | ||
17dc34df JA |
733 | crc64 Use an experimental crc64 sum of the data |
734 | area and store it in the header of each | |
735 | block. | |
736 | ||
bac39e0e JA |
737 | crc32c Use a crc32c sum of the data area and store |
738 | it in the header of each block. | |
739 | ||
3845591f JA |
740 | crc32c-intel Use hardware assisted crc32c calcuation |
741 | provided on SSE4.2 enabled processors. | |
742 | ||
71bfa161 JA |
743 | crc32 Use a crc32 sum of the data area and store |
744 | it in the header of each block. | |
745 | ||
969f7ed3 JA |
746 | crc16 Use a crc16 sum of the data area and store |
747 | it in the header of each block. | |
748 | ||
17dc34df JA |
749 | crc7 Use a crc7 sum of the data area and store |
750 | it in the header of each block. | |
751 | ||
cd14cc10 JA |
752 | sha512 Use sha512 as the checksum function. |
753 | ||
754 | sha256 Use sha256 as the checksum function. | |
755 | ||
7437ee87 SL |
756 | meta Write extra information about each io |
757 | (timestamp, block number etc.). The block | |
758 | number is verified. | |
759 | ||
36690c9b JA |
760 | null Only pretend to verify. Useful for testing |
761 | internals with ioengine=null, not for much | |
762 | else. | |
763 | ||
6c219763 | 764 | This option can be used for repeated burn-in tests of a |
71bfa161 JA |
765 | system to make sure that the written data is also |
766 | correctly read back. | |
767 | ||
160b966d JA |
768 | verifysort=bool If set, fio will sort written verify blocks when it deems |
769 | it faster to read them back in a sorted manner. This is | |
770 | often the case when overwriting an existing file, since | |
771 | the blocks are already laid out in the file system. You | |
772 | can ignore this option unless doing huge amounts of really | |
773 | fast IO where the red-black tree sorting CPU time becomes | |
774 | significant. | |
3f9f4e26 | 775 | |
f7fa2653 | 776 | verify_offset=int Swap the verification header with data somewhere else |
546a9142 SL |
777 | in the block before writing. Its swapped back before |
778 | verifying. | |
779 | ||
f7fa2653 | 780 | verify_interval=int Write the verification header at a finer granularity |
3f9f4e26 SL |
781 | than the blocksize. It will be written for chunks the |
782 | size of header_interval. blocksize should divide this | |
783 | evenly. | |
90059d65 | 784 | |
e28218f3 SL |
785 | verify_pattern=int If set, fio will fill the io buffers with this |
786 | pattern. Fio defaults to filling with totally random | |
787 | bytes, but sometimes it's interesting to fill with a known | |
788 | pattern for io verification purposes. Depending on the | |
789 | width of the pattern, fio will fill 1/2/3/4 bytes of the | |
790 | buffer at the time. The verify_pattern cannot be larger than | |
791 | a 32-bit quantity. | |
792 | ||
68e1f29a | 793 | verify_fatal=bool Normally fio will keep checking the entire contents |
a12a3b4d JA |
794 | before quitting on a block verification failure. If this |
795 | option is set, fio will exit the job on the first observed | |
796 | failure. | |
160b966d | 797 | |
71bfa161 JA |
798 | stonewall Wait for preceeding jobs in the job file to exit, before |
799 | starting this one. Can be used to insert serialization | |
b3d62a75 JA |
800 | points in the job file. A stone wall also implies starting |
801 | a new reporting group. | |
802 | ||
803 | new_group Start a new reporting group. If this option isn't given, | |
804 | jobs in a file will be part of the same reporting group | |
bf9a3edb | 805 | unless separated by a stone wall (or if it's a group |
b3d62a75 | 806 | by itself, with the numjobs option). |
71bfa161 JA |
807 | |
808 | numjobs=int Create the specified number of clones of this job. May be | |
809 | used to setup a larger number of threads/processes doing | |
fa28c85a JA |
810 | the same thing. We regard that grouping of jobs as a |
811 | specific group. | |
812 | ||
813 | group_reporting If 'numjobs' is set, it may be interesting to display | |
814 | statistics for the group as a whole instead of for each | |
815 | individual job. This is especially true of 'numjobs' is | |
816 | large, looking at individual thread/process output quickly | |
817 | becomes unwieldy. If 'group_reporting' is specified, fio | |
818 | will show the final report per-group instead of per-job. | |
71bfa161 JA |
819 | |
820 | thread fio defaults to forking jobs, however if this option is | |
821 | given, fio will use pthread_create(3) to create threads | |
822 | instead. | |
823 | ||
f7fa2653 | 824 | zonesize=int Divide a file into zones of the specified size. See zoneskip. |
71bfa161 | 825 | |
f7fa2653 | 826 | zoneskip=int Skip the specified number of bytes when zonesize data has |
71bfa161 JA |
827 | been read. The two zone options can be used to only do |
828 | io on zones of a file. | |
829 | ||
076efc7c JA |
830 | write_iolog=str Write the issued io patterns to the specified file. See |
831 | read_iolog. | |
71bfa161 | 832 | |
076efc7c | 833 | read_iolog=str Open an iolog with the specified file name and replay the |
71bfa161 | 834 | io patterns it contains. This can be used to store a |
6df8adaa JA |
835 | workload and replay it sometime later. The iolog given |
836 | may also be a blktrace binary file, which allows fio | |
837 | to replay a workload captured by blktrace. See blktrace | |
838 | for how to capture such logging data. For blktrace replay, | |
839 | the file needs to be turned into a blkparse binary data | |
840 | file first (blktrace <device> -d file_for_fio.bin). | |
71bfa161 | 841 | |
e3cedca7 | 842 | write_bw_log=str If given, write a bandwidth log of the jobs in this job |
71bfa161 | 843 | file. Can be used to store data of the bandwidth of the |
e0da9bc2 JA |
844 | jobs in their lifetime. The included fio_generate_plots |
845 | script uses gnuplot to turn these text files into nice | |
e3cedca7 JA |
846 | graphs. See write_log_log for behaviour of given |
847 | filename. For this option, the postfix is _bw.log. | |
71bfa161 | 848 | |
e3cedca7 JA |
849 | write_lat_log=str Same as write_bw_log, except that this option stores io |
850 | completion latencies instead. If no filename is given | |
851 | with this option, the default filename of "jobname_type.log" | |
852 | is used. Even if the filename is given, fio will still | |
853 | append the type of log. So if one specifies | |
854 | ||
855 | write_lat_log=foo | |
856 | ||
857 | The actual log names will be foo_clat.log and foo_slat.log. | |
858 | This helps fio_generate_plot fine the logs automatically. | |
71bfa161 | 859 | |
f7fa2653 | 860 | lockmem=int Pin down the specified amount of memory with mlock(2). Can |
71bfa161 JA |
861 | potentially be used instead of removing memory or booting |
862 | with less memory to simulate a smaller amount of memory. | |
863 | ||
864 | exec_prerun=str Before running this job, issue the command specified | |
865 | through system(3). | |
866 | ||
867 | exec_postrun=str After the job completes, issue the command specified | |
868 | though system(3). | |
869 | ||
870 | ioscheduler=str Attempt to switch the device hosting the file to the specified | |
871 | io scheduler before running. | |
872 | ||
873 | cpuload=int If the job is a CPU cycle eater, attempt to use the specified | |
874 | percentage of CPU cycles. | |
875 | ||
876 | cpuchunks=int If the job is a CPU cycle eater, split the load into | |
26eca2db | 877 | cycles of the given time. In microseconds. |
71bfa161 | 878 | |
0a839f30 JA |
879 | disk_util=bool Generate disk utilization statistics, if the platform |
880 | supports it. Defaults to on. | |
881 | ||
9520ebb9 JA |
882 | disable_clat=bool Disable measurements of completion latency numbers. Useful |
883 | only for cutting back the number of calls to gettimeofday, | |
884 | as that does impact performance at really high IOPS rates. | |
885 | Note that to really get rid of a large amount of these | |
886 | calls, this option must be used with disable_slat and | |
887 | disable_bw as well. | |
888 | ||
889 | disable_slat=bool Disable measurements of submission latency numbers. See | |
890 | disable_clat. | |
891 | ||
892 | disable_bw=bool Disable measurements of throughput/bandwidth numbers. See | |
893 | disable_clat. | |
894 | ||
993bf48b JA |
895 | gtod_reduce=bool Enable all of the gettimeofday() reducing options |
896 | (disable_clat, disable_slat, disable_bw) plus reduce | |
897 | precision of the timeout somewhat to really shrink | |
898 | the gettimeofday() call count. With this option enabled, | |
899 | we only do about 0.4% of the gtod() calls we would have | |
900 | done if all time keeping was enabled. | |
901 | ||
be4ecfdf JA |
902 | gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of |
903 | execution to just getting the current time. Fio (and | |
904 | databases, for instance) are very intensive on gettimeofday() | |
905 | calls. With this option, you can set one CPU aside for | |
906 | doing nothing but logging current time to a shared memory | |
907 | location. Then the other threads/processes that run IO | |
908 | workloads need only copy that segment, instead of entering | |
909 | the kernel with a gettimeofday() call. The CPU set aside | |
910 | for doing these time calls will be excluded from other | |
911 | uses. Fio will manually clear it from the CPU mask of other | |
912 | jobs. | |
913 | ||
71bfa161 JA |
914 | |
915 | 6.0 Interpreting the output | |
916 | --------------------------- | |
917 | ||
918 | fio spits out a lot of output. While running, fio will display the | |
919 | status of the jobs created. An example of that would be: | |
920 | ||
73c8b082 | 921 | Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s] |
71bfa161 JA |
922 | |
923 | The characters inside the square brackets denote the current status of | |
924 | each thread. The possible values (in typical life cycle order) are: | |
925 | ||
926 | Idle Run | |
927 | ---- --- | |
928 | P Thread setup, but not started. | |
929 | C Thread created. | |
930 | I Thread initialized, waiting. | |
931 | R Running, doing sequential reads. | |
932 | r Running, doing random reads. | |
933 | W Running, doing sequential writes. | |
934 | w Running, doing random writes. | |
935 | M Running, doing mixed sequential reads/writes. | |
936 | m Running, doing mixed random reads/writes. | |
937 | F Running, currently waiting for fsync() | |
fc6bd43c | 938 | V Running, doing verification of written data. |
71bfa161 JA |
939 | E Thread exited, not reaped by main thread yet. |
940 | _ Thread reaped. | |
941 | ||
942 | The other values are fairly self explanatory - number of threads | |
c9f60304 JA |
943 | currently running and doing io, rate of io since last check (read speed |
944 | listed first, then write speed), and the estimated completion percentage | |
945 | and time for the running group. It's impossible to estimate runtime of | |
946 | the following groups (if any). | |
71bfa161 JA |
947 | |
948 | When fio is done (or interrupted by ctrl-c), it will show the data for | |
949 | each thread, group of threads, and disks in that order. For each data | |
950 | direction, the output looks like: | |
951 | ||
952 | Client1 (g=0): err= 0: | |
953 | write: io= 32MiB, bw= 666KiB/s, runt= 50320msec | |
6104ddb6 JA |
954 | slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92 |
955 | clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82 | |
956 | bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68 | |
e7823a94 | 957 | cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17 |
71619dc2 | 958 | 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 |
959 | submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% |
960 | complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% | |
30061b97 | 961 | issued r/w: total=0/32768, short=0/0 |
8abdce66 JA |
962 | lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%, |
963 | lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0% | |
71bfa161 JA |
964 | |
965 | The client number is printed, along with the group id and error of that | |
966 | thread. Below is the io statistics, here for writes. In the order listed, | |
967 | they denote: | |
968 | ||
969 | io= Number of megabytes io performed | |
970 | bw= Average bandwidth rate | |
971 | runt= The runtime of that thread | |
72fbda2a | 972 | slat= Submission latency (avg being the average, stdev being the |
71bfa161 JA |
973 | standard deviation). This is the time it took to submit |
974 | the io. For sync io, the slat is really the completion | |
8a35c71e | 975 | latency, since queue/complete is one operation there. This |
bf9a3edb | 976 | value can be in milliseconds or microseconds, fio will choose |
8a35c71e | 977 | the most appropriate base and print that. In the example |
bf9a3edb | 978 | above, milliseconds is the best scale. |
71bfa161 JA |
979 | clat= Completion latency. Same names as slat, this denotes the |
980 | time from submission to completion of the io pieces. For | |
981 | sync io, clat will usually be equal (or very close) to 0, | |
982 | as the time from submit to complete is basically just | |
983 | CPU time (io has already been done, see slat explanation). | |
984 | bw= Bandwidth. Same names as the xlat stats, but also includes | |
985 | an approximate percentage of total aggregate bandwidth | |
986 | this thread received in this group. This last value is | |
987 | only really useful if the threads in this group are on the | |
988 | same disk, since they are then competing for disk access. | |
989 | cpu= CPU usage. User and system time, along with the number | |
e7823a94 JA |
990 | of context switches this thread went through, usage of |
991 | system and user time, and finally the number of major | |
992 | and minor page faults. | |
71619dc2 JA |
993 | IO depths= The distribution of io depths over the job life time. The |
994 | numbers are divided into powers of 2, so for example the | |
995 | 16= entries includes depths up to that value but higher | |
996 | than the previous entry. In other words, it covers the | |
997 | range from 16 to 31. | |
838bc709 JA |
998 | IO submit= How many pieces of IO were submitting in a single submit |
999 | call. Each entry denotes that amount and below, until | |
1000 | the previous entry - eg, 8=100% mean that we submitted | |
1001 | anywhere in between 5-8 ios per submit call. | |
1002 | IO complete= Like the above submit number, but for completions instead. | |
30061b97 JA |
1003 | IO issued= The number of read/write requests issued, and how many |
1004 | of them were short. | |
ec118304 JA |
1005 | IO latencies= The distribution of IO completion latencies. This is the |
1006 | time from when IO leaves fio and when it gets completed. | |
1007 | The numbers follow the same pattern as the IO depths, | |
1008 | meaning that 2=1.6% means that 1.6% of the IO completed | |
8abdce66 JA |
1009 | within 2 msecs, 20=12.8% means that 12.8% of the IO |
1010 | took more than 10 msecs, but less than (or equal to) 20 msecs. | |
71bfa161 JA |
1011 | |
1012 | After each client has been listed, the group statistics are printed. They | |
1013 | will look like this: | |
1014 | ||
1015 | Run status group 0 (all jobs): | |
1016 | READ: io=64MiB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec | |
1017 | WRITE: io=64MiB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec | |
1018 | ||
1019 | For each data direction, it prints: | |
1020 | ||
1021 | io= Number of megabytes io performed. | |
1022 | aggrb= Aggregate bandwidth of threads in this group. | |
1023 | minb= The minimum average bandwidth a thread saw. | |
1024 | maxb= The maximum average bandwidth a thread saw. | |
1025 | mint= The smallest runtime of the threads in that group. | |
1026 | maxt= The longest runtime of the threads in that group. | |
1027 | ||
1028 | And finally, the disk statistics are printed. They will look like this: | |
1029 | ||
1030 | Disk stats (read/write): | |
1031 | sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% | |
1032 | ||
1033 | Each value is printed for both reads and writes, with reads first. The | |
1034 | numbers denote: | |
1035 | ||
1036 | ios= Number of ios performed by all groups. | |
1037 | merge= Number of merges io the io scheduler. | |
1038 | ticks= Number of ticks we kept the disk busy. | |
1039 | io_queue= Total time spent in the disk queue. | |
1040 | util= The disk utilization. A value of 100% means we kept the disk | |
1041 | busy constantly, 50% would be a disk idling half of the time. | |
1042 | ||
1043 | ||
1044 | 7.0 Terse output | |
1045 | ---------------- | |
1046 | ||
1047 | For scripted usage where you typically want to generate tables or graphs | |
6af019c9 | 1048 | of the results, fio can output the results in a semicolon separated format. |
71bfa161 JA |
1049 | The format is one long line of values, such as: |
1050 | ||
6af019c9 JA |
1051 | client1;0;0;1906777;1090804;1790;0;0;0.000000;0.000000;0;0;0.000000;0.000000;929380;1152890;25.510151%;1078276.333333;128948.113404;0;0;0;0;0;0.000000;0.000000;0;0;0.000000;0.000000;0;0;0.000000%;0.000000;0.000000;100.000000%;0.000000%;324;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%;0.0%;100.0%;0.0%;0.0%;0.0%;0.0%;0.0% |
1052 | ;0.0%;0.0%;0.0%;0.0%;0.0% | |
71bfa161 | 1053 | |
6820cb3b JA |
1054 | To enable terse output, use the --minimal command line option. |
1055 | ||
71bfa161 JA |
1056 | Split up, the format is as follows: |
1057 | ||
1058 | jobname, groupid, error | |
1059 | READ status: | |
1060 | KiB IO, bandwidth (KiB/sec), runtime (msec) | |
1061 | Submission latency: min, max, mean, deviation | |
1062 | Completion latency: min, max, mean, deviation | |
6c219763 | 1063 | Bw: min, max, aggregate percentage of total, mean, deviation |
71bfa161 JA |
1064 | WRITE status: |
1065 | KiB IO, bandwidth (KiB/sec), runtime (msec) | |
1066 | Submission latency: min, max, mean, deviation | |
1067 | Completion latency: min, max, mean, deviation | |
6c219763 | 1068 | Bw: min, max, aggregate percentage of total, mean, deviation |
046ee302 | 1069 | CPU usage: user, system, context switches, major faults, minor faults |
2270890c JA |
1070 | IO depths: <=1, 2, 4, 8, 16, 32, >=64 |
1071 | IO latencies: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000 | |
1072 | Text description | |
71bfa161 | 1073 |