Commit | Line | Data |
---|---|---|
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 | ||
3776041e | 233 | directory=str Prefix filenames with this directory. Used to place files |
71bfa161 JA |
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 | ||
3776041e | 253 | lockfile=str Fio defaults to not locking any files before it does |
4d4e80f2 JA |
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). | |
3776041e | 306 | Unless specific nrfiles and filesize options are given, |
7616cafe JA |
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 | |
3ce9dcaf JA |
317 | sense with sequential write. For a read workload, the mount |
318 | point will be filled first then IO started on the result. | |
aa31f1f1 | 319 | |
f7fa2653 JA |
320 | blocksize=int |
321 | bs=int The block size used for the io units. Defaults to 4k. Values | |
322 | can be given for both read and writes. If a single int is | |
323 | given, it will apply to both. If a second int is specified | |
f90eff5a JA |
324 | after a comma, it will apply to writes only. In other words, |
325 | the format is either bs=read_and_write or bs=read,write. | |
326 | bs=4k,8k will thus use 4k blocks for reads, and 8k blocks | |
787f7e95 JA |
327 | for writes. If you only wish to set the write size, you |
328 | can do so by passing an empty read size - bs=,8k will set | |
329 | 8k for writes and leave the read default value. | |
a00735e6 | 330 | |
2b7a01d0 JA |
331 | blockalign=int |
332 | ba=int At what boundary to align random IO offsets. Defaults to | |
333 | the same as 'blocksize' the minimum blocksize given. | |
334 | Minimum alignment is typically 512b for using direct IO, | |
335 | though it usually depends on the hardware block size. This | |
336 | option is mutually exclusive with using a random map for | |
337 | files, so it will turn off that option. | |
338 | ||
d3aad8f2 | 339 | blocksize_range=irange |
71bfa161 JA |
340 | bsrange=irange Instead of giving a single block size, specify a range |
341 | and fio will mix the issued io block sizes. The issued | |
342 | io unit will always be a multiple of the minimum value | |
f90eff5a JA |
343 | given (also see bs_unaligned). Applies to both reads and |
344 | writes, however a second range can be given after a comma. | |
345 | See bs=. | |
a00735e6 | 346 | |
564ca972 JA |
347 | bssplit=str Sometimes you want even finer grained control of the |
348 | block sizes issued, not just an even split between them. | |
349 | This option allows you to weight various block sizes, | |
350 | so that you are able to define a specific amount of | |
351 | block sizes issued. The format for this option is: | |
352 | ||
353 | bssplit=blocksize/percentage:blocksize/percentage | |
354 | ||
355 | for as many block sizes as needed. So if you want to define | |
356 | a workload that has 50% 64k blocks, 10% 4k blocks, and | |
357 | 40% 32k blocks, you would write: | |
358 | ||
359 | bssplit=4k/10:64k/50:32k/40 | |
360 | ||
361 | Ordering does not matter. If the percentage is left blank, | |
362 | fio will fill in the remaining values evenly. So a bssplit | |
363 | option like this one: | |
364 | ||
365 | bssplit=4k/50:1k/:32k/ | |
366 | ||
367 | would have 50% 4k ios, and 25% 1k and 32k ios. The percentages | |
368 | always add up to 100, if bssplit is given a range that adds | |
369 | up to more, it will error out. | |
370 | ||
720e84ad JA |
371 | bssplit also supports giving separate splits to reads and |
372 | writes. The format is identical to what bs= accepts. You | |
373 | have to separate the read and write parts with a comma. So | |
374 | if you want a workload that has 50% 2k reads and 50% 4k reads, | |
375 | while having 90% 4k writes and 10% 8k writes, you would | |
376 | specify: | |
377 | ||
378 | bssplit=2k/50:4k/50,4k/90,8k/10 | |
379 | ||
d3aad8f2 | 380 | blocksize_unaligned |
690adba3 JA |
381 | bs_unaligned If this option is given, any byte size value within bsrange |
382 | may be used as a block range. This typically wont work with | |
383 | direct IO, as that normally requires sector alignment. | |
71bfa161 | 384 | |
e9459e5a JA |
385 | zero_buffers If this option is given, fio will init the IO buffers to |
386 | all zeroes. The default is to fill them with random data. | |
387 | ||
5973cafb JA |
388 | refill_buffers If this option is given, fio will refill the IO buffers |
389 | on every submit. The default is to only fill it at init | |
390 | time and reuse that data. Only makes sense if zero_buffers | |
41ccd845 JA |
391 | isn't specified, naturally. If data verification is enabled, |
392 | refill_buffers is also automatically enabled. | |
5973cafb | 393 | |
71bfa161 JA |
394 | nrfiles=int Number of files to use for this job. Defaults to 1. |
395 | ||
390b1537 JA |
396 | openfiles=int Number of files to keep open at the same time. Defaults to |
397 | the same as nrfiles, can be set smaller to limit the number | |
398 | simultaneous opens. | |
399 | ||
5af1c6f3 JA |
400 | file_service_type=str Defines how fio decides which file from a job to |
401 | service next. The following types are defined: | |
402 | ||
403 | random Just choose a file at random. | |
404 | ||
405 | roundrobin Round robin over open files. This | |
406 | is the default. | |
407 | ||
a086c257 JA |
408 | sequential Finish one file before moving on to |
409 | the next. Multiple files can still be | |
410 | open depending on 'openfiles'. | |
411 | ||
1907dbc6 JA |
412 | The string can have a number appended, indicating how |
413 | often to switch to a new file. So if option random:4 is | |
414 | given, fio will switch to a new random file after 4 ios | |
415 | have been issued. | |
416 | ||
71bfa161 JA |
417 | ioengine=str Defines how the job issues io to the file. The following |
418 | types are defined: | |
419 | ||
420 | sync Basic read(2) or write(2) io. lseek(2) is | |
421 | used to position the io location. | |
422 | ||
a31041ea | 423 | psync Basic pread(2) or pwrite(2) io. |
424 | ||
e05af9e5 | 425 | vsync Basic readv(2) or writev(2) IO. |
1d2af02a | 426 | |
15d182aa JA |
427 | libaio Linux native asynchronous io. Note that Linux |
428 | may only support queued behaviour with | |
429 | non-buffered IO (set direct=1 or buffered=0). | |
71bfa161 JA |
430 | |
431 | posixaio glibc posix asynchronous io. | |
432 | ||
417f0068 JA |
433 | solarisaio Solaris native asynchronous io. |
434 | ||
71bfa161 JA |
435 | mmap File is memory mapped and data copied |
436 | to/from using memcpy(3). | |
437 | ||
438 | splice splice(2) is used to transfer the data and | |
439 | vmsplice(2) to transfer data from user | |
440 | space to the kernel. | |
441 | ||
d0ff85df JA |
442 | syslet-rw Use the syslet system calls to make |
443 | regular read/write async. | |
444 | ||
71bfa161 | 445 | sg SCSI generic sg v3 io. May either be |
6c219763 | 446 | synchronous using the SG_IO ioctl, or if |
71bfa161 JA |
447 | the target is an sg character device |
448 | we use read(2) and write(2) for asynchronous | |
449 | io. | |
450 | ||
a94ea28b JA |
451 | null Doesn't transfer any data, just pretends |
452 | to. This is mainly used to exercise fio | |
453 | itself and for debugging/testing purposes. | |
454 | ||
ed92ac0c JA |
455 | net Transfer over the network to given host:port. |
456 | 'filename' must be set appropriately to | |
414c2a3e | 457 | filename=host/port/protocol regardless of send |
ed92ac0c | 458 | or receive, if the latter only the port |
414c2a3e JA |
459 | argument is used. 'host' may be an IP address |
460 | or hostname, port is the port number to be used, | |
461 | and protocol may be 'udp' or 'tcp'. If no | |
462 | protocol is given, TCP is used. | |
ed92ac0c | 463 | |
9cce02e8 JA |
464 | netsplice Like net, but uses splice/vmsplice to |
465 | map data and send/receive. | |
466 | ||
53aec0a4 | 467 | cpuio Doesn't transfer any data, but burns CPU |
ba0fbe10 JA |
468 | cycles according to the cpuload= and |
469 | cpucycle= options. Setting cpuload=85 | |
470 | will cause that job to do nothing but burn | |
36ecec83 GP |
471 | 85% of the CPU. In case of SMP machines, |
472 | use numjobs=<no_of_cpu> to get desired CPU | |
473 | usage, as the cpuload only loads a single | |
474 | CPU at the desired rate. | |
ba0fbe10 | 475 | |
e9a1806f JA |
476 | guasi The GUASI IO engine is the Generic Userspace |
477 | Asyncronous Syscall Interface approach | |
478 | to async IO. See | |
479 | ||
480 | http://www.xmailserver.org/guasi-lib.html | |
481 | ||
482 | for more info on GUASI. | |
483 | ||
8a7bd877 JA |
484 | external Prefix to specify loading an external |
485 | IO engine object file. Append the engine | |
486 | filename, eg ioengine=external:/tmp/foo.o | |
487 | to load ioengine foo.o in /tmp. | |
488 | ||
71bfa161 JA |
489 | iodepth=int This defines how many io units to keep in flight against |
490 | the file. The default is 1 for each file defined in this | |
491 | job, can be overridden with a larger value for higher | |
492 | concurrency. | |
493 | ||
4950421a | 494 | iodepth_batch_submit=int |
cb5ab512 | 495 | iodepth_batch=int This defines how many pieces of IO to submit at once. |
89e820f6 JA |
496 | It defaults to 1 which means that we submit each IO |
497 | as soon as it is available, but can be raised to submit | |
498 | bigger batches of IO at the time. | |
cb5ab512 | 499 | |
4950421a JA |
500 | iodepth_batch_complete=int This defines how many pieces of IO to retrieve |
501 | at once. It defaults to 1 which means that we'll ask | |
502 | for a minimum of 1 IO in the retrieval process from | |
503 | the kernel. The IO retrieval will go on until we | |
504 | hit the limit set by iodepth_low. If this variable is | |
505 | set to 0, then fio will always check for completed | |
506 | events before queuing more IO. This helps reduce | |
507 | IO latency, at the cost of more retrieval system calls. | |
508 | ||
e916b390 JA |
509 | iodepth_low=int The low water mark indicating when to start filling |
510 | the queue again. Defaults to the same as iodepth, meaning | |
511 | that fio will attempt to keep the queue full at all times. | |
512 | If iodepth is set to eg 16 and iodepth_low is set to 4, then | |
513 | after fio has filled the queue of 16 requests, it will let | |
514 | the depth drain down to 4 before starting to fill it again. | |
515 | ||
71bfa161 | 516 | direct=bool If value is true, use non-buffered io. This is usually |
76a43db4 JA |
517 | O_DIRECT. |
518 | ||
519 | buffered=bool If value is true, use buffered io. This is the opposite | |
520 | of the 'direct' option. Defaults to true. | |
71bfa161 | 521 | |
f7fa2653 | 522 | offset=int Start io at the given offset in the file. The data before |
71bfa161 JA |
523 | the given offset will not be touched. This effectively |
524 | caps the file size at real_size - offset. | |
525 | ||
526 | fsync=int If writing to a file, issue a sync of the dirty data | |
527 | for every number of blocks given. For example, if you give | |
528 | 32 as a parameter, fio will sync the file for every 32 | |
529 | writes issued. If fio is using non-buffered io, we may | |
530 | not sync the file. The exception is the sg io engine, which | |
6c219763 | 531 | synchronizes the disk cache anyway. |
71bfa161 | 532 | |
5f9099ea JA |
533 | fsyncdata=int Like fsync= but uses fdatasync() to only sync data and not |
534 | metadata blocks. | |
535 | ||
5036fc1e JA |
536 | overwrite=bool If true, writes to a file will always overwrite existing |
537 | data. If the file doesn't already exist, it will be | |
538 | created before the write phase begins. If the file exists | |
539 | and is large enough for the specified write phase, nothing | |
540 | will be done. | |
71bfa161 JA |
541 | |
542 | end_fsync=bool If true, fsync file contents when the job exits. | |
543 | ||
ebb1415f JA |
544 | fsync_on_close=bool If true, fio will fsync() a dirty file on close. |
545 | This differs from end_fsync in that it will happen on every | |
546 | file close, not just at the end of the job. | |
547 | ||
71bfa161 JA |
548 | rwmixread=int How large a percentage of the mix should be reads. |
549 | ||
550 | rwmixwrite=int How large a percentage of the mix should be writes. If both | |
551 | rwmixread and rwmixwrite is given and the values do not add | |
552 | up to 100%, the latter of the two will be used to override | |
c35dd7a6 JA |
553 | the first. This may interfere with a given rate setting, |
554 | if fio is asked to limit reads or writes to a certain rate. | |
555 | If that is the case, then the distribution may be skewed. | |
71bfa161 | 556 | |
bb8895e0 JA |
557 | norandommap Normally fio will cover every block of the file when doing |
558 | random IO. If this option is given, fio will just get a | |
559 | new random offset without looking at past io history. This | |
560 | means that some blocks may not be read or written, and that | |
561 | some blocks may be read/written more than once. This option | |
8347239a JA |
562 | is mutually exclusive with verify= if and only if multiple |
563 | blocksizes (via bsrange=) are used, since fio only tracks | |
564 | complete rewrites of blocks. | |
bb8895e0 | 565 | |
2b386d25 JA |
566 | softrandommap See norandommap. If fio runs with the random block map enabled |
567 | and it fails to allocate the map, if this option is set it | |
568 | will continue without a random block map. As coverage will | |
569 | not be as complete as with random maps, this option is | |
570 | disabled by default. | |
571 | ||
71bfa161 JA |
572 | nice=int Run the job with the given nice value. See man nice(2). |
573 | ||
574 | prio=int Set the io priority value of this job. Linux limits us to | |
575 | a positive value between 0 and 7, with 0 being the highest. | |
576 | See man ionice(1). | |
577 | ||
578 | prioclass=int Set the io priority class. See man ionice(1). | |
579 | ||
580 | thinktime=int Stall the job x microseconds after an io has completed before | |
581 | issuing the next. May be used to simulate processing being | |
48097d5c JA |
582 | done by an application. See thinktime_blocks and |
583 | thinktime_spin. | |
584 | ||
585 | thinktime_spin=int | |
586 | Only valid if thinktime is set - pretend to spend CPU time | |
587 | doing something with the data received, before falling back | |
588 | to sleeping for the rest of the period specified by | |
589 | thinktime. | |
9c1f7434 JA |
590 | |
591 | thinktime_blocks | |
592 | Only valid if thinktime is set - control how many blocks | |
593 | to issue, before waiting 'thinktime' usecs. If not set, | |
594 | defaults to 1 which will make fio wait 'thinktime' usecs | |
595 | after every block. | |
71bfa161 | 596 | |
581e7141 JA |
597 | rate=int Cap the bandwidth used by this job. The number is in bytes/sec, |
598 | the normal postfix rules apply. You can use rate=500k to limit | |
599 | reads and writes to 500k each, or you can specify read and | |
600 | writes separately. Using rate=1m,500k would limit reads to | |
601 | 1MB/sec and writes to 500KB/sec. Capping only reads or | |
602 | writes can be done with rate=,500k or rate=500k,. The former | |
603 | will only limit writes (to 500KB/sec), the latter will only | |
604 | limit reads. | |
71bfa161 JA |
605 | |
606 | ratemin=int Tell fio to do whatever it can to maintain at least this | |
4e991c23 | 607 | bandwidth. Failing to meet this requirement, will cause |
581e7141 JA |
608 | the job to exit. The same format as rate is used for |
609 | read vs write separation. | |
4e991c23 JA |
610 | |
611 | rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same | |
612 | as rate, just specified independently of bandwidth. If the | |
613 | job is given a block size range instead of a fixed value, | |
581e7141 JA |
614 | the smallest block size is used as the metric. The same format |
615 | as rate is used for read vs write seperation. | |
4e991c23 JA |
616 | |
617 | rate_iops_min=int If fio doesn't meet this rate of IO, it will cause | |
581e7141 JA |
618 | the job to exit. The same format as rate is used for read vs |
619 | write seperation. | |
71bfa161 JA |
620 | |
621 | ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number | |
6c219763 | 622 | of milliseconds. |
71bfa161 JA |
623 | |
624 | cpumask=int Set the CPU affinity of this job. The parameter given is a | |
a08bc17f JA |
625 | bitmask of allowed CPU's the job may run on. So if you want |
626 | the allowed CPUs to be 1 and 5, you would pass the decimal | |
627 | value of (1 << 1 | 1 << 5), or 34. See man | |
7dbb6eba | 628 | sched_setaffinity(2). This may not work on all supported |
b0ea08ce JA |
629 | operating systems or kernel versions. This option doesn't |
630 | work well for a higher CPU count than what you can store in | |
631 | an integer mask, so it can only control cpus 1-32. For | |
632 | boxes with larger CPU counts, use cpus_allowed. | |
71bfa161 | 633 | |
d2e268b0 JA |
634 | cpus_allowed=str Controls the same options as cpumask, but it allows a text |
635 | setting of the permitted CPUs instead. So to use CPUs 1 and | |
62a7273d JA |
636 | 5, you would specify cpus_allowed=1,5. This options also |
637 | allows a range of CPUs. Say you wanted a binding to CPUs | |
638 | 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15. | |
d2e268b0 | 639 | |
e417fd66 | 640 | startdelay=time Start this job the specified number of seconds after fio |
71bfa161 JA |
641 | has started. Only useful if the job file contains several |
642 | jobs, and you want to delay starting some jobs to a certain | |
643 | time. | |
644 | ||
e417fd66 | 645 | runtime=time Tell fio to terminate processing after the specified number |
71bfa161 JA |
646 | of seconds. It can be quite hard to determine for how long |
647 | a specified job will run, so this parameter is handy to | |
648 | cap the total runtime to a given time. | |
649 | ||
cf4464ca | 650 | time_based If set, fio will run for the duration of the runtime |
bf9a3edb | 651 | specified even if the file(s) are completely read or |
cf4464ca JA |
652 | written. It will simply loop over the same workload |
653 | as many times as the runtime allows. | |
654 | ||
e417fd66 | 655 | ramp_time=time If set, fio will run the specified workload for this amount |
721938ae JA |
656 | of time before logging any performance numbers. Useful for |
657 | letting performance settle before logging results, thus | |
b29ee5b3 JA |
658 | minimizing the runtime required for stable results. Note |
659 | that the ramp_time is considered lead in time for a job, | |
660 | thus it will increase the total runtime if a special timeout | |
661 | or runtime is specified. | |
721938ae | 662 | |
71bfa161 JA |
663 | invalidate=bool Invalidate the buffer/page cache parts for this file prior |
664 | to starting io. Defaults to true. | |
665 | ||
666 | sync=bool Use sync io for buffered writes. For the majority of the | |
667 | io engines, this means using O_SYNC. | |
668 | ||
d3aad8f2 | 669 | iomem=str |
71bfa161 JA |
670 | mem=str Fio can use various types of memory as the io unit buffer. |
671 | The allowed values are: | |
672 | ||
673 | malloc Use memory from malloc(3) as the buffers. | |
674 | ||
675 | shm Use shared memory as the buffers. Allocated | |
676 | through shmget(2). | |
677 | ||
74b025b0 JA |
678 | shmhuge Same as shm, but use huge pages as backing. |
679 | ||
313cb206 JA |
680 | mmap Use mmap to allocate buffers. May either be |
681 | anonymous memory, or can be file backed if | |
682 | a filename is given after the option. The | |
683 | format is mem=mmap:/path/to/file. | |
71bfa161 | 684 | |
d0bdaf49 JA |
685 | mmaphuge Use a memory mapped huge file as the buffer |
686 | backing. Append filename after mmaphuge, ala | |
687 | mem=mmaphuge:/hugetlbfs/file | |
688 | ||
71bfa161 | 689 | The area allocated is a function of the maximum allowed |
5394ae5f JA |
690 | bs size for the job, multiplied by the io depth given. Note |
691 | that for shmhuge and mmaphuge to work, the system must have | |
692 | free huge pages allocated. This can normally be checked | |
693 | and set by reading/writing /proc/sys/vm/nr_hugepages on a | |
694 | Linux system. Fio assumes a huge page is 4MiB in size. So | |
695 | to calculate the number of huge pages you need for a given | |
696 | job file, add up the io depth of all jobs (normally one unless | |
697 | iodepth= is used) and multiply by the maximum bs set. Then | |
698 | divide that number by the huge page size. You can see the | |
699 | size of the huge pages in /proc/meminfo. If no huge pages | |
700 | are allocated by having a non-zero number in nr_hugepages, | |
56bb17f2 | 701 | using mmaphuge or shmhuge will fail. Also see hugepage-size. |
5394ae5f JA |
702 | |
703 | mmaphuge also needs to have hugetlbfs mounted and the file | |
704 | location should point there. So if it's mounted in /huge, | |
705 | you would use mem=mmaphuge:/huge/somefile. | |
71bfa161 | 706 | |
d529ee19 JA |
707 | iomem_align=int This indiciates the memory alignment of the IO memory buffers. |
708 | Note that the given alignment is applied to the first IO unit | |
709 | buffer, if using iodepth the alignment of the following buffers | |
710 | are given by the bs used. In other words, if using a bs that is | |
711 | a multiple of the page sized in the system, all buffers will | |
712 | be aligned to this value. If using a bs that is not page | |
713 | aligned, the alignment of subsequent IO memory buffers is the | |
714 | sum of the iomem_align and bs used. | |
715 | ||
f7fa2653 | 716 | hugepage-size=int |
56bb17f2 JA |
717 | Defines the size of a huge page. Must at least be equal |
718 | to the system setting, see /proc/meminfo. Defaults to 4MiB. | |
c51074e7 JA |
719 | Should probably always be a multiple of megabytes, so using |
720 | hugepage-size=Xm is the preferred way to set this to avoid | |
721 | setting a non-pow-2 bad value. | |
56bb17f2 | 722 | |
71bfa161 JA |
723 | exitall When one job finishes, terminate the rest. The default is |
724 | to wait for each job to finish, sometimes that is not the | |
725 | desired action. | |
726 | ||
727 | bwavgtime=int Average the calculated bandwidth over the given time. Value | |
6c219763 | 728 | is specified in milliseconds. |
71bfa161 JA |
729 | |
730 | create_serialize=bool If true, serialize the file creating for the jobs. | |
731 | This may be handy to avoid interleaving of data | |
732 | files, which may greatly depend on the filesystem | |
733 | used and even the number of processors in the system. | |
734 | ||
735 | create_fsync=bool fsync the data file after creation. This is the | |
736 | default. | |
737 | ||
814452bd JA |
738 | create_on_open=bool Don't pre-setup the files for IO, just create open() |
739 | when it's time to do IO to that file. | |
740 | ||
afad68f7 | 741 | pre_read=bool If this is given, files will be pre-read into memory before |
34f1c044 JA |
742 | starting the given IO operation. This will also clear |
743 | the 'invalidate' flag, since it is pointless to pre-read | |
9c0d2241 JA |
744 | and then drop the cache. This will only work for IO engines |
745 | that are seekable, since they allow you to read the same data | |
746 | multiple times. Thus it will not work on eg network or splice | |
747 | IO. | |
afad68f7 | 748 | |
e545a6ce | 749 | unlink=bool Unlink the job files when done. Not the default, as repeated |
bf9a3edb JA |
750 | runs of that job would then waste time recreating the file |
751 | set again and again. | |
71bfa161 JA |
752 | |
753 | loops=int Run the specified number of iterations of this job. Used | |
754 | to repeat the same workload a given number of times. Defaults | |
755 | to 1. | |
756 | ||
68e1f29a | 757 | do_verify=bool Run the verify phase after a write phase. Only makes sense if |
e84c73a8 SL |
758 | verify is set. Defaults to 1. |
759 | ||
71bfa161 JA |
760 | verify=str If writing to a file, fio can verify the file contents |
761 | after each iteration of the job. The allowed values are: | |
762 | ||
763 | md5 Use an md5 sum of the data area and store | |
764 | it in the header of each block. | |
765 | ||
17dc34df JA |
766 | crc64 Use an experimental crc64 sum of the data |
767 | area and store it in the header of each | |
768 | block. | |
769 | ||
bac39e0e JA |
770 | crc32c Use a crc32c sum of the data area and store |
771 | it in the header of each block. | |
772 | ||
3845591f JA |
773 | crc32c-intel Use hardware assisted crc32c calcuation |
774 | provided on SSE4.2 enabled processors. | |
775 | ||
71bfa161 JA |
776 | crc32 Use a crc32 sum of the data area and store |
777 | it in the header of each block. | |
778 | ||
969f7ed3 JA |
779 | crc16 Use a crc16 sum of the data area and store |
780 | it in the header of each block. | |
781 | ||
17dc34df JA |
782 | crc7 Use a crc7 sum of the data area and store |
783 | it in the header of each block. | |
784 | ||
cd14cc10 JA |
785 | sha512 Use sha512 as the checksum function. |
786 | ||
787 | sha256 Use sha256 as the checksum function. | |
788 | ||
7437ee87 SL |
789 | meta Write extra information about each io |
790 | (timestamp, block number etc.). The block | |
791 | number is verified. | |
792 | ||
36690c9b JA |
793 | null Only pretend to verify. Useful for testing |
794 | internals with ioengine=null, not for much | |
795 | else. | |
796 | ||
6c219763 | 797 | This option can be used for repeated burn-in tests of a |
71bfa161 JA |
798 | system to make sure that the written data is also |
799 | correctly read back. | |
800 | ||
160b966d JA |
801 | verifysort=bool If set, fio will sort written verify blocks when it deems |
802 | it faster to read them back in a sorted manner. This is | |
803 | often the case when overwriting an existing file, since | |
804 | the blocks are already laid out in the file system. You | |
805 | can ignore this option unless doing huge amounts of really | |
806 | fast IO where the red-black tree sorting CPU time becomes | |
807 | significant. | |
3f9f4e26 | 808 | |
f7fa2653 | 809 | verify_offset=int Swap the verification header with data somewhere else |
546a9142 SL |
810 | in the block before writing. Its swapped back before |
811 | verifying. | |
812 | ||
f7fa2653 | 813 | verify_interval=int Write the verification header at a finer granularity |
3f9f4e26 SL |
814 | than the blocksize. It will be written for chunks the |
815 | size of header_interval. blocksize should divide this | |
816 | evenly. | |
90059d65 | 817 | |
e28218f3 SL |
818 | verify_pattern=int If set, fio will fill the io buffers with this |
819 | pattern. Fio defaults to filling with totally random | |
820 | bytes, but sometimes it's interesting to fill with a known | |
821 | pattern for io verification purposes. Depending on the | |
822 | width of the pattern, fio will fill 1/2/3/4 bytes of the | |
823 | buffer at the time. The verify_pattern cannot be larger than | |
824 | a 32-bit quantity. | |
825 | ||
68e1f29a | 826 | verify_fatal=bool Normally fio will keep checking the entire contents |
a12a3b4d JA |
827 | before quitting on a block verification failure. If this |
828 | option is set, fio will exit the job on the first observed | |
829 | failure. | |
160b966d | 830 | |
71bfa161 JA |
831 | stonewall Wait for preceeding jobs in the job file to exit, before |
832 | starting this one. Can be used to insert serialization | |
b3d62a75 JA |
833 | points in the job file. A stone wall also implies starting |
834 | a new reporting group. | |
835 | ||
836 | new_group Start a new reporting group. If this option isn't given, | |
837 | jobs in a file will be part of the same reporting group | |
bf9a3edb | 838 | unless separated by a stone wall (or if it's a group |
b3d62a75 | 839 | by itself, with the numjobs option). |
71bfa161 JA |
840 | |
841 | numjobs=int Create the specified number of clones of this job. May be | |
842 | used to setup a larger number of threads/processes doing | |
fa28c85a JA |
843 | the same thing. We regard that grouping of jobs as a |
844 | specific group. | |
845 | ||
846 | group_reporting If 'numjobs' is set, it may be interesting to display | |
847 | statistics for the group as a whole instead of for each | |
848 | individual job. This is especially true of 'numjobs' is | |
849 | large, looking at individual thread/process output quickly | |
850 | becomes unwieldy. If 'group_reporting' is specified, fio | |
851 | will show the final report per-group instead of per-job. | |
71bfa161 JA |
852 | |
853 | thread fio defaults to forking jobs, however if this option is | |
854 | given, fio will use pthread_create(3) to create threads | |
855 | instead. | |
856 | ||
f7fa2653 | 857 | zonesize=int Divide a file into zones of the specified size. See zoneskip. |
71bfa161 | 858 | |
f7fa2653 | 859 | zoneskip=int Skip the specified number of bytes when zonesize data has |
71bfa161 JA |
860 | been read. The two zone options can be used to only do |
861 | io on zones of a file. | |
862 | ||
076efc7c JA |
863 | write_iolog=str Write the issued io patterns to the specified file. See |
864 | read_iolog. | |
71bfa161 | 865 | |
076efc7c | 866 | read_iolog=str Open an iolog with the specified file name and replay the |
71bfa161 | 867 | io patterns it contains. This can be used to store a |
6df8adaa JA |
868 | workload and replay it sometime later. The iolog given |
869 | may also be a blktrace binary file, which allows fio | |
870 | to replay a workload captured by blktrace. See blktrace | |
871 | for how to capture such logging data. For blktrace replay, | |
872 | the file needs to be turned into a blkparse binary data | |
873 | file first (blktrace <device> -d file_for_fio.bin). | |
71bfa161 | 874 | |
e3cedca7 | 875 | write_bw_log=str If given, write a bandwidth log of the jobs in this job |
71bfa161 | 876 | file. Can be used to store data of the bandwidth of the |
e0da9bc2 JA |
877 | jobs in their lifetime. The included fio_generate_plots |
878 | script uses gnuplot to turn these text files into nice | |
e3cedca7 JA |
879 | graphs. See write_log_log for behaviour of given |
880 | filename. For this option, the postfix is _bw.log. | |
71bfa161 | 881 | |
e3cedca7 JA |
882 | write_lat_log=str Same as write_bw_log, except that this option stores io |
883 | completion latencies instead. If no filename is given | |
884 | with this option, the default filename of "jobname_type.log" | |
885 | is used. Even if the filename is given, fio will still | |
886 | append the type of log. So if one specifies | |
887 | ||
888 | write_lat_log=foo | |
889 | ||
890 | The actual log names will be foo_clat.log and foo_slat.log. | |
891 | This helps fio_generate_plot fine the logs automatically. | |
71bfa161 | 892 | |
f7fa2653 | 893 | lockmem=int Pin down the specified amount of memory with mlock(2). Can |
71bfa161 JA |
894 | potentially be used instead of removing memory or booting |
895 | with less memory to simulate a smaller amount of memory. | |
896 | ||
897 | exec_prerun=str Before running this job, issue the command specified | |
898 | through system(3). | |
899 | ||
900 | exec_postrun=str After the job completes, issue the command specified | |
901 | though system(3). | |
902 | ||
903 | ioscheduler=str Attempt to switch the device hosting the file to the specified | |
904 | io scheduler before running. | |
905 | ||
906 | cpuload=int If the job is a CPU cycle eater, attempt to use the specified | |
907 | percentage of CPU cycles. | |
908 | ||
909 | cpuchunks=int If the job is a CPU cycle eater, split the load into | |
26eca2db | 910 | cycles of the given time. In microseconds. |
71bfa161 | 911 | |
0a839f30 JA |
912 | disk_util=bool Generate disk utilization statistics, if the platform |
913 | supports it. Defaults to on. | |
914 | ||
9520ebb9 JA |
915 | disable_clat=bool Disable measurements of completion latency numbers. Useful |
916 | only for cutting back the number of calls to gettimeofday, | |
917 | as that does impact performance at really high IOPS rates. | |
918 | Note that to really get rid of a large amount of these | |
919 | calls, this option must be used with disable_slat and | |
920 | disable_bw as well. | |
921 | ||
922 | disable_slat=bool Disable measurements of submission latency numbers. See | |
923 | disable_clat. | |
924 | ||
925 | disable_bw=bool Disable measurements of throughput/bandwidth numbers. See | |
926 | disable_clat. | |
927 | ||
993bf48b JA |
928 | gtod_reduce=bool Enable all of the gettimeofday() reducing options |
929 | (disable_clat, disable_slat, disable_bw) plus reduce | |
930 | precision of the timeout somewhat to really shrink | |
931 | the gettimeofday() call count. With this option enabled, | |
932 | we only do about 0.4% of the gtod() calls we would have | |
933 | done if all time keeping was enabled. | |
934 | ||
be4ecfdf JA |
935 | gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of |
936 | execution to just getting the current time. Fio (and | |
937 | databases, for instance) are very intensive on gettimeofday() | |
938 | calls. With this option, you can set one CPU aside for | |
939 | doing nothing but logging current time to a shared memory | |
940 | location. Then the other threads/processes that run IO | |
941 | workloads need only copy that segment, instead of entering | |
942 | the kernel with a gettimeofday() call. The CPU set aside | |
943 | for doing these time calls will be excluded from other | |
944 | uses. Fio will manually clear it from the CPU mask of other | |
945 | jobs. | |
f2bba182 RR |
946 | continue_on_error=bool Normally fio will exit the job on the first observed |
947 | failure. If this option is set, fio will continue the job when | |
948 | there is a 'non-fatal error' (EIO or EILSEQ) until the runtime | |
949 | is exceeded or the I/O size specified is completed. If this | |
950 | option is used, there are two more stats that are appended, | |
951 | the total error count and the first error. The error field | |
952 | given in the stats is the first error that was hit during the | |
953 | run. | |
be4ecfdf | 954 | |
71bfa161 JA |
955 | |
956 | 6.0 Interpreting the output | |
957 | --------------------------- | |
958 | ||
959 | fio spits out a lot of output. While running, fio will display the | |
960 | status of the jobs created. An example of that would be: | |
961 | ||
73c8b082 | 962 | Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s] |
71bfa161 JA |
963 | |
964 | The characters inside the square brackets denote the current status of | |
965 | each thread. The possible values (in typical life cycle order) are: | |
966 | ||
967 | Idle Run | |
968 | ---- --- | |
969 | P Thread setup, but not started. | |
970 | C Thread created. | |
971 | I Thread initialized, waiting. | |
b0f65863 | 972 | p Thread running pre-reading file(s). |
71bfa161 JA |
973 | R Running, doing sequential reads. |
974 | r Running, doing random reads. | |
975 | W Running, doing sequential writes. | |
976 | w Running, doing random writes. | |
977 | M Running, doing mixed sequential reads/writes. | |
978 | m Running, doing mixed random reads/writes. | |
979 | F Running, currently waiting for fsync() | |
fc6bd43c | 980 | V Running, doing verification of written data. |
71bfa161 JA |
981 | E Thread exited, not reaped by main thread yet. |
982 | _ Thread reaped. | |
983 | ||
984 | The other values are fairly self explanatory - number of threads | |
c9f60304 JA |
985 | currently running and doing io, rate of io since last check (read speed |
986 | listed first, then write speed), and the estimated completion percentage | |
987 | and time for the running group. It's impossible to estimate runtime of | |
988 | the following groups (if any). | |
71bfa161 JA |
989 | |
990 | When fio is done (or interrupted by ctrl-c), it will show the data for | |
991 | each thread, group of threads, and disks in that order. For each data | |
992 | direction, the output looks like: | |
993 | ||
994 | Client1 (g=0): err= 0: | |
995 | write: io= 32MiB, bw= 666KiB/s, runt= 50320msec | |
6104ddb6 JA |
996 | slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92 |
997 | clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82 | |
998 | bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68 | |
e7823a94 | 999 | cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17 |
71619dc2 | 1000 | 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 |
1001 | submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% |
1002 | complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% | |
30061b97 | 1003 | issued r/w: total=0/32768, short=0/0 |
8abdce66 JA |
1004 | lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%, |
1005 | lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0% | |
71bfa161 JA |
1006 | |
1007 | The client number is printed, along with the group id and error of that | |
1008 | thread. Below is the io statistics, here for writes. In the order listed, | |
1009 | they denote: | |
1010 | ||
1011 | io= Number of megabytes io performed | |
1012 | bw= Average bandwidth rate | |
1013 | runt= The runtime of that thread | |
72fbda2a | 1014 | slat= Submission latency (avg being the average, stdev being the |
71bfa161 JA |
1015 | standard deviation). This is the time it took to submit |
1016 | the io. For sync io, the slat is really the completion | |
8a35c71e | 1017 | latency, since queue/complete is one operation there. This |
bf9a3edb | 1018 | value can be in milliseconds or microseconds, fio will choose |
8a35c71e | 1019 | the most appropriate base and print that. In the example |
bf9a3edb | 1020 | above, milliseconds is the best scale. |
71bfa161 JA |
1021 | clat= Completion latency. Same names as slat, this denotes the |
1022 | time from submission to completion of the io pieces. For | |
1023 | sync io, clat will usually be equal (or very close) to 0, | |
1024 | as the time from submit to complete is basically just | |
1025 | CPU time (io has already been done, see slat explanation). | |
1026 | bw= Bandwidth. Same names as the xlat stats, but also includes | |
1027 | an approximate percentage of total aggregate bandwidth | |
1028 | this thread received in this group. This last value is | |
1029 | only really useful if the threads in this group are on the | |
1030 | same disk, since they are then competing for disk access. | |
1031 | cpu= CPU usage. User and system time, along with the number | |
e7823a94 JA |
1032 | of context switches this thread went through, usage of |
1033 | system and user time, and finally the number of major | |
1034 | and minor page faults. | |
71619dc2 JA |
1035 | IO depths= The distribution of io depths over the job life time. The |
1036 | numbers are divided into powers of 2, so for example the | |
1037 | 16= entries includes depths up to that value but higher | |
1038 | than the previous entry. In other words, it covers the | |
1039 | range from 16 to 31. | |
838bc709 JA |
1040 | IO submit= How many pieces of IO were submitting in a single submit |
1041 | call. Each entry denotes that amount and below, until | |
1042 | the previous entry - eg, 8=100% mean that we submitted | |
1043 | anywhere in between 5-8 ios per submit call. | |
1044 | IO complete= Like the above submit number, but for completions instead. | |
30061b97 JA |
1045 | IO issued= The number of read/write requests issued, and how many |
1046 | of them were short. | |
ec118304 JA |
1047 | IO latencies= The distribution of IO completion latencies. This is the |
1048 | time from when IO leaves fio and when it gets completed. | |
1049 | The numbers follow the same pattern as the IO depths, | |
1050 | meaning that 2=1.6% means that 1.6% of the IO completed | |
8abdce66 JA |
1051 | within 2 msecs, 20=12.8% means that 12.8% of the IO |
1052 | took more than 10 msecs, but less than (or equal to) 20 msecs. | |
71bfa161 JA |
1053 | |
1054 | After each client has been listed, the group statistics are printed. They | |
1055 | will look like this: | |
1056 | ||
1057 | Run status group 0 (all jobs): | |
1058 | READ: io=64MiB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec | |
1059 | WRITE: io=64MiB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec | |
1060 | ||
1061 | For each data direction, it prints: | |
1062 | ||
1063 | io= Number of megabytes io performed. | |
1064 | aggrb= Aggregate bandwidth of threads in this group. | |
1065 | minb= The minimum average bandwidth a thread saw. | |
1066 | maxb= The maximum average bandwidth a thread saw. | |
1067 | mint= The smallest runtime of the threads in that group. | |
1068 | maxt= The longest runtime of the threads in that group. | |
1069 | ||
1070 | And finally, the disk statistics are printed. They will look like this: | |
1071 | ||
1072 | Disk stats (read/write): | |
1073 | sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% | |
1074 | ||
1075 | Each value is printed for both reads and writes, with reads first. The | |
1076 | numbers denote: | |
1077 | ||
1078 | ios= Number of ios performed by all groups. | |
1079 | merge= Number of merges io the io scheduler. | |
1080 | ticks= Number of ticks we kept the disk busy. | |
1081 | io_queue= Total time spent in the disk queue. | |
1082 | util= The disk utilization. A value of 100% means we kept the disk | |
1083 | busy constantly, 50% would be a disk idling half of the time. | |
1084 | ||
1085 | ||
1086 | 7.0 Terse output | |
1087 | ---------------- | |
1088 | ||
1089 | For scripted usage where you typically want to generate tables or graphs | |
6af019c9 | 1090 | of the results, fio can output the results in a semicolon separated format. |
71bfa161 JA |
1091 | The format is one long line of values, such as: |
1092 | ||
6af019c9 JA |
1093 | 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% |
1094 | ;0.0%;0.0%;0.0%;0.0%;0.0% | |
71bfa161 | 1095 | |
6820cb3b JA |
1096 | To enable terse output, use the --minimal command line option. |
1097 | ||
71bfa161 JA |
1098 | Split up, the format is as follows: |
1099 | ||
1100 | jobname, groupid, error | |
1101 | READ status: | |
1102 | KiB IO, bandwidth (KiB/sec), runtime (msec) | |
1103 | Submission latency: min, max, mean, deviation | |
1104 | Completion latency: min, max, mean, deviation | |
6c219763 | 1105 | Bw: min, max, aggregate percentage of total, mean, deviation |
71bfa161 JA |
1106 | WRITE status: |
1107 | KiB IO, bandwidth (KiB/sec), runtime (msec) | |
1108 | Submission latency: min, max, mean, deviation | |
1109 | Completion latency: min, max, mean, deviation | |
6c219763 | 1110 | Bw: min, max, aggregate percentage of total, mean, deviation |
046ee302 | 1111 | CPU usage: user, system, context switches, major faults, minor faults |
2270890c JA |
1112 | IO depths: <=1, 2, 4, 8, 16, 32, >=64 |
1113 | IO latencies: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000 | |
1114 | Text description | |
71bfa161 | 1115 |