8 5. Detailed list of parameters
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.
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.
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:
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.
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
48 IO size How much data are we going to be reading/writing.
50 IO engine How do we issue io? We could be memory mapping the
51 file, we could be using regular read/write, we
52 could be using splice, async io, syslet, or even
55 IO depth If the io engine is async, how large a queuing
56 depth do we want to maintain?
58 IO type Should we be doing buffered io, or direct/raw io?
60 Num files How many files are we spreading the workload over.
62 Num threads How many threads or processes should we spread
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
72 See the README file for command line parameters, there are only a few
75 Running fio is normally the easiest part - you just give it the job file
76 (or job files) as parameters:
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.
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
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.
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,
99 such as memory locking, io scheduler switching, and decreasing the nice value.
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
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.
114 So let's look at a really simple job file that defines two processes, each
115 randomly reading from a 128MB file.
117 ; -- start job file --
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
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:
133 $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
136 Let's look at an example that has a number of processes writing randomly
139 ; -- start job file --
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 32KB and define numjobs to 4 to
154 fork 4 identical jobs. The result is 4 processes each randomly writing
155 to their own 64MB file. Instead of using the above job file, you could
156 have given the parameters on the command line. For this case, you would
159 $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
161 4.1 Environment variables
162 -------------------------
164 fio also supports environment variable expansion in job files. Any
165 substring of the form "${VARNAME}" as part of an option value (in other
166 words, on the right of the `='), will be expanded to the value of the
167 environment variable called VARNAME. If no such environment variable
168 is defined, or VARNAME is the empty string, the empty string will be
171 As an example, let's look at a sample fio invocation and job file:
173 $ SIZE=64m NUMJOBS=4 fio jobfile.fio
175 ; -- start job file --
182 This will expand to the following equivalent job file at runtime:
184 ; -- start job file --
191 fio ships with a few example job files, you can also look there for
194 4.2 Reserved keywords
195 ---------------------
197 Additionally, fio has a set of reserved keywords that will be replaced
198 internally with the appropriate value. Those keywords are:
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
204 These can be used on the command line or in the job file, and will be
205 automatically substituted with the current system values when the job
206 is run. Simple math is also supported on these keywords, so you can
207 perform actions like:
211 and get that properly expanded to 8 times the size of memory in the
215 5.0 Detailed list of parameters
216 -------------------------------
218 This section describes in details each parameter associated with a job.
219 Some parameters take an option of a given type, such as an integer or
220 a string. The following types are used:
222 str String. This is a sequence of alpha characters.
223 time Integer with possible time suffix. In seconds unless otherwise
224 specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds,
226 int 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, and you may also include trailing 'b' (eg 'kb' is the same
230 as 'k'). So if you want to specify 4096, you could either write
231 out '4096' or just give 4k. The suffixes signify base 2 values, so
232 1024 is 1k and 1024k is 1m and so on, unless the suffix is explicitly
233 set to a base 10 value using 'kib', 'mib', 'gib', etc. If that is the
234 case, then 1000 is used as the multiplier. This can be handy for
235 disks, since manufacturers generally use base 10 values when listing
236 the capacity of a drive. If the option accepts an upper and lower
237 range, use a colon ':' or minus '-' to separate such values. May also
238 include a prefix to indicate numbers base. If 0x is used, the number
239 is assumed to be hexadecimal. See irange.
240 bool Boolean. Usually parsed as an integer, however only defined for
241 true and false (1 and 0).
242 irange Integer range with suffix. Allows value range to be given, such
243 as 1024-4096. A colon may also be used as the separator, eg
244 1k:4k. If the option allows two sets of ranges, they can be
245 specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
247 float_list A list of floating numbers, separated by a ':' character.
249 With the above in mind, here follows the complete list of fio job
252 name=str ASCII name of the job. This may be used to override the
253 name printed by fio for this job. Otherwise the job
254 name is used. On the command line this parameter has the
255 special purpose of also signaling the start of a new
258 description=str Text description of the job. Doesn't do anything except
259 dump this text description when this job is run. It's
262 directory=str Prefix filenames with this directory. Used to place files
263 in a different location than "./".
265 filename=str Fio normally makes up a filename based on the job name,
266 thread number, and file number. If you want to share
267 files between threads in a job or several jobs, specify
268 a filename for each of them to override the default. If
269 the ioengine used is 'net', the filename is the host, port,
270 and protocol to use in the format of =host/port/protocol.
271 See ioengine=net for more. If the ioengine is file based, you
272 can specify a number of files by separating the names with a
273 ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb
274 as the two working files, you would use
275 filename=/dev/sda:/dev/sdb. On Windows, disk devices are accessed
276 as \\.\PhysicalDrive0 for the first device, \\.\PhysicalDrive1
277 for the second etc. If the wanted filename does need to
278 include a colon, then escape that with a '\' character.
279 For instance, if the filename is "/dev/dsk/foo@3,0:c",
280 then you would use filename="/dev/dsk/foo@3,0\:c".
281 '-' is a reserved name, meaning stdin or stdout. Which of the
282 two depends on the read/write direction set.
284 opendir=str Tell fio to recursively add any file it can find in this
285 directory and down the file system tree.
287 lockfile=str Fio defaults to not locking any files before it does
288 IO to them. If a file or file descriptor is shared, fio
289 can serialize IO to that file to make the end result
290 consistent. This is usual for emulating real workloads that
291 share files. The lock modes are:
293 none No locking. The default.
294 exclusive Only one thread/process may do IO,
295 excluding all others.
296 readwrite Read-write locking on the file. Many
297 readers may access the file at the
298 same time, but writes get exclusive
301 The option may be post-fixed with a lock batch number. If
302 set, then each thread/process may do that amount of IOs to
303 the file before giving up the lock. Since lock acquisition is
304 expensive, batching the lock/unlocks will speed up IO.
307 rw=str Type of io pattern. Accepted values are:
309 read Sequential reads
310 write Sequential writes
311 randwrite Random writes
312 randread Random reads
313 rw Sequential mixed reads and writes
314 randrw Random mixed reads and writes
316 For the mixed io types, the default is to split them 50/50.
317 For certain types of io the result may still be skewed a bit,
318 since the speed may be different. It is possible to specify
319 a number of IO's to do before getting a new offset, this is
320 one by appending a ':<nr>' to the end of the string given.
321 For a random read, it would look like 'rw=randread:8' for
322 passing in an offset modifier with a value of 8. See the
323 'rw_sequencer' option.
325 rw_sequencer=str If an offset modifier is given by appending a number to
326 the rw=<str> line, then this option controls how that
327 number modifies the IO offset being generated. Accepted
330 sequential Generate sequential offset
331 identical Generate the same offset
333 'sequential' is only useful for random IO, where fio would
334 normally generate a new random offset for every IO. If you
335 append eg 8 to randread, you would get a new random offset for
336 every 8 IO's. The result would be a seek for only every 8
337 IO's, instead of for every IO. Use rw=randread:8 to specify
338 that. As sequential IO is already sequential, setting
339 'sequential' for that would not result in any differences.
340 'identical' behaves in a similar fashion, except it sends
341 the same offset 8 number of times before generating a new
344 kb_base=int The base unit for a kilobyte. The defacto base is 2^10, 1024.
345 Storage manufacturers like to use 10^3 or 1000 as a base
346 ten unit instead, for obvious reasons. Allow values are
347 1024 or 1000, with 1024 being the default.
349 randrepeat=bool For random IO workloads, seed the generator in a predictable
350 way so that results are repeatable across repetitions.
352 use_os_rand=bool Fio can either use the random generator supplied by the OS
353 to generator random offsets, or it can use it's own internal
354 generator (based on Tausworthe). Default is to use the
355 internal generator, which is often of better quality and
358 fallocate=str Whether pre-allocation is performed when laying down files.
361 none Do not pre-allocate space
362 posix Pre-allocate via posix_fallocate()
363 keep Pre-allocate via fallocate() with
364 FALLOC_FL_KEEP_SIZE set
365 0 Backward-compatible alias for 'none'
366 1 Backward-compatible alias for 'posix'
368 May not be available on all supported platforms. 'keep' is only
369 available on Linux.If using ZFS on Solaris this must be set to
370 'none' because ZFS doesn't support it. Default: 'posix'.
372 fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
373 on what IO patterns it is likely to issue. Sometimes you
374 want to test specific IO patterns without telling the
375 kernel about it, in which case you can disable this option.
376 If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
377 IO and POSIX_FADV_RANDOM for random IO.
379 size=int The total size of file io for this job. Fio will run until
380 this many bytes has been transferred, unless runtime is
381 limited by other options (such as 'runtime', for instance).
382 Unless specific nrfiles and filesize options are given,
383 fio will divide this size between the available files
384 specified by the job. If not set, fio will use the full
385 size of the given files or devices. If the the files
386 do not exist, size must be given. It is also possible to
387 give size as a percentage between 1 and 100. If size=20%
388 is given, fio will use 20% of the full size of the given
391 filesize=int Individual file sizes. May be a range, in which case fio
392 will select sizes for files at random within the given range
393 and limited to 'size' in total (if that is given). If not
394 given, each created file is the same size.
397 fill_fs=bool Sets size to something really large and waits for ENOSPC (no
398 space left on device) as the terminating condition. Only makes
399 sense with sequential write. For a read workload, the mount
400 point will be filled first then IO started on the result. This
401 option doesn't make sense if operating on a raw device node,
402 since the size of that is already known by the file system.
403 Additionally, writing beyond end-of-device will not return
407 bs=int The block size used for the io units. Defaults to 4k. Values
408 can be given for both read and writes. If a single int is
409 given, it will apply to both. If a second int is specified
410 after a comma, it will apply to writes only. In other words,
411 the format is either bs=read_and_write or bs=read,write.
412 bs=4k,8k will thus use 4k blocks for reads, and 8k blocks
413 for writes. If you only wish to set the write size, you
414 can do so by passing an empty read size - bs=,8k will set
415 8k for writes and leave the read default value.
418 ba=int At what boundary to align random IO offsets. Defaults to
419 the same as 'blocksize' the minimum blocksize given.
420 Minimum alignment is typically 512b for using direct IO,
421 though it usually depends on the hardware block size. This
422 option is mutually exclusive with using a random map for
423 files, so it will turn off that option.
425 blocksize_range=irange
426 bsrange=irange Instead of giving a single block size, specify a range
427 and fio will mix the issued io block sizes. The issued
428 io unit will always be a multiple of the minimum value
429 given (also see bs_unaligned). Applies to both reads and
430 writes, however a second range can be given after a comma.
433 bssplit=str Sometimes you want even finer grained control of the
434 block sizes issued, not just an even split between them.
435 This option allows you to weight various block sizes,
436 so that you are able to define a specific amount of
437 block sizes issued. The format for this option is:
439 bssplit=blocksize/percentage:blocksize/percentage
441 for as many block sizes as needed. So if you want to define
442 a workload that has 50% 64k blocks, 10% 4k blocks, and
443 40% 32k blocks, you would write:
445 bssplit=4k/10:64k/50:32k/40
447 Ordering does not matter. If the percentage is left blank,
448 fio will fill in the remaining values evenly. So a bssplit
449 option like this one:
451 bssplit=4k/50:1k/:32k/
453 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages
454 always add up to 100, if bssplit is given a range that adds
455 up to more, it will error out.
457 bssplit also supports giving separate splits to reads and
458 writes. The format is identical to what bs= accepts. You
459 have to separate the read and write parts with a comma. So
460 if you want a workload that has 50% 2k reads and 50% 4k reads,
461 while having 90% 4k writes and 10% 8k writes, you would
464 bssplit=2k/50:4k/50,4k/90,8k/10
467 bs_unaligned If this option is given, any byte size value within bsrange
468 may be used as a block range. This typically wont work with
469 direct IO, as that normally requires sector alignment.
471 zero_buffers If this option is given, fio will init the IO buffers to
472 all zeroes. The default is to fill them with random data.
474 refill_buffers If this option is given, fio will refill the IO buffers
475 on every submit. The default is to only fill it at init
476 time and reuse that data. Only makes sense if zero_buffers
477 isn't specified, naturally. If data verification is enabled,
478 refill_buffers is also automatically enabled.
480 nrfiles=int Number of files to use for this job. Defaults to 1.
482 openfiles=int Number of files to keep open at the same time. Defaults to
483 the same as nrfiles, can be set smaller to limit the number
486 file_service_type=str Defines how fio decides which file from a job to
487 service next. The following types are defined:
489 random Just choose a file at random.
491 roundrobin Round robin over open files. This
494 sequential Finish one file before moving on to
495 the next. Multiple files can still be
496 open depending on 'openfiles'.
498 The string can have a number appended, indicating how
499 often to switch to a new file. So if option random:4 is
500 given, fio will switch to a new random file after 4 ios
503 ioengine=str Defines how the job issues io to the file. The following
506 sync Basic read(2) or write(2) io. lseek(2) is
507 used to position the io location.
509 psync Basic pread(2) or pwrite(2) io.
511 vsync Basic readv(2) or writev(2) IO.
513 libaio Linux native asynchronous io. Note that Linux
514 may only support queued behaviour with
515 non-buffered IO (set direct=1 or buffered=0).
517 posixaio glibc posix asynchronous io.
519 solarisaio Solaris native asynchronous io.
521 windowsaio Windows native asynchronous io.
523 mmap File is memory mapped and data copied
524 to/from using memcpy(3).
526 splice splice(2) is used to transfer the data and
527 vmsplice(2) to transfer data from user
530 syslet-rw Use the syslet system calls to make
531 regular read/write async.
533 sg SCSI generic sg v3 io. May either be
534 synchronous using the SG_IO ioctl, or if
535 the target is an sg character device
536 we use read(2) and write(2) for asynchronous
539 null Doesn't transfer any data, just pretends
540 to. This is mainly used to exercise fio
541 itself and for debugging/testing purposes.
543 net Transfer over the network to given host:port.
544 'filename' must be set appropriately to
545 filename=host/port/protocol regardless of send
546 or receive, if the latter only the port
547 argument is used. 'host' may be an IP address
548 or hostname, port is the port number to be used,
549 and protocol may be 'udp' or 'tcp'. If no
550 protocol is given, TCP is used.
552 netsplice Like net, but uses splice/vmsplice to
553 map data and send/receive.
555 cpuio Doesn't transfer any data, but burns CPU
556 cycles according to the cpuload= and
557 cpucycle= options. Setting cpuload=85
558 will cause that job to do nothing but burn
559 85% of the CPU. In case of SMP machines,
560 use numjobs=<no_of_cpu> to get desired CPU
561 usage, as the cpuload only loads a single
562 CPU at the desired rate.
564 guasi The GUASI IO engine is the Generic Userspace
565 Asyncronous Syscall Interface approach
568 http://www.xmailserver.org/guasi-lib.html
570 for more info on GUASI.
572 rdma The RDMA I/O engine supports both RDMA
573 memory semantics (RDMA_WRITE/RDMA_READ) and
574 channel semantics (Send/Recv) for the
575 InfiniBand, RoCE and iWARP protocols.
577 external Prefix to specify loading an external
578 IO engine object file. Append the engine
579 filename, eg ioengine=external:/tmp/foo.o
580 to load ioengine foo.o in /tmp.
582 iodepth=int This defines how many io units to keep in flight against
583 the file. The default is 1 for each file defined in this
584 job, can be overridden with a larger value for higher
585 concurrency. Note that increasing iodepth beyond 1 will not
586 affect synchronous ioengines (except for small degress when
587 verify_async is in use). Even async engines may impose OS
588 restrictions causing the desired depth not to be achieved.
589 This may happen on Linux when using libaio and not setting
590 direct=1, since buffered IO is not async on that OS. Keep an
591 eye on the IO depth distribution in the fio output to verify
592 that the achieved depth is as expected. Default: 1.
594 iodepth_batch_submit=int
595 iodepth_batch=int This defines how many pieces of IO to submit at once.
596 It defaults to 1 which means that we submit each IO
597 as soon as it is available, but can be raised to submit
598 bigger batches of IO at the time.
600 iodepth_batch_complete=int This defines how many pieces of IO to retrieve
601 at once. It defaults to 1 which means that we'll ask
602 for a minimum of 1 IO in the retrieval process from
603 the kernel. The IO retrieval will go on until we
604 hit the limit set by iodepth_low. If this variable is
605 set to 0, then fio will always check for completed
606 events before queuing more IO. This helps reduce
607 IO latency, at the cost of more retrieval system calls.
609 iodepth_low=int The low water mark indicating when to start filling
610 the queue again. Defaults to the same as iodepth, meaning
611 that fio will attempt to keep the queue full at all times.
612 If iodepth is set to eg 16 and iodepth_low is set to 4, then
613 after fio has filled the queue of 16 requests, it will let
614 the depth drain down to 4 before starting to fill it again.
616 direct=bool If value is true, use non-buffered io. This is usually
617 O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
619 buffered=bool If value is true, use buffered io. This is the opposite
620 of the 'direct' option. Defaults to true.
622 offset=int Start io at the given offset in the file. The data before
623 the given offset will not be touched. This effectively
624 caps the file size at real_size - offset.
626 fsync=int If writing to a file, issue a sync of the dirty data
627 for every number of blocks given. For example, if you give
628 32 as a parameter, fio will sync the file for every 32
629 writes issued. If fio is using non-buffered io, we may
630 not sync the file. The exception is the sg io engine, which
631 synchronizes the disk cache anyway.
633 fdatasync=int Like fsync= but uses fdatasync() to only sync data and not
635 In FreeBSD there is no fdatasync(), this falls back to
638 sync_file_range=str:val Use sync_file_range() for every 'val' number of
639 write operations. Fio will track range of writes that
640 have happened since the last sync_file_range() call. 'str'
641 can currently be one or more of:
643 wait_before SYNC_FILE_RANGE_WAIT_BEFORE
644 write SYNC_FILE_RANGE_WRITE
645 wait_after SYNC_FILE_RANGE_WAIT_AFTER
647 So if you do sync_file_range=wait_before,write:8, fio would
648 use SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE for
649 every 8 writes. Also see the sync_file_range(2) man page.
650 This option is Linux specific.
652 overwrite=bool If true, writes to a file will always overwrite existing
653 data. If the file doesn't already exist, it will be
654 created before the write phase begins. If the file exists
655 and is large enough for the specified write phase, nothing
658 end_fsync=bool If true, fsync file contents when the job exits.
660 fsync_on_close=bool If true, fio will fsync() a dirty file on close.
661 This differs from end_fsync in that it will happen on every
662 file close, not just at the end of the job.
664 rwmixread=int How large a percentage of the mix should be reads.
666 rwmixwrite=int How large a percentage of the mix should be writes. If both
667 rwmixread and rwmixwrite is given and the values do not add
668 up to 100%, the latter of the two will be used to override
669 the first. This may interfere with a given rate setting,
670 if fio is asked to limit reads or writes to a certain rate.
671 If that is the case, then the distribution may be skewed.
673 norandommap Normally fio will cover every block of the file when doing
674 random IO. If this option is given, fio will just get a
675 new random offset without looking at past io history. This
676 means that some blocks may not be read or written, and that
677 some blocks may be read/written more than once. This option
678 is mutually exclusive with verify= if and only if multiple
679 blocksizes (via bsrange=) are used, since fio only tracks
680 complete rewrites of blocks.
682 softrandommap=bool See norandommap. If fio runs with the random block map
683 enabled and it fails to allocate the map, if this option is
684 set it will continue without a random block map. As coverage
685 will not be as complete as with random maps, this option is
688 nice=int Run the job with the given nice value. See man nice(2).
690 prio=int Set the io priority value of this job. Linux limits us to
691 a positive value between 0 and 7, with 0 being the highest.
694 prioclass=int Set the io priority class. See man ionice(1).
696 thinktime=int Stall the job x microseconds after an io has completed before
697 issuing the next. May be used to simulate processing being
698 done by an application. See thinktime_blocks and
702 Only valid if thinktime is set - pretend to spend CPU time
703 doing something with the data received, before falling back
704 to sleeping for the rest of the period specified by
708 Only valid if thinktime is set - control how many blocks
709 to issue, before waiting 'thinktime' usecs. If not set,
710 defaults to 1 which will make fio wait 'thinktime' usecs
713 rate=int Cap the bandwidth used by this job. The number is in bytes/sec,
714 the normal suffix rules apply. You can use rate=500k to limit
715 reads and writes to 500k each, or you can specify read and
716 writes separately. Using rate=1m,500k would limit reads to
717 1MB/sec and writes to 500KB/sec. Capping only reads or
718 writes can be done with rate=,500k or rate=500k,. The former
719 will only limit writes (to 500KB/sec), the latter will only
722 ratemin=int Tell fio to do whatever it can to maintain at least this
723 bandwidth. Failing to meet this requirement, will cause
724 the job to exit. The same format as rate is used for
725 read vs write separation.
727 rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same
728 as rate, just specified independently of bandwidth. If the
729 job is given a block size range instead of a fixed value,
730 the smallest block size is used as the metric. The same format
731 as rate is used for read vs write seperation.
733 rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
734 the job to exit. The same format as rate is used for read vs
737 ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number
740 cpumask=int Set the CPU affinity of this job. The parameter given is a
741 bitmask of allowed CPU's the job may run on. So if you want
742 the allowed CPUs to be 1 and 5, you would pass the decimal
743 value of (1 << 1 | 1 << 5), or 34. See man
744 sched_setaffinity(2). This may not work on all supported
745 operating systems or kernel versions. This option doesn't
746 work well for a higher CPU count than what you can store in
747 an integer mask, so it can only control cpus 1-32. For
748 boxes with larger CPU counts, use cpus_allowed.
750 cpus_allowed=str Controls the same options as cpumask, but it allows a text
751 setting of the permitted CPUs instead. So to use CPUs 1 and
752 5, you would specify cpus_allowed=1,5. This options also
753 allows a range of CPUs. Say you wanted a binding to CPUs
754 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15.
756 startdelay=time Start this job the specified number of seconds after fio
757 has started. Only useful if the job file contains several
758 jobs, and you want to delay starting some jobs to a certain
761 runtime=time Tell fio to terminate processing after the specified number
762 of seconds. It can be quite hard to determine for how long
763 a specified job will run, so this parameter is handy to
764 cap the total runtime to a given time.
766 time_based If set, fio will run for the duration of the runtime
767 specified even if the file(s) are completely read or
768 written. It will simply loop over the same workload
769 as many times as the runtime allows.
771 ramp_time=time If set, fio will run the specified workload for this amount
772 of time before logging any performance numbers. Useful for
773 letting performance settle before logging results, thus
774 minimizing the runtime required for stable results. Note
775 that the ramp_time is considered lead in time for a job,
776 thus it will increase the total runtime if a special timeout
777 or runtime is specified.
779 invalidate=bool Invalidate the buffer/page cache parts for this file prior
780 to starting io. Defaults to true.
782 sync=bool Use sync io for buffered writes. For the majority of the
783 io engines, this means using O_SYNC.
786 mem=str Fio can use various types of memory as the io unit buffer.
787 The allowed values are:
789 malloc Use memory from malloc(3) as the buffers.
791 shm Use shared memory as the buffers. Allocated
794 shmhuge Same as shm, but use huge pages as backing.
796 mmap Use mmap to allocate buffers. May either be
797 anonymous memory, or can be file backed if
798 a filename is given after the option. The
799 format is mem=mmap:/path/to/file.
801 mmaphuge Use a memory mapped huge file as the buffer
802 backing. Append filename after mmaphuge, ala
803 mem=mmaphuge:/hugetlbfs/file
805 The area allocated is a function of the maximum allowed
806 bs size for the job, multiplied by the io depth given. Note
807 that for shmhuge and mmaphuge to work, the system must have
808 free huge pages allocated. This can normally be checked
809 and set by reading/writing /proc/sys/vm/nr_hugepages on a
810 Linux system. Fio assumes a huge page is 4MB in size. So
811 to calculate the number of huge pages you need for a given
812 job file, add up the io depth of all jobs (normally one unless
813 iodepth= is used) and multiply by the maximum bs set. Then
814 divide that number by the huge page size. You can see the
815 size of the huge pages in /proc/meminfo. If no huge pages
816 are allocated by having a non-zero number in nr_hugepages,
817 using mmaphuge or shmhuge will fail. Also see hugepage-size.
819 mmaphuge also needs to have hugetlbfs mounted and the file
820 location should point there. So if it's mounted in /huge,
821 you would use mem=mmaphuge:/huge/somefile.
823 iomem_align=int This indiciates the memory alignment of the IO memory buffers.
824 Note that the given alignment is applied to the first IO unit
825 buffer, if using iodepth the alignment of the following buffers
826 are given by the bs used. In other words, if using a bs that is
827 a multiple of the page sized in the system, all buffers will
828 be aligned to this value. If using a bs that is not page
829 aligned, the alignment of subsequent IO memory buffers is the
830 sum of the iomem_align and bs used.
833 Defines the size of a huge page. Must at least be equal
834 to the system setting, see /proc/meminfo. Defaults to 4MB.
835 Should probably always be a multiple of megabytes, so using
836 hugepage-size=Xm is the preferred way to set this to avoid
837 setting a non-pow-2 bad value.
839 exitall When one job finishes, terminate the rest. The default is
840 to wait for each job to finish, sometimes that is not the
843 bwavgtime=int Average the calculated bandwidth over the given time. Value
844 is specified in milliseconds.
846 create_serialize=bool If true, serialize the file creating for the jobs.
847 This may be handy to avoid interleaving of data
848 files, which may greatly depend on the filesystem
849 used and even the number of processors in the system.
851 create_fsync=bool fsync the data file after creation. This is the
854 create_on_open=bool Don't pre-setup the files for IO, just create open()
855 when it's time to do IO to that file.
857 pre_read=bool If this is given, files will be pre-read into memory before
858 starting the given IO operation. This will also clear
859 the 'invalidate' flag, since it is pointless to pre-read
860 and then drop the cache. This will only work for IO engines
861 that are seekable, since they allow you to read the same data
862 multiple times. Thus it will not work on eg network or splice
865 unlink=bool Unlink the job files when done. Not the default, as repeated
866 runs of that job would then waste time recreating the file
869 loops=int Run the specified number of iterations of this job. Used
870 to repeat the same workload a given number of times. Defaults
873 do_verify=bool Run the verify phase after a write phase. Only makes sense if
874 verify is set. Defaults to 1.
876 verify=str If writing to a file, fio can verify the file contents
877 after each iteration of the job. The allowed values are:
879 md5 Use an md5 sum of the data area and store
880 it in the header of each block.
882 crc64 Use an experimental crc64 sum of the data
883 area and store it in the header of each
886 crc32c Use a crc32c sum of the data area and store
887 it in the header of each block.
889 crc32c-intel Use hardware assisted crc32c calcuation
890 provided on SSE4.2 enabled processors. Falls
891 back to regular software crc32c, if not
892 supported by the system.
894 crc32 Use a crc32 sum of the data area and store
895 it in the header of each block.
897 crc16 Use a crc16 sum of the data area and store
898 it in the header of each block.
900 crc7 Use a crc7 sum of the data area and store
901 it in the header of each block.
903 sha512 Use sha512 as the checksum function.
905 sha256 Use sha256 as the checksum function.
907 sha1 Use optimized sha1 as the checksum function.
909 meta Write extra information about each io
910 (timestamp, block number etc.). The block
911 number is verified. See also verify_pattern.
913 null Only pretend to verify. Useful for testing
914 internals with ioengine=null, not for much
917 This option can be used for repeated burn-in tests of a
918 system to make sure that the written data is also
919 correctly read back. If the data direction given is
920 a read or random read, fio will assume that it should
921 verify a previously written file. If the data direction
922 includes any form of write, the verify will be of the
925 verifysort=bool If set, fio will sort written verify blocks when it deems
926 it faster to read them back in a sorted manner. This is
927 often the case when overwriting an existing file, since
928 the blocks are already laid out in the file system. You
929 can ignore this option unless doing huge amounts of really
930 fast IO where the red-black tree sorting CPU time becomes
933 verify_offset=int Swap the verification header with data somewhere else
934 in the block before writing. Its swapped back before
937 verify_interval=int Write the verification header at a finer granularity
938 than the blocksize. It will be written for chunks the
939 size of header_interval. blocksize should divide this
942 verify_pattern=str If set, fio will fill the io buffers with this
943 pattern. Fio defaults to filling with totally random
944 bytes, but sometimes it's interesting to fill with a known
945 pattern for io verification purposes. Depending on the
946 width of the pattern, fio will fill 1/2/3/4 bytes of the
947 buffer at the time(it can be either a decimal or a hex number).
948 The verify_pattern if larger than a 32-bit quantity has to
949 be a hex number that starts with either "0x" or "0X". Use
952 verify_fatal=bool Normally fio will keep checking the entire contents
953 before quitting on a block verification failure. If this
954 option is set, fio will exit the job on the first observed
957 verify_dump=bool If set, dump the contents of both the original data
958 block and the data block we read off disk to files. This
959 allows later analysis to inspect just what kind of data
960 corruption occurred. On by default.
962 verify_async=int Fio will normally verify IO inline from the submitting
963 thread. This option takes an integer describing how many
964 async offload threads to create for IO verification instead,
965 causing fio to offload the duty of verifying IO contents
966 to one or more separate threads. If using this offload
967 option, even sync IO engines can benefit from using an
968 iodepth setting higher than 1, as it allows them to have
969 IO in flight while verifies are running.
971 verify_async_cpus=str Tell fio to set the given CPU affinity on the
972 async IO verification threads. See cpus_allowed for the
975 verify_backlog=int Fio will normally verify the written contents of a
976 job that utilizes verify once that job has completed. In
977 other words, everything is written then everything is read
978 back and verified. You may want to verify continually
979 instead for a variety of reasons. Fio stores the meta data
980 associated with an IO block in memory, so for large
981 verify workloads, quite a bit of memory would be used up
982 holding this meta data. If this option is enabled, fio
983 will write only N blocks before verifying these blocks.
985 will verify the previously written blocks before continuing
988 verify_backlog_batch=int Control how many blocks fio will verify
989 if verify_backlog is set. If not set, will default to
990 the value of verify_backlog (meaning the entire queue
991 is read back and verified). If verify_backlog_batch is
992 less than verify_backlog then not all blocks will be verified,
993 if verify_backlog_batch is larger than verify_backlog, some
994 blocks will be verified more than once.
997 wait_for_previous Wait for preceeding jobs in the job file to exit, before
998 starting this one. Can be used to insert serialization
999 points in the job file. A stone wall also implies starting
1000 a new reporting group.
1002 new_group Start a new reporting group. If this option isn't given,
1003 jobs in a file will be part of the same reporting group
1004 unless separated by a stone wall (or if it's a group
1005 by itself, with the numjobs option).
1007 numjobs=int Create the specified number of clones of this job. May be
1008 used to setup a larger number of threads/processes doing
1009 the same thing. We regard that grouping of jobs as a
1012 group_reporting If 'numjobs' is set, it may be interesting to display
1013 statistics for the group as a whole instead of for each
1014 individual job. This is especially true of 'numjobs' is
1015 large, looking at individual thread/process output quickly
1016 becomes unwieldy. If 'group_reporting' is specified, fio
1017 will show the final report per-group instead of per-job.
1019 thread fio defaults to forking jobs, however if this option is
1020 given, fio will use pthread_create(3) to create threads
1023 zonesize=int Divide a file into zones of the specified size. See zoneskip.
1025 zoneskip=int Skip the specified number of bytes when zonesize data has
1026 been read. The two zone options can be used to only do
1027 io on zones of a file.
1029 write_iolog=str Write the issued io patterns to the specified file. See
1030 read_iolog. Specify a separate file for each job, otherwise
1031 the iologs will be interspersed and the file may be corrupt.
1033 read_iolog=str Open an iolog with the specified file name and replay the
1034 io patterns it contains. This can be used to store a
1035 workload and replay it sometime later. The iolog given
1036 may also be a blktrace binary file, which allows fio
1037 to replay a workload captured by blktrace. See blktrace
1038 for how to capture such logging data. For blktrace replay,
1039 the file needs to be turned into a blkparse binary data
1040 file first (blkparse <device> -o /dev/null -d file_for_fio.bin).
1042 replay_no_stall=int When replaying I/O with read_iolog the default behavior
1043 is to attempt to respect the time stamps within the log and
1044 replay them with the appropriate delay between IOPS. By
1045 setting this variable fio will not respect the timestamps and
1046 attempt to replay them as fast as possible while still
1047 respecting ordering. The result is the same I/O pattern to a
1048 given device, but different timings.
1050 replay_redirect=str While replaying I/O patterns using read_iolog the
1051 default behavior is to replay the IOPS onto the major/minor
1052 device that each IOP was recorded from. This is sometimes
1053 undesireable because on a different machine those major/minor
1054 numbers can map to a different device. Changing hardware on
1055 the same system can also result in a different major/minor
1056 mapping. Replay_redirect causes all IOPS to be replayed onto
1057 the single specified device regardless of the device it was
1058 recorded from. i.e. replay_redirect=/dev/sdc would cause all
1059 IO in the blktrace to be replayed onto /dev/sdc. This means
1060 multiple devices will be replayed onto a single, if the trace
1061 contains multiple devices. If you want multiple devices to be
1062 replayed concurrently to multiple redirected devices you must
1063 blkparse your trace into separate traces and replay them with
1064 independent fio invocations. Unfortuantely this also breaks
1065 the strict time ordering between multiple device accesses.
1067 write_bw_log=str If given, write a bandwidth log of the jobs in this job
1068 file. Can be used to store data of the bandwidth of the
1069 jobs in their lifetime. The included fio_generate_plots
1070 script uses gnuplot to turn these text files into nice
1071 graphs. See write_log_log for behaviour of given
1072 filename. For this option, the postfix is _bw.log.
1074 write_lat_log=str Same as write_bw_log, except that this option stores io
1075 submission, completion, and total latencies instead. If no
1076 filename is given with this option, the default filename of
1077 "jobname_type.log" is used. Even if the filename is given,
1078 fio will still append the type of log. So if one specifies
1082 The actual log names will be foo_slat.log, foo_slat.log,
1083 and foo_lat.log. This helps fio_generate_plot fine the logs
1086 lockmem=int Pin down the specified amount of memory with mlock(2). Can
1087 potentially be used instead of removing memory or booting
1088 with less memory to simulate a smaller amount of memory.
1090 exec_prerun=str Before running this job, issue the command specified
1093 exec_postrun=str After the job completes, issue the command specified
1096 ioscheduler=str Attempt to switch the device hosting the file to the specified
1097 io scheduler before running.
1099 cpuload=int If the job is a CPU cycle eater, attempt to use the specified
1100 percentage of CPU cycles.
1102 cpuchunks=int If the job is a CPU cycle eater, split the load into
1103 cycles of the given time. In microseconds.
1105 disk_util=bool Generate disk utilization statistics, if the platform
1106 supports it. Defaults to on.
1108 disable_lat=bool Disable measurements of total latency numbers. Useful
1109 only for cutting back the number of calls to gettimeofday,
1110 as that does impact performance at really high IOPS rates.
1111 Note that to really get rid of a large amount of these
1112 calls, this option must be used with disable_slat and
1115 disable_clat=bool Disable measurements of completion latency numbers. See
1118 disable_slat=bool Disable measurements of submission latency numbers. See
1121 disable_bw=bool Disable measurements of throughput/bandwidth numbers. See
1124 clat_percentiles=bool Enable the reporting of percentiles of
1125 completion latencies.
1127 percentile_list=float_list Overwrite the default list of percentiles
1128 for completion latencies. Each number is a floating
1129 number in the range (0,100], and the maximum length of
1130 the list is 20. Use ':' to separate the numbers, and
1131 list the numbers in ascending order. For example,
1132 --percentile_list=99.5:99.9 will cause fio to report
1133 the values of completion latency below which 99.5% and
1134 99.9% of the observed latencies fell, respectively.
1136 gtod_reduce=bool Enable all of the gettimeofday() reducing options
1137 (disable_clat, disable_slat, disable_bw) plus reduce
1138 precision of the timeout somewhat to really shrink
1139 the gettimeofday() call count. With this option enabled,
1140 we only do about 0.4% of the gtod() calls we would have
1141 done if all time keeping was enabled.
1143 gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of
1144 execution to just getting the current time. Fio (and
1145 databases, for instance) are very intensive on gettimeofday()
1146 calls. With this option, you can set one CPU aside for
1147 doing nothing but logging current time to a shared memory
1148 location. Then the other threads/processes that run IO
1149 workloads need only copy that segment, instead of entering
1150 the kernel with a gettimeofday() call. The CPU set aside
1151 for doing these time calls will be excluded from other
1152 uses. Fio will manually clear it from the CPU mask of other
1155 continue_on_error=bool Normally fio will exit the job on the first observed
1156 failure. If this option is set, fio will continue the job when
1157 there is a 'non-fatal error' (EIO or EILSEQ) until the runtime
1158 is exceeded or the I/O size specified is completed. If this
1159 option is used, there are two more stats that are appended,
1160 the total error count and the first error. The error field
1161 given in the stats is the first error that was hit during the
1164 cgroup=str Add job to this control group. If it doesn't exist, it will
1165 be created. The system must have a mounted cgroup blkio
1166 mount point for this to work. If your system doesn't have it
1167 mounted, you can do so with:
1169 # mount -t cgroup -o blkio none /cgroup
1171 cgroup_weight=int Set the weight of the cgroup to this value. See
1172 the documentation that comes with the kernel, allowed values
1173 are in the range of 100..1000.
1175 cgroup_nodelete=bool Normally fio will delete the cgroups it has created after
1176 the job completion. To override this behavior and to leave
1177 cgroups around after the job completion, set cgroup_nodelete=1.
1178 This can be useful if one wants to inspect various cgroup
1179 files after job completion. Default: false
1181 uid=int Instead of running as the invoking user, set the user ID to
1182 this value before the thread/process does any work.
1184 gid=int Set group ID, see uid.
1186 6.0 Interpreting the output
1187 ---------------------------
1189 fio spits out a lot of output. While running, fio will display the
1190 status of the jobs created. An example of that would be:
1192 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1194 The characters inside the square brackets denote the current status of
1195 each thread. The possible values (in typical life cycle order) are:
1199 P Thread setup, but not started.
1201 I Thread initialized, waiting.
1202 p Thread running pre-reading file(s).
1203 R Running, doing sequential reads.
1204 r Running, doing random reads.
1205 W Running, doing sequential writes.
1206 w Running, doing random writes.
1207 M Running, doing mixed sequential reads/writes.
1208 m Running, doing mixed random reads/writes.
1209 F Running, currently waiting for fsync()
1210 V Running, doing verification of written data.
1211 E Thread exited, not reaped by main thread yet.
1214 The other values are fairly self explanatory - number of threads
1215 currently running and doing io, rate of io since last check (read speed
1216 listed first, then write speed), and the estimated completion percentage
1217 and time for the running group. It's impossible to estimate runtime of
1218 the following groups (if any).
1220 When fio is done (or interrupted by ctrl-c), it will show the data for
1221 each thread, group of threads, and disks in that order. For each data
1222 direction, the output looks like:
1224 Client1 (g=0): err= 0:
1225 write: io= 32MB, bw= 666KB/s, iops=89 , runt= 50320msec
1226 slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92
1227 clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82
1228 bw (KB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68
1229 cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17
1230 IO depths : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0%
1231 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
1232 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
1233 issued r/w: total=0/32768, short=0/0
1234 lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%,
1235 lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0%
1237 The client number is printed, along with the group id and error of that
1238 thread. Below is the io statistics, here for writes. In the order listed,
1241 io= Number of megabytes io performed
1242 bw= Average bandwidth rate
1243 iops= Average IOs performed per second
1244 runt= The runtime of that thread
1245 slat= Submission latency (avg being the average, stdev being the
1246 standard deviation). This is the time it took to submit
1247 the io. For sync io, the slat is really the completion
1248 latency, since queue/complete is one operation there. This
1249 value can be in milliseconds or microseconds, fio will choose
1250 the most appropriate base and print that. In the example
1251 above, milliseconds is the best scale.
1252 clat= Completion latency. Same names as slat, this denotes the
1253 time from submission to completion of the io pieces. For
1254 sync io, clat will usually be equal (or very close) to 0,
1255 as the time from submit to complete is basically just
1256 CPU time (io has already been done, see slat explanation).
1257 bw= Bandwidth. Same names as the xlat stats, but also includes
1258 an approximate percentage of total aggregate bandwidth
1259 this thread received in this group. This last value is
1260 only really useful if the threads in this group are on the
1261 same disk, since they are then competing for disk access.
1262 cpu= CPU usage. User and system time, along with the number
1263 of context switches this thread went through, usage of
1264 system and user time, and finally the number of major
1265 and minor page faults.
1266 IO depths= The distribution of io depths over the job life time. The
1267 numbers are divided into powers of 2, so for example the
1268 16= entries includes depths up to that value but higher
1269 than the previous entry. In other words, it covers the
1270 range from 16 to 31.
1271 IO submit= How many pieces of IO were submitting in a single submit
1272 call. Each entry denotes that amount and below, until
1273 the previous entry - eg, 8=100% mean that we submitted
1274 anywhere in between 5-8 ios per submit call.
1275 IO complete= Like the above submit number, but for completions instead.
1276 IO issued= The number of read/write requests issued, and how many
1278 IO latencies= The distribution of IO completion latencies. This is the
1279 time from when IO leaves fio and when it gets completed.
1280 The numbers follow the same pattern as the IO depths,
1281 meaning that 2=1.6% means that 1.6% of the IO completed
1282 within 2 msecs, 20=12.8% means that 12.8% of the IO
1283 took more than 10 msecs, but less than (or equal to) 20 msecs.
1285 After each client has been listed, the group statistics are printed. They
1286 will look like this:
1288 Run status group 0 (all jobs):
1289 READ: io=64MB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec
1290 WRITE: io=64MB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec
1292 For each data direction, it prints:
1294 io= Number of megabytes io performed.
1295 aggrb= Aggregate bandwidth of threads in this group.
1296 minb= The minimum average bandwidth a thread saw.
1297 maxb= The maximum average bandwidth a thread saw.
1298 mint= The smallest runtime of the threads in that group.
1299 maxt= The longest runtime of the threads in that group.
1301 And finally, the disk statistics are printed. They will look like this:
1303 Disk stats (read/write):
1304 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
1306 Each value is printed for both reads and writes, with reads first. The
1309 ios= Number of ios performed by all groups.
1310 merge= Number of merges io the io scheduler.
1311 ticks= Number of ticks we kept the disk busy.
1312 io_queue= Total time spent in the disk queue.
1313 util= The disk utilization. A value of 100% means we kept the disk
1314 busy constantly, 50% would be a disk idling half of the time.
1320 For scripted usage where you typically want to generate tables or graphs
1321 of the results, fio can output the results in a semicolon separated format.
1322 The format is one long line of values, such as:
1324 2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00%
1325 A description of this job goes here.
1327 The job description (if provided) follows on a second line.
1329 To enable terse output, use the --minimal command line option. The first
1330 value is the version of the terse output format. If the output has to
1331 be changed for some reason, this number will be incremented by 1 to
1332 signify that change.
1334 Split up, the format is as follows:
1336 version, jobname, groupid, error
1338 KB IO, bandwidth (KB/sec), runtime (msec)
1339 Submission latency: min, max, mean, deviation
1340 Completion latency: min, max, mean, deviation
1341 Total latency: min, max, mean, deviation
1342 Bw: min, max, aggregate percentage of total, mean, deviation
1344 KB IO, bandwidth (KB/sec), runtime (msec)
1345 Submission latency: min, max, mean, deviation
1346 Completion latency: min, max, mean, deviation
1347 Total latency: min, max, mean, deviation
1348 Bw: min, max, aggregate percentage of total, mean, deviation
1349 CPU usage: user, system, context switches, major faults, minor faults
1350 IO depths: <=1, 2, 4, 8, 16, 32, >=64
1351 IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1352 IO latencies milliseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1353 Additional Info (dependant on continue_on_error, default off): total # errors, first error code
1355 Additional Info (dependant on description being set): Text description
1358 8.0 Trace file format
1359 ---------------------
1360 There are two trace file format that you can encounter. The older (v1) format
1361 is unsupported since version 1.20-rc3 (March 2008). It will still be described
1362 below in case that you get an old trace and want to understand it.
1364 In any case the trace is a simple text file with a single action per line.
1367 8.1 Trace file format v1
1368 ------------------------
1369 Each line represents a single io action in the following format:
1373 where rw=0/1 for read/write, and the offset and length entries being in bytes.
1375 This format is not supported in Fio versions => 1.20-rc3.
1378 8.2 Trace file format v2
1379 ------------------------
1380 The second version of the trace file format was added in Fio version 1.17.
1381 It allows to access more then one file per trace and has a bigger set of
1382 possible file actions.
1384 The first line of the trace file has to be:
1388 Following this can be lines in two different formats, which are described below.
1390 The file management format:
1394 The filename is given as an absolute path. The action can be one of these:
1396 add Add the given filename to the trace
1397 open Open the file with the given filename. The filename has to have
1398 been added with the add action before.
1399 close Close the file with the given filename. The file has to have been
1403 The file io action format:
1405 filename action offset length
1407 The filename is given as an absolute path, and has to have been added and opened
1408 before it can be used with this format. The offset and length are given in
1409 bytes. The action can be one of these:
1411 wait Wait for 'offset' microseconds. Everything below 100 is discarded.
1412 read Read 'length' bytes beginning from 'offset'
1413 write Write 'length' bytes beginning from 'offset'
1414 sync fsync() the file
1415 datasync fdatasync() the file
1416 trim trim the given file from the given 'offset' for 'length' bytes
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