sfree(NULL) is ok
[fio.git] / HOWTO
CommitLineData
71bfa161
JA
1Table of contents
2-----------------
3
41. Overview
52. How fio works
63. Running fio
74. Job file format
85. Detailed list of parameters
96. Normal output
107. Terse output
11
12
131.0 Overview and history
14------------------------
15fio was originally written to save me the hassle of writing special test
16case programs when I wanted to test a specific workload, either for
17performance reasons or to find/reproduce a bug. The process of writing
18such a test app can be tiresome, especially if you have to do it often.
19Hence I needed a tool that would be able to simulate a given io workload
20without resorting to writing a tailored test case again and again.
21
22A test work load is difficult to define, though. There can be any number
23of processes or threads involved, and they can each be using their own
24way of generating io. You could have someone dirtying large amounts of
25memory in an memory mapped file, or maybe several threads issuing
26reads using asynchronous io. fio needed to be flexible enough to
27simulate both of these cases, and many more.
28
292.0 How fio works
30-----------------
31The first step in getting fio to simulate a desired io workload, is
32writing a job file describing that specific setup. A job file may contain
33any number of threads and/or files - the typical contents of the job file
34is a global section defining shared parameters, and one or more job
35sections describing the jobs involved. When run, fio parses this file
36and sets everything up as described. If we break down a job from top to
37bottom, 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
65The above are the basic parameters defined for a workload, in addition
66there's a multitude of parameters that modify other aspects of how this
67job behaves.
68
69
703.0 Running fio
71---------------
72See the README file for command line parameters, there are only a few
73of them.
74
75Running 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
80and it will start doing what the job_file tells it to do. You can give
81more than one job file on the command line, fio will serialize the running
82of those files. Internally that is the same as using the 'stonewall'
83parameter described the the parameter section.
84
b4692828
JA
85If the job file contains only one job, you may as well just give the
86parameters on the command line. The command line parameters are identical
87to 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
89mirror command line option would be --iodepth 2 or --iodepth=2. You can
90also 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.
92Command line entries following a --name entry will apply to that job,
93until there are no more entries or a new --name entry is seen. This is
94similar to the job file options, where each option applies to the current
95job until a new [] job entry is seen.
b4692828 96
71bfa161
JA
97fio does not need to run as root, except if the files or devices specified
98in the job section requires that. Some other options may also be restricted,
6c219763 99such as memory locking, io scheduler switching, and decreasing the nice value.
71bfa161
JA
100
101
1024.0 Job file format
103-------------------
104As previously described, fio accepts one or more job files describing
105what it is supposed to do. The job file format is the classic ini file,
106where the names enclosed in [] brackets define the job name. You are free
107to use any ascii name you want, except 'global' which has special meaning.
108A global section sets defaults for the jobs described in that file. A job
109may override a global section parameter, and a job file may even have
110several global sections if so desired. A job is only affected by a global
65db0851
JA
111section 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 114So let's look at a really simple job file that defines two processes, each
b22989b9 115randomly reading from a 128MB file.
71bfa161
JA
116
117; -- start job file --
118[global]
119rw=randread
120size=128m
121
122[job1]
123
124[job2]
125
126; -- end job file --
127
128As you can see, the job file sections themselves are empty as all the
129described parameters are shared. As no filename= option is given, fio
c2b1e753
JA
130makes up a filename for each of the jobs as it sees fit. On the command
131line, this job would look as follows:
132
133$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
134
71bfa161 135
3c54bc46 136Let's look at an example that has a number of processes writing randomly
71bfa161
JA
137to files.
138
139; -- start job file --
140[random-writers]
141ioengine=libaio
142iodepth=4
143rw=randwrite
144bs=32k
145direct=0
146size=64m
147numjobs=4
148
149; -- end job file --
150
151Here we have no global section, as we only have one job defined anyway.
152We want to use async io here, with a depth of 4 for each file. We also
b22989b9 153increased the buffer size used to 32KB and define numjobs to 4 to
71bfa161 154fork 4 identical jobs. The result is 4 processes each randomly writing
b22989b9 155to their own 64MB file. Instead of using the above job file, you could
b4692828
JA
156have given the parameters on the command line. For this case, you would
157specify:
158
159$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
71bfa161 160
74929ac2
JA
1614.1 Environment variables
162-------------------------
163
3c54bc46
AC
164fio also supports environment variable expansion in job files. Any
165substring of the form "${VARNAME}" as part of an option value (in other
166words, on the right of the `='), will be expanded to the value of the
167environment variable called VARNAME. If no such environment variable
168is defined, or VARNAME is the empty string, the empty string will be
169substituted.
170
171As an example, let's look at a sample fio invocation and job file:
172
173$ SIZE=64m NUMJOBS=4 fio jobfile.fio
174
175; -- start job file --
176[random-writers]
177rw=randwrite
178size=${SIZE}
179numjobs=${NUMJOBS}
180; -- end job file --
181
182This will expand to the following equivalent job file at runtime:
183
184; -- start job file --
185[random-writers]
186rw=randwrite
187size=64m
188numjobs=4
189; -- end job file --
190
71bfa161
JA
191fio ships with a few example job files, you can also look there for
192inspiration.
193
74929ac2
JA
1944.2 Reserved keywords
195---------------------
196
197Additionally, fio has a set of reserved keywords that will be replaced
198internally with the appropriate value. Those keywords are:
199
200$pagesize The architecture page size of the running system
201$mb_memory Megabytes of total memory in the system
202$ncpus Number of online available CPUs
203
204These can be used on the command line or in the job file, and will be
205automatically substituted with the current system values when the job
892a6ffc
JA
206is run. Simple math is also supported on these keywords, so you can
207perform actions like:
208
209size=8*$mb_memory
210
211and get that properly expanded to 8 times the size of memory in the
212machine.
74929ac2 213
71bfa161
JA
214
2155.0 Detailed list of parameters
216-------------------------------
217
218This section describes in details each parameter associated with a job.
219Some parameters take an option of a given type, such as an integer or
220a string. The following types are used:
221
222str String. This is a sequence of alpha characters.
b09da8fa 223time Integer with possible time suffix. In seconds unless otherwise
e417fd66
JA
224 specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds,
225 minutes, and hours.
b09da8fa
JA
226int SI integer. A whole number value, which may contain a suffix
227 describing the base of the number. Accepted suffixes are k/m/g/t/p,
228 meaning kilo, mega, giga, tera, and peta. The suffix is not case
229 sensitive. So if you want to specify 4096, you could either write
230 out '4096' or just give 4k. The suffixes signify base 2 values, so
231 1024 is 1k and 1024k is 1m and so on. If the option accepts an upper
232 and lower range, use a colon ':' or minus '-' to separate such values.
233 May also include a prefix to indicate numbers base. If 0x is used,
234 the number is assumed to be hexadecimal. See irange.
71bfa161
JA
235bool Boolean. Usually parsed as an integer, however only defined for
236 true and false (1 and 0).
b09da8fa 237irange Integer range with suffix. Allows value range to be given, such
bf9a3edb 238 as 1024-4096. A colon may also be used as the separator, eg
0c9baf91
JA
239 1k:4k. If the option allows two sets of ranges, they can be
240 specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
f7fa2653 241 int.
71bfa161
JA
242
243With the above in mind, here follows the complete list of fio job
244parameters.
245
246name=str ASCII name of the job. This may be used to override the
247 name printed by fio for this job. Otherwise the job
c2b1e753 248 name is used. On the command line this parameter has the
6c219763 249 special purpose of also signaling the start of a new
c2b1e753 250 job.
71bfa161 251
61697c37
JA
252description=str Text description of the job. Doesn't do anything except
253 dump this text description when this job is run. It's
254 not parsed.
255
3776041e 256directory=str Prefix filenames with this directory. Used to place files
71bfa161
JA
257 in a different location than "./".
258
259filename=str Fio normally makes up a filename based on the job name,
260 thread number, and file number. If you want to share
261 files between threads in a job or several jobs, specify
ed92ac0c 262 a filename for each of them to override the default. If
414c2a3e
JA
263 the ioengine used is 'net', the filename is the host, port,
264 and protocol to use in the format of =host/port/protocol.
265 See ioengine=net for more. If the ioengine is file based, you
266 can specify a number of files by separating the names with a
267 ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb
268 as the two working files, you would use
8e827d35
JA
269 filename=/dev/sda:/dev/sdb. If the wanted filename does need to
270 include a colon, then escape that with a '\' character. For
271 instance, if the filename is "/dev/dsk/foo@3,0:c", then you would
272 use filename="/dev/dsk/foo@3,0\:c". '-' is a reserved name,
273 meaning stdin or stdout. Which of the two depends on the read/write
414c2a3e 274 direction set.
71bfa161 275
bbf6b540
JA
276opendir=str Tell fio to recursively add any file it can find in this
277 directory and down the file system tree.
278
3776041e 279lockfile=str Fio defaults to not locking any files before it does
4d4e80f2
JA
280 IO to them. If a file or file descriptor is shared, fio
281 can serialize IO to that file to make the end result
282 consistent. This is usual for emulating real workloads that
283 share files. The lock modes are:
284
285 none No locking. The default.
286 exclusive Only one thread/process may do IO,
287 excluding all others.
288 readwrite Read-write locking on the file. Many
289 readers may access the file at the
290 same time, but writes get exclusive
291 access.
292
293 The option may be post-fixed with a lock batch number. If
294 set, then each thread/process may do that amount of IOs to
bf9a3edb 295 the file before giving up the lock. Since lock acquisition is
4d4e80f2 296 expensive, batching the lock/unlocks will speed up IO.
29c1349f 297
d3aad8f2 298readwrite=str
71bfa161
JA
299rw=str Type of io pattern. Accepted values are:
300
301 read Sequential reads
302 write Sequential writes
303 randwrite Random writes
304 randread Random reads
305 rw Sequential mixed reads and writes
306 randrw Random mixed reads and writes
307
308 For the mixed io types, the default is to split them 50/50.
309 For certain types of io the result may still be skewed a bit,
211097b2
JA
310 since the speed may be different. It is possible to specify
311 a number of IO's to do before getting a new offset - this
312 is only useful for random IO, where fio would normally
313 generate a new random offset for every IO. If you append
314 eg 8 to randread, you would get a new random offset for
315 every 8 IO's. The result would be a seek for only every 8
316 IO's, instead of for every IO. Use rw=randread:8 to specify
317 that.
71bfa161 318
90fef2d1
JA
319kb_base=int The base unit for a kilobyte. The defacto base is 2^10, 1024.
320 Storage manufacturers like to use 10^3 or 1000 as a base
321 ten unit instead, for obvious reasons. Allow values are
322 1024 or 1000, with 1024 being the default.
323
ee738499
JA
324randrepeat=bool For random IO workloads, seed the generator in a predictable
325 way so that results are repeatable across repetitions.
326
7bc8c2cf
JA
327fallocate=bool By default, fio will use fallocate() to advise the system
328 of the size of the file we are going to write. This can be
329 turned off with fallocate=0. May not be available on all
330 supported platforms.
331
d2f3ac35
JA
332fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
333 on what IO patterns it is likely to issue. Sometimes you
334 want to test specific IO patterns without telling the
335 kernel about it, in which case you can disable this option.
336 If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
337 IO and POSIX_FADV_RANDOM for random IO.
338
f7fa2653 339size=int The total size of file io for this job. Fio will run until
7616cafe
JA
340 this many bytes has been transferred, unless runtime is
341 limited by other options (such as 'runtime', for instance).
3776041e 342 Unless specific nrfiles and filesize options are given,
7616cafe
JA
343 fio will divide this size between the available files
344 specified by the job.
71bfa161 345
f7fa2653 346filesize=int Individual file sizes. May be a range, in which case fio
9c60ce64
JA
347 will select sizes for files at random within the given range
348 and limited to 'size' in total (if that is given). If not
349 given, each created file is the same size.
350
aa31f1f1
SL
351fill_device=bool Sets size to something really large and waits for ENOSPC (no
352 space left on device) as the terminating condition. Only makes
3ce9dcaf
JA
353 sense with sequential write. For a read workload, the mount
354 point will be filled first then IO started on the result.
aa31f1f1 355
f7fa2653
JA
356blocksize=int
357bs=int The block size used for the io units. Defaults to 4k. Values
358 can be given for both read and writes. If a single int is
359 given, it will apply to both. If a second int is specified
f90eff5a
JA
360 after a comma, it will apply to writes only. In other words,
361 the format is either bs=read_and_write or bs=read,write.
362 bs=4k,8k will thus use 4k blocks for reads, and 8k blocks
787f7e95
JA
363 for writes. If you only wish to set the write size, you
364 can do so by passing an empty read size - bs=,8k will set
365 8k for writes and leave the read default value.
a00735e6 366
2b7a01d0
JA
367blockalign=int
368ba=int At what boundary to align random IO offsets. Defaults to
369 the same as 'blocksize' the minimum blocksize given.
370 Minimum alignment is typically 512b for using direct IO,
371 though it usually depends on the hardware block size. This
372 option is mutually exclusive with using a random map for
373 files, so it will turn off that option.
374
d3aad8f2 375blocksize_range=irange
71bfa161
JA
376bsrange=irange Instead of giving a single block size, specify a range
377 and fio will mix the issued io block sizes. The issued
378 io unit will always be a multiple of the minimum value
f90eff5a
JA
379 given (also see bs_unaligned). Applies to both reads and
380 writes, however a second range can be given after a comma.
381 See bs=.
a00735e6 382
564ca972
JA
383bssplit=str Sometimes you want even finer grained control of the
384 block sizes issued, not just an even split between them.
385 This option allows you to weight various block sizes,
386 so that you are able to define a specific amount of
387 block sizes issued. The format for this option is:
388
389 bssplit=blocksize/percentage:blocksize/percentage
390
391 for as many block sizes as needed. So if you want to define
392 a workload that has 50% 64k blocks, 10% 4k blocks, and
393 40% 32k blocks, you would write:
394
395 bssplit=4k/10:64k/50:32k/40
396
397 Ordering does not matter. If the percentage is left blank,
398 fio will fill in the remaining values evenly. So a bssplit
399 option like this one:
400
401 bssplit=4k/50:1k/:32k/
402
403 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages
404 always add up to 100, if bssplit is given a range that adds
405 up to more, it will error out.
406
720e84ad
JA
407 bssplit also supports giving separate splits to reads and
408 writes. The format is identical to what bs= accepts. You
409 have to separate the read and write parts with a comma. So
410 if you want a workload that has 50% 2k reads and 50% 4k reads,
411 while having 90% 4k writes and 10% 8k writes, you would
412 specify:
413
414 bssplit=2k/50:4k/50,4k/90,8k/10
415
d3aad8f2 416blocksize_unaligned
690adba3
JA
417bs_unaligned If this option is given, any byte size value within bsrange
418 may be used as a block range. This typically wont work with
419 direct IO, as that normally requires sector alignment.
71bfa161 420
e9459e5a
JA
421zero_buffers If this option is given, fio will init the IO buffers to
422 all zeroes. The default is to fill them with random data.
423
5973cafb
JA
424refill_buffers If this option is given, fio will refill the IO buffers
425 on every submit. The default is to only fill it at init
426 time and reuse that data. Only makes sense if zero_buffers
41ccd845
JA
427 isn't specified, naturally. If data verification is enabled,
428 refill_buffers is also automatically enabled.
5973cafb 429
71bfa161
JA
430nrfiles=int Number of files to use for this job. Defaults to 1.
431
390b1537
JA
432openfiles=int Number of files to keep open at the same time. Defaults to
433 the same as nrfiles, can be set smaller to limit the number
434 simultaneous opens.
435
5af1c6f3
JA
436file_service_type=str Defines how fio decides which file from a job to
437 service next. The following types are defined:
438
439 random Just choose a file at random.
440
441 roundrobin Round robin over open files. This
442 is the default.
443
a086c257
JA
444 sequential Finish one file before moving on to
445 the next. Multiple files can still be
446 open depending on 'openfiles'.
447
1907dbc6
JA
448 The string can have a number appended, indicating how
449 often to switch to a new file. So if option random:4 is
450 given, fio will switch to a new random file after 4 ios
451 have been issued.
452
71bfa161
JA
453ioengine=str Defines how the job issues io to the file. The following
454 types are defined:
455
456 sync Basic read(2) or write(2) io. lseek(2) is
457 used to position the io location.
458
a31041ea 459 psync Basic pread(2) or pwrite(2) io.
460
e05af9e5 461 vsync Basic readv(2) or writev(2) IO.
1d2af02a 462
15d182aa
JA
463 libaio Linux native asynchronous io. Note that Linux
464 may only support queued behaviour with
465 non-buffered IO (set direct=1 or buffered=0).
71bfa161
JA
466
467 posixaio glibc posix asynchronous io.
468
417f0068
JA
469 solarisaio Solaris native asynchronous io.
470
71bfa161
JA
471 mmap File is memory mapped and data copied
472 to/from using memcpy(3).
473
474 splice splice(2) is used to transfer the data and
475 vmsplice(2) to transfer data from user
476 space to the kernel.
477
d0ff85df
JA
478 syslet-rw Use the syslet system calls to make
479 regular read/write async.
480
71bfa161 481 sg SCSI generic sg v3 io. May either be
6c219763 482 synchronous using the SG_IO ioctl, or if
71bfa161
JA
483 the target is an sg character device
484 we use read(2) and write(2) for asynchronous
485 io.
486
a94ea28b
JA
487 null Doesn't transfer any data, just pretends
488 to. This is mainly used to exercise fio
489 itself and for debugging/testing purposes.
490
ed92ac0c
JA
491 net Transfer over the network to given host:port.
492 'filename' must be set appropriately to
414c2a3e 493 filename=host/port/protocol regardless of send
ed92ac0c 494 or receive, if the latter only the port
414c2a3e
JA
495 argument is used. 'host' may be an IP address
496 or hostname, port is the port number to be used,
497 and protocol may be 'udp' or 'tcp'. If no
498 protocol is given, TCP is used.
ed92ac0c 499
9cce02e8
JA
500 netsplice Like net, but uses splice/vmsplice to
501 map data and send/receive.
502
53aec0a4 503 cpuio Doesn't transfer any data, but burns CPU
ba0fbe10
JA
504 cycles according to the cpuload= and
505 cpucycle= options. Setting cpuload=85
506 will cause that job to do nothing but burn
36ecec83
GP
507 85% of the CPU. In case of SMP machines,
508 use numjobs=<no_of_cpu> to get desired CPU
509 usage, as the cpuload only loads a single
510 CPU at the desired rate.
ba0fbe10 511
e9a1806f
JA
512 guasi The GUASI IO engine is the Generic Userspace
513 Asyncronous Syscall Interface approach
514 to async IO. See
515
516 http://www.xmailserver.org/guasi-lib.html
517
518 for more info on GUASI.
519
8a7bd877
JA
520 external Prefix to specify loading an external
521 IO engine object file. Append the engine
522 filename, eg ioengine=external:/tmp/foo.o
523 to load ioengine foo.o in /tmp.
524
71bfa161
JA
525iodepth=int This defines how many io units to keep in flight against
526 the file. The default is 1 for each file defined in this
527 job, can be overridden with a larger value for higher
528 concurrency.
529
4950421a 530iodepth_batch_submit=int
cb5ab512 531iodepth_batch=int This defines how many pieces of IO to submit at once.
89e820f6
JA
532 It defaults to 1 which means that we submit each IO
533 as soon as it is available, but can be raised to submit
534 bigger batches of IO at the time.
cb5ab512 535
4950421a
JA
536iodepth_batch_complete=int This defines how many pieces of IO to retrieve
537 at once. It defaults to 1 which means that we'll ask
538 for a minimum of 1 IO in the retrieval process from
539 the kernel. The IO retrieval will go on until we
540 hit the limit set by iodepth_low. If this variable is
541 set to 0, then fio will always check for completed
542 events before queuing more IO. This helps reduce
543 IO latency, at the cost of more retrieval system calls.
544
e916b390
JA
545iodepth_low=int The low water mark indicating when to start filling
546 the queue again. Defaults to the same as iodepth, meaning
547 that fio will attempt to keep the queue full at all times.
548 If iodepth is set to eg 16 and iodepth_low is set to 4, then
549 after fio has filled the queue of 16 requests, it will let
550 the depth drain down to 4 before starting to fill it again.
551
71bfa161 552direct=bool If value is true, use non-buffered io. This is usually
76a43db4
JA
553 O_DIRECT.
554
555buffered=bool If value is true, use buffered io. This is the opposite
556 of the 'direct' option. Defaults to true.
71bfa161 557
f7fa2653 558offset=int Start io at the given offset in the file. The data before
71bfa161
JA
559 the given offset will not be touched. This effectively
560 caps the file size at real_size - offset.
561
562fsync=int If writing to a file, issue a sync of the dirty data
563 for every number of blocks given. For example, if you give
564 32 as a parameter, fio will sync the file for every 32
565 writes issued. If fio is using non-buffered io, we may
566 not sync the file. The exception is the sg io engine, which
6c219763 567 synchronizes the disk cache anyway.
71bfa161 568
e76b1da4 569fdatasync=int Like fsync= but uses fdatasync() to only sync data and not
5f9099ea 570 metadata blocks.
e72fa4d4
JA
571 In FreeBSD there is no fdatasync(), this falls back to
572 using fsync()
5f9099ea 573
e76b1da4
JA
574sync_file_range=str:val Use sync_file_range() for every 'val' number of
575 write operations. Fio will track range of writes that
576 have happened since the last sync_file_range() call. 'str'
577 can currently be one or more of:
578
579 wait_before SYNC_FILE_RANGE_WAIT_BEFORE
580 write SYNC_FILE_RANGE_WRITE
581 wait_after SYNC_FILE_RANGE_WAIT_AFTER
582
583 So if you do sync_file_range=wait_before,write:8, fio would
584 use SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE for
585 every 8 writes. Also see the sync_file_range(2) man page.
586 This option is Linux specific.
587
5036fc1e
JA
588overwrite=bool If true, writes to a file will always overwrite existing
589 data. If the file doesn't already exist, it will be
590 created before the write phase begins. If the file exists
591 and is large enough for the specified write phase, nothing
592 will be done.
71bfa161
JA
593
594end_fsync=bool If true, fsync file contents when the job exits.
595
ebb1415f
JA
596fsync_on_close=bool If true, fio will fsync() a dirty file on close.
597 This differs from end_fsync in that it will happen on every
598 file close, not just at the end of the job.
599
71bfa161
JA
600rwmixread=int How large a percentage of the mix should be reads.
601
602rwmixwrite=int How large a percentage of the mix should be writes. If both
603 rwmixread and rwmixwrite is given and the values do not add
604 up to 100%, the latter of the two will be used to override
c35dd7a6
JA
605 the first. This may interfere with a given rate setting,
606 if fio is asked to limit reads or writes to a certain rate.
607 If that is the case, then the distribution may be skewed.
71bfa161 608
bb8895e0
JA
609norandommap Normally fio will cover every block of the file when doing
610 random IO. If this option is given, fio will just get a
611 new random offset without looking at past io history. This
612 means that some blocks may not be read or written, and that
613 some blocks may be read/written more than once. This option
8347239a
JA
614 is mutually exclusive with verify= if and only if multiple
615 blocksizes (via bsrange=) are used, since fio only tracks
616 complete rewrites of blocks.
bb8895e0 617
2b386d25
JA
618softrandommap See norandommap. If fio runs with the random block map enabled
619 and it fails to allocate the map, if this option is set it
620 will continue without a random block map. As coverage will
621 not be as complete as with random maps, this option is
622 disabled by default.
623
71bfa161
JA
624nice=int Run the job with the given nice value. See man nice(2).
625
626prio=int Set the io priority value of this job. Linux limits us to
627 a positive value between 0 and 7, with 0 being the highest.
628 See man ionice(1).
629
630prioclass=int Set the io priority class. See man ionice(1).
631
632thinktime=int Stall the job x microseconds after an io has completed before
633 issuing the next. May be used to simulate processing being
48097d5c
JA
634 done by an application. See thinktime_blocks and
635 thinktime_spin.
636
637thinktime_spin=int
638 Only valid if thinktime is set - pretend to spend CPU time
639 doing something with the data received, before falling back
640 to sleeping for the rest of the period specified by
641 thinktime.
9c1f7434
JA
642
643thinktime_blocks
644 Only valid if thinktime is set - control how many blocks
645 to issue, before waiting 'thinktime' usecs. If not set,
646 defaults to 1 which will make fio wait 'thinktime' usecs
647 after every block.
71bfa161 648
581e7141 649rate=int Cap the bandwidth used by this job. The number is in bytes/sec,
b09da8fa 650 the normal suffix rules apply. You can use rate=500k to limit
581e7141
JA
651 reads and writes to 500k each, or you can specify read and
652 writes separately. Using rate=1m,500k would limit reads to
653 1MB/sec and writes to 500KB/sec. Capping only reads or
654 writes can be done with rate=,500k or rate=500k,. The former
655 will only limit writes (to 500KB/sec), the latter will only
656 limit reads.
71bfa161
JA
657
658ratemin=int Tell fio to do whatever it can to maintain at least this
4e991c23 659 bandwidth. Failing to meet this requirement, will cause
581e7141
JA
660 the job to exit. The same format as rate is used for
661 read vs write separation.
4e991c23
JA
662
663rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same
664 as rate, just specified independently of bandwidth. If the
665 job is given a block size range instead of a fixed value,
581e7141
JA
666 the smallest block size is used as the metric. The same format
667 as rate is used for read vs write seperation.
4e991c23
JA
668
669rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
581e7141
JA
670 the job to exit. The same format as rate is used for read vs
671 write seperation.
71bfa161
JA
672
673ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number
6c219763 674 of milliseconds.
71bfa161
JA
675
676cpumask=int Set the CPU affinity of this job. The parameter given is a
a08bc17f
JA
677 bitmask of allowed CPU's the job may run on. So if you want
678 the allowed CPUs to be 1 and 5, you would pass the decimal
679 value of (1 << 1 | 1 << 5), or 34. See man
7dbb6eba 680 sched_setaffinity(2). This may not work on all supported
b0ea08ce
JA
681 operating systems or kernel versions. This option doesn't
682 work well for a higher CPU count than what you can store in
683 an integer mask, so it can only control cpus 1-32. For
684 boxes with larger CPU counts, use cpus_allowed.
71bfa161 685
d2e268b0
JA
686cpus_allowed=str Controls the same options as cpumask, but it allows a text
687 setting of the permitted CPUs instead. So to use CPUs 1 and
62a7273d
JA
688 5, you would specify cpus_allowed=1,5. This options also
689 allows a range of CPUs. Say you wanted a binding to CPUs
690 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15.
d2e268b0 691
e417fd66 692startdelay=time Start this job the specified number of seconds after fio
71bfa161
JA
693 has started. Only useful if the job file contains several
694 jobs, and you want to delay starting some jobs to a certain
695 time.
696
e417fd66 697runtime=time Tell fio to terminate processing after the specified number
71bfa161
JA
698 of seconds. It can be quite hard to determine for how long
699 a specified job will run, so this parameter is handy to
700 cap the total runtime to a given time.
701
cf4464ca 702time_based If set, fio will run for the duration of the runtime
bf9a3edb 703 specified even if the file(s) are completely read or
cf4464ca
JA
704 written. It will simply loop over the same workload
705 as many times as the runtime allows.
706
e417fd66 707ramp_time=time If set, fio will run the specified workload for this amount
721938ae
JA
708 of time before logging any performance numbers. Useful for
709 letting performance settle before logging results, thus
b29ee5b3
JA
710 minimizing the runtime required for stable results. Note
711 that the ramp_time is considered lead in time for a job,
712 thus it will increase the total runtime if a special timeout
713 or runtime is specified.
721938ae 714
71bfa161
JA
715invalidate=bool Invalidate the buffer/page cache parts for this file prior
716 to starting io. Defaults to true.
717
718sync=bool Use sync io for buffered writes. For the majority of the
719 io engines, this means using O_SYNC.
720
d3aad8f2 721iomem=str
71bfa161
JA
722mem=str Fio can use various types of memory as the io unit buffer.
723 The allowed values are:
724
725 malloc Use memory from malloc(3) as the buffers.
726
727 shm Use shared memory as the buffers. Allocated
728 through shmget(2).
729
74b025b0
JA
730 shmhuge Same as shm, but use huge pages as backing.
731
313cb206
JA
732 mmap Use mmap to allocate buffers. May either be
733 anonymous memory, or can be file backed if
734 a filename is given after the option. The
735 format is mem=mmap:/path/to/file.
71bfa161 736
d0bdaf49
JA
737 mmaphuge Use a memory mapped huge file as the buffer
738 backing. Append filename after mmaphuge, ala
739 mem=mmaphuge:/hugetlbfs/file
740
71bfa161 741 The area allocated is a function of the maximum allowed
5394ae5f
JA
742 bs size for the job, multiplied by the io depth given. Note
743 that for shmhuge and mmaphuge to work, the system must have
744 free huge pages allocated. This can normally be checked
745 and set by reading/writing /proc/sys/vm/nr_hugepages on a
b22989b9 746 Linux system. Fio assumes a huge page is 4MB in size. So
5394ae5f
JA
747 to calculate the number of huge pages you need for a given
748 job file, add up the io depth of all jobs (normally one unless
749 iodepth= is used) and multiply by the maximum bs set. Then
750 divide that number by the huge page size. You can see the
751 size of the huge pages in /proc/meminfo. If no huge pages
752 are allocated by having a non-zero number in nr_hugepages,
56bb17f2 753 using mmaphuge or shmhuge will fail. Also see hugepage-size.
5394ae5f
JA
754
755 mmaphuge also needs to have hugetlbfs mounted and the file
756 location should point there. So if it's mounted in /huge,
757 you would use mem=mmaphuge:/huge/somefile.
71bfa161 758
d529ee19
JA
759iomem_align=int This indiciates the memory alignment of the IO memory buffers.
760 Note that the given alignment is applied to the first IO unit
761 buffer, if using iodepth the alignment of the following buffers
762 are given by the bs used. In other words, if using a bs that is
763 a multiple of the page sized in the system, all buffers will
764 be aligned to this value. If using a bs that is not page
765 aligned, the alignment of subsequent IO memory buffers is the
766 sum of the iomem_align and bs used.
767
f7fa2653 768hugepage-size=int
56bb17f2 769 Defines the size of a huge page. Must at least be equal
b22989b9 770 to the system setting, see /proc/meminfo. Defaults to 4MB.
c51074e7
JA
771 Should probably always be a multiple of megabytes, so using
772 hugepage-size=Xm is the preferred way to set this to avoid
773 setting a non-pow-2 bad value.
56bb17f2 774
71bfa161
JA
775exitall When one job finishes, terminate the rest. The default is
776 to wait for each job to finish, sometimes that is not the
777 desired action.
778
779bwavgtime=int Average the calculated bandwidth over the given time. Value
6c219763 780 is specified in milliseconds.
71bfa161
JA
781
782create_serialize=bool If true, serialize the file creating for the jobs.
783 This may be handy to avoid interleaving of data
784 files, which may greatly depend on the filesystem
785 used and even the number of processors in the system.
786
787create_fsync=bool fsync the data file after creation. This is the
788 default.
789
814452bd
JA
790create_on_open=bool Don't pre-setup the files for IO, just create open()
791 when it's time to do IO to that file.
792
afad68f7 793pre_read=bool If this is given, files will be pre-read into memory before
34f1c044
JA
794 starting the given IO operation. This will also clear
795 the 'invalidate' flag, since it is pointless to pre-read
9c0d2241
JA
796 and then drop the cache. This will only work for IO engines
797 that are seekable, since they allow you to read the same data
798 multiple times. Thus it will not work on eg network or splice
799 IO.
afad68f7 800
e545a6ce 801unlink=bool Unlink the job files when done. Not the default, as repeated
bf9a3edb
JA
802 runs of that job would then waste time recreating the file
803 set again and again.
71bfa161
JA
804
805loops=int Run the specified number of iterations of this job. Used
806 to repeat the same workload a given number of times. Defaults
807 to 1.
808
68e1f29a 809do_verify=bool Run the verify phase after a write phase. Only makes sense if
e84c73a8
SL
810 verify is set. Defaults to 1.
811
71bfa161
JA
812verify=str If writing to a file, fio can verify the file contents
813 after each iteration of the job. The allowed values are:
814
815 md5 Use an md5 sum of the data area and store
816 it in the header of each block.
817
17dc34df
JA
818 crc64 Use an experimental crc64 sum of the data
819 area and store it in the header of each
820 block.
821
bac39e0e
JA
822 crc32c Use a crc32c sum of the data area and store
823 it in the header of each block.
824
3845591f
JA
825 crc32c-intel Use hardware assisted crc32c calcuation
826 provided on SSE4.2 enabled processors.
827
71bfa161
JA
828 crc32 Use a crc32 sum of the data area and store
829 it in the header of each block.
830
969f7ed3
JA
831 crc16 Use a crc16 sum of the data area and store
832 it in the header of each block.
833
17dc34df
JA
834 crc7 Use a crc7 sum of the data area and store
835 it in the header of each block.
836
cd14cc10
JA
837 sha512 Use sha512 as the checksum function.
838
839 sha256 Use sha256 as the checksum function.
840
7c353ceb
JA
841 sha1 Use optimized sha1 as the checksum function.
842
7437ee87
SL
843 meta Write extra information about each io
844 (timestamp, block number etc.). The block
845 number is verified.
846
36690c9b
JA
847 null Only pretend to verify. Useful for testing
848 internals with ioengine=null, not for much
849 else.
850
6c219763 851 This option can be used for repeated burn-in tests of a
71bfa161 852 system to make sure that the written data is also
b892dc08
JA
853 correctly read back. If the data direction given is
854 a read or random read, fio will assume that it should
855 verify a previously written file. If the data direction
856 includes any form of write, the verify will be of the
857 newly written data.
71bfa161 858
160b966d
JA
859verifysort=bool If set, fio will sort written verify blocks when it deems
860 it faster to read them back in a sorted manner. This is
861 often the case when overwriting an existing file, since
862 the blocks are already laid out in the file system. You
863 can ignore this option unless doing huge amounts of really
864 fast IO where the red-black tree sorting CPU time becomes
865 significant.
3f9f4e26 866
f7fa2653 867verify_offset=int Swap the verification header with data somewhere else
546a9142
SL
868 in the block before writing. Its swapped back before
869 verifying.
870
f7fa2653 871verify_interval=int Write the verification header at a finer granularity
3f9f4e26
SL
872 than the blocksize. It will be written for chunks the
873 size of header_interval. blocksize should divide this
874 evenly.
90059d65 875
0e92f873 876verify_pattern=str If set, fio will fill the io buffers with this
e28218f3
SL
877 pattern. Fio defaults to filling with totally random
878 bytes, but sometimes it's interesting to fill with a known
879 pattern for io verification purposes. Depending on the
880 width of the pattern, fio will fill 1/2/3/4 bytes of the
0e92f873
RR
881 buffer at the time(it can be either a decimal or a hex number).
882 The verify_pattern if larger than a 32-bit quantity has to
883 be a hex number that starts with either "0x" or "0X".
e28218f3 884
68e1f29a 885verify_fatal=bool Normally fio will keep checking the entire contents
a12a3b4d
JA
886 before quitting on a block verification failure. If this
887 option is set, fio will exit the job on the first observed
888 failure.
e8462bd8
JA
889
890verify_async=int Fio will normally verify IO inline from the submitting
891 thread. This option takes an integer describing how many
892 async offload threads to create for IO verification instead,
893 causing fio to offload the duty of verifying IO contents
c85c324c
JA
894 to one or more separate threads. If using this offload
895 option, even sync IO engines can benefit from using an
896 iodepth setting higher than 1, as it allows them to have
897 IO in flight while verifies are running.
e8462bd8
JA
898
899verify_async_cpus=str Tell fio to set the given CPU affinity on the
900 async IO verification threads. See cpus_allowed for the
901 format used.
160b966d 902
71bfa161
JA
903stonewall Wait for preceeding jobs in the job file to exit, before
904 starting this one. Can be used to insert serialization
b3d62a75
JA
905 points in the job file. A stone wall also implies starting
906 a new reporting group.
907
908new_group Start a new reporting group. If this option isn't given,
909 jobs in a file will be part of the same reporting group
bf9a3edb 910 unless separated by a stone wall (or if it's a group
b3d62a75 911 by itself, with the numjobs option).
71bfa161
JA
912
913numjobs=int Create the specified number of clones of this job. May be
914 used to setup a larger number of threads/processes doing
fa28c85a
JA
915 the same thing. We regard that grouping of jobs as a
916 specific group.
917
918group_reporting If 'numjobs' is set, it may be interesting to display
919 statistics for the group as a whole instead of for each
920 individual job. This is especially true of 'numjobs' is
921 large, looking at individual thread/process output quickly
922 becomes unwieldy. If 'group_reporting' is specified, fio
923 will show the final report per-group instead of per-job.
71bfa161
JA
924
925thread fio defaults to forking jobs, however if this option is
926 given, fio will use pthread_create(3) to create threads
927 instead.
928
f7fa2653 929zonesize=int Divide a file into zones of the specified size. See zoneskip.
71bfa161 930
f7fa2653 931zoneskip=int Skip the specified number of bytes when zonesize data has
71bfa161
JA
932 been read. The two zone options can be used to only do
933 io on zones of a file.
934
076efc7c
JA
935write_iolog=str Write the issued io patterns to the specified file. See
936 read_iolog.
71bfa161 937
076efc7c 938read_iolog=str Open an iolog with the specified file name and replay the
71bfa161 939 io patterns it contains. This can be used to store a
6df8adaa
JA
940 workload and replay it sometime later. The iolog given
941 may also be a blktrace binary file, which allows fio
942 to replay a workload captured by blktrace. See blktrace
943 for how to capture such logging data. For blktrace replay,
944 the file needs to be turned into a blkparse binary data
945 file first (blktrace <device> -d file_for_fio.bin).
71bfa161 946
e3cedca7 947write_bw_log=str If given, write a bandwidth log of the jobs in this job
71bfa161 948 file. Can be used to store data of the bandwidth of the
e0da9bc2
JA
949 jobs in their lifetime. The included fio_generate_plots
950 script uses gnuplot to turn these text files into nice
e3cedca7
JA
951 graphs. See write_log_log for behaviour of given
952 filename. For this option, the postfix is _bw.log.
71bfa161 953
e3cedca7
JA
954write_lat_log=str Same as write_bw_log, except that this option stores io
955 completion latencies instead. If no filename is given
956 with this option, the default filename of "jobname_type.log"
957 is used. Even if the filename is given, fio will still
958 append the type of log. So if one specifies
959
960 write_lat_log=foo
961
962 The actual log names will be foo_clat.log and foo_slat.log.
963 This helps fio_generate_plot fine the logs automatically.
71bfa161 964
f7fa2653 965lockmem=int Pin down the specified amount of memory with mlock(2). Can
71bfa161
JA
966 potentially be used instead of removing memory or booting
967 with less memory to simulate a smaller amount of memory.
968
969exec_prerun=str Before running this job, issue the command specified
970 through system(3).
971
972exec_postrun=str After the job completes, issue the command specified
973 though system(3).
974
975ioscheduler=str Attempt to switch the device hosting the file to the specified
976 io scheduler before running.
977
978cpuload=int If the job is a CPU cycle eater, attempt to use the specified
979 percentage of CPU cycles.
980
981cpuchunks=int If the job is a CPU cycle eater, split the load into
26eca2db 982 cycles of the given time. In microseconds.
71bfa161 983
0a839f30
JA
984disk_util=bool Generate disk utilization statistics, if the platform
985 supports it. Defaults to on.
986
9520ebb9
JA
987disable_clat=bool Disable measurements of completion latency numbers. Useful
988 only for cutting back the number of calls to gettimeofday,
989 as that does impact performance at really high IOPS rates.
990 Note that to really get rid of a large amount of these
991 calls, this option must be used with disable_slat and
992 disable_bw as well.
993
994disable_slat=bool Disable measurements of submission latency numbers. See
995 disable_clat.
996
997disable_bw=bool Disable measurements of throughput/bandwidth numbers. See
998 disable_clat.
999
993bf48b
JA
1000gtod_reduce=bool Enable all of the gettimeofday() reducing options
1001 (disable_clat, disable_slat, disable_bw) plus reduce
1002 precision of the timeout somewhat to really shrink
1003 the gettimeofday() call count. With this option enabled,
1004 we only do about 0.4% of the gtod() calls we would have
1005 done if all time keeping was enabled.
1006
be4ecfdf
JA
1007gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of
1008 execution to just getting the current time. Fio (and
1009 databases, for instance) are very intensive on gettimeofday()
1010 calls. With this option, you can set one CPU aside for
1011 doing nothing but logging current time to a shared memory
1012 location. Then the other threads/processes that run IO
1013 workloads need only copy that segment, instead of entering
1014 the kernel with a gettimeofday() call. The CPU set aside
1015 for doing these time calls will be excluded from other
1016 uses. Fio will manually clear it from the CPU mask of other
1017 jobs.
a696fa2a 1018
f2bba182
RR
1019continue_on_error=bool Normally fio will exit the job on the first observed
1020 failure. If this option is set, fio will continue the job when
1021 there is a 'non-fatal error' (EIO or EILSEQ) until the runtime
1022 is exceeded or the I/O size specified is completed. If this
1023 option is used, there are two more stats that are appended,
1024 the total error count and the first error. The error field
1025 given in the stats is the first error that was hit during the
1026 run.
be4ecfdf 1027
6adb38a1
JA
1028cgroup=str Add job to this control group. If it doesn't exist, it will
1029 be created. The system must have a mounted cgroup blkio
1030 mount point for this to work. If your system doesn't have it
1031 mounted, you can do so with:
a696fa2a
JA
1032
1033 # mount -t cgroup -o blkio none /cgroup
1034
a696fa2a
JA
1035cgroup_weight=int Set the weight of the cgroup to this value. See
1036 the documentation that comes with the kernel, allowed values
1037 are in the range of 100..1000.
71bfa161 1038
e0b0d892
JA
1039uid=int Instead of running as the invoking user, set the user ID to
1040 this value before the thread/process does any work.
1041
1042gid=int Set group ID, see uid.
1043
71bfa161
JA
10446.0 Interpreting the output
1045---------------------------
1046
1047fio spits out a lot of output. While running, fio will display the
1048status of the jobs created. An example of that would be:
1049
73c8b082 1050Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
71bfa161
JA
1051
1052The characters inside the square brackets denote the current status of
1053each thread. The possible values (in typical life cycle order) are:
1054
1055Idle Run
1056---- ---
1057P Thread setup, but not started.
1058C Thread created.
1059I Thread initialized, waiting.
b0f65863 1060 p Thread running pre-reading file(s).
71bfa161
JA
1061 R Running, doing sequential reads.
1062 r Running, doing random reads.
1063 W Running, doing sequential writes.
1064 w Running, doing random writes.
1065 M Running, doing mixed sequential reads/writes.
1066 m Running, doing mixed random reads/writes.
1067 F Running, currently waiting for fsync()
fc6bd43c 1068 V Running, doing verification of written data.
71bfa161
JA
1069E Thread exited, not reaped by main thread yet.
1070_ Thread reaped.
1071
1072The other values are fairly self explanatory - number of threads
c9f60304
JA
1073currently running and doing io, rate of io since last check (read speed
1074listed first, then write speed), and the estimated completion percentage
1075and time for the running group. It's impossible to estimate runtime of
1076the following groups (if any).
71bfa161
JA
1077
1078When fio is done (or interrupted by ctrl-c), it will show the data for
1079each thread, group of threads, and disks in that order. For each data
1080direction, the output looks like:
1081
1082Client1 (g=0): err= 0:
b22989b9 1083 write: io= 32MB, bw= 666KB/s, runt= 50320msec
6104ddb6
JA
1084 slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92
1085 clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82
b22989b9 1086 bw (KB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68
e7823a94 1087 cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17
71619dc2 1088 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
1089 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
1090 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
30061b97 1091 issued r/w: total=0/32768, short=0/0
8abdce66
JA
1092 lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%,
1093 lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0%
71bfa161
JA
1094
1095The client number is printed, along with the group id and error of that
1096thread. Below is the io statistics, here for writes. In the order listed,
1097they denote:
1098
1099io= Number of megabytes io performed
1100bw= Average bandwidth rate
1101runt= The runtime of that thread
72fbda2a 1102 slat= Submission latency (avg being the average, stdev being the
71bfa161
JA
1103 standard deviation). This is the time it took to submit
1104 the io. For sync io, the slat is really the completion
8a35c71e 1105 latency, since queue/complete is one operation there. This
bf9a3edb 1106 value can be in milliseconds or microseconds, fio will choose
8a35c71e 1107 the most appropriate base and print that. In the example
bf9a3edb 1108 above, milliseconds is the best scale.
71bfa161
JA
1109 clat= Completion latency. Same names as slat, this denotes the
1110 time from submission to completion of the io pieces. For
1111 sync io, clat will usually be equal (or very close) to 0,
1112 as the time from submit to complete is basically just
1113 CPU time (io has already been done, see slat explanation).
1114 bw= Bandwidth. Same names as the xlat stats, but also includes
1115 an approximate percentage of total aggregate bandwidth
1116 this thread received in this group. This last value is
1117 only really useful if the threads in this group are on the
1118 same disk, since they are then competing for disk access.
1119cpu= CPU usage. User and system time, along with the number
e7823a94
JA
1120 of context switches this thread went through, usage of
1121 system and user time, and finally the number of major
1122 and minor page faults.
71619dc2
JA
1123IO depths= The distribution of io depths over the job life time. The
1124 numbers are divided into powers of 2, so for example the
1125 16= entries includes depths up to that value but higher
1126 than the previous entry. In other words, it covers the
1127 range from 16 to 31.
838bc709
JA
1128IO submit= How many pieces of IO were submitting in a single submit
1129 call. Each entry denotes that amount and below, until
1130 the previous entry - eg, 8=100% mean that we submitted
1131 anywhere in between 5-8 ios per submit call.
1132IO complete= Like the above submit number, but for completions instead.
30061b97
JA
1133IO issued= The number of read/write requests issued, and how many
1134 of them were short.
ec118304
JA
1135IO latencies= The distribution of IO completion latencies. This is the
1136 time from when IO leaves fio and when it gets completed.
1137 The numbers follow the same pattern as the IO depths,
1138 meaning that 2=1.6% means that 1.6% of the IO completed
8abdce66
JA
1139 within 2 msecs, 20=12.8% means that 12.8% of the IO
1140 took more than 10 msecs, but less than (or equal to) 20 msecs.
71bfa161
JA
1141
1142After each client has been listed, the group statistics are printed. They
1143will look like this:
1144
1145Run status group 0 (all jobs):
b22989b9
JA
1146 READ: io=64MB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec
1147 WRITE: io=64MB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec
71bfa161
JA
1148
1149For each data direction, it prints:
1150
1151io= Number of megabytes io performed.
1152aggrb= Aggregate bandwidth of threads in this group.
1153minb= The minimum average bandwidth a thread saw.
1154maxb= The maximum average bandwidth a thread saw.
1155mint= The smallest runtime of the threads in that group.
1156maxt= The longest runtime of the threads in that group.
1157
1158And finally, the disk statistics are printed. They will look like this:
1159
1160Disk stats (read/write):
1161 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
1162
1163Each value is printed for both reads and writes, with reads first. The
1164numbers denote:
1165
1166ios= Number of ios performed by all groups.
1167merge= Number of merges io the io scheduler.
1168ticks= Number of ticks we kept the disk busy.
1169io_queue= Total time spent in the disk queue.
1170util= The disk utilization. A value of 100% means we kept the disk
1171 busy constantly, 50% would be a disk idling half of the time.
1172
1173
11747.0 Terse output
1175----------------
1176
1177For scripted usage where you typically want to generate tables or graphs
6af019c9 1178of the results, fio can output the results in a semicolon separated format.
71bfa161
JA
1179The format is one long line of values, such as:
1180
6af019c9
JA
1181client1;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%
1182;0.0%;0.0%;0.0%;0.0%;0.0%
71bfa161 1183
6820cb3b
JA
1184To enable terse output, use the --minimal command line option.
1185
71bfa161
JA
1186Split up, the format is as follows:
1187
1188 jobname, groupid, error
1189 READ status:
b22989b9 1190 KB IO, bandwidth (KB/sec), runtime (msec)
71bfa161
JA
1191 Submission latency: min, max, mean, deviation
1192 Completion latency: min, max, mean, deviation
6c219763 1193 Bw: min, max, aggregate percentage of total, mean, deviation
71bfa161 1194 WRITE status:
b22989b9 1195 KB IO, bandwidth (KB/sec), runtime (msec)
71bfa161
JA
1196 Submission latency: min, max, mean, deviation
1197 Completion latency: min, max, mean, deviation
6c219763 1198 Bw: min, max, aggregate percentage of total, mean, deviation
046ee302 1199 CPU usage: user, system, context switches, major faults, minor faults
2270890c
JA
1200 IO depths: <=1, 2, 4, 8, 16, 32, >=64
1201 IO latencies: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000
1202 Text description
71bfa161 1203