1 .TH fio 1 "September 2007" "User Manual"
3 fio \- flexible I/O tester
6 [\fIoptions\fR] [\fIjobfile\fR]...
9 is a tool that will spawn a number of threads or processes doing a
10 particular type of I/O action as specified by the user.
11 The typical use of fio is to write a job file matching the I/O load
12 one wants to simulate.
15 .BI \-\-debug \fR=\fPtype
16 Enable verbose tracing of various fio actions. May be `all' for all types
17 or individual types separated by a comma (eg \-\-debug=io,file). `help' will
18 list all available tracing options.
20 .BI \-\-output \fR=\fPfilename
21 Write output to \fIfilename\fR.
23 .BI \-\-timeout \fR=\fPtimeout
24 Limit run time to \fItimeout\fR seconds.
27 Generate per-job latency logs.
30 Generate per-job bandwidth logs.
33 Print statistics in a terse, semicolon-delimited format.
36 Display version information and exit.
38 .BI \-\-terse\-version \fR=\fPversion
39 Set terse version output format (Current version 3, or older version 2).
42 Display usage information and exit.
44 .BI \-\-cmdhelp \fR=\fPcommand
45 Print help information for \fIcommand\fR. May be `all' for all commands.
47 .BI \-\-enghelp \fR=\fPioengine[,command]
48 List all commands defined by \fIioengine\fR, or print help for \fIcommand\fR defined by \fIioengine\fR.
50 .BI \-\-showcmd \fR=\fPjobfile
51 Convert \fIjobfile\fR to a set of command-line options.
54 Enable read-only safety checks.
56 .BI \-\-eta \fR=\fPwhen
57 Specifies when real-time ETA estimate should be printed. \fIwhen\fR may
58 be one of `always', `never' or `auto'.
61 Turn on safety read-only checks, preventing any attempted write.
63 .BI \-\-section \fR=\fPsec
64 Only run section \fIsec\fR from job file. Multiple of these options can be given, adding more sections to run.
66 .BI \-\-alloc\-size \fR=\fPkb
67 Set the internal smalloc pool size to \fIkb\fP kilobytes.
69 .BI \-\-warnings\-fatal
70 All fio parser warnings are fatal, causing fio to exit with an error.
72 .BI \-\-max\-jobs \fR=\fPnr
73 Set the maximum allowed number of jobs (threads/processes) to suport.
75 .BI \-\-server \fR=\fPargs
76 Start a backend server, with \fIargs\fP specifying what to listen to. See client/server section.
78 .BI \-\-daemonize \fR=\fPpidfile
79 Background a fio server, writing the pid to the given pid file.
81 .BI \-\-client \fR=\fPhost
82 Instead of running the jobs locally, send and run them on the given host.
84 Job files are in `ini' format. They consist of one or more
85 job definitions, which begin with a job name in square brackets and
86 extend to the next job name. The job name can be any ASCII string
87 except `global', which has a special meaning. Following the job name is
88 a sequence of zero or more parameters, one per line, that define the
89 behavior of the job. Any line starting with a `;' or `#' character is
90 considered a comment and ignored.
92 If \fIjobfile\fR is specified as `-', the job file will be read from
95 The global section contains default parameters for jobs specified in the
96 job file. A job is only affected by global sections residing above it,
97 and there may be any number of global sections. Specific job definitions
98 may override any parameter set in global sections.
101 Some parameters may take arguments of a specific type. The types used are:
104 String: a sequence of alphanumeric characters.
107 SI integer: a whole number, possibly containing a suffix denoting the base unit
108 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
109 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
110 respectively. The suffix is not case sensitive. If prefixed with '0x', the
111 value is assumed to be base 16 (hexadecimal). A suffix may include a trailing 'b',
112 for instance 'kb' is identical to 'k'. You can specify a base 10 value
113 by using 'KiB', 'MiB', 'GiB', etc. This is useful for disk drives where
114 values are often given in base 10 values. Specifying '30GiB' will get you
118 Boolean: a true or false value. `0' denotes false, `1' denotes true.
121 Integer range: a range of integers specified in the format
122 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
123 \fIupper\fR may contain a suffix as described above. If an option allows two
124 sets of ranges, they are separated with a `,' or `/' character. For example:
128 List of floating numbers: A list of floating numbers, separated by
133 May be used to override the job name. On the command line, this parameter
134 has the special purpose of signalling the start of a new job.
136 .BI description \fR=\fPstr
137 Human-readable description of the job. It is printed when the job is run, but
138 otherwise has no special purpose.
140 .BI directory \fR=\fPstr
141 Prefix filenames with this directory. Used to place files in a location other
144 .BI filename \fR=\fPstr
146 normally makes up a file name based on the job name, thread number, and file
147 number. If you want to share files between threads in a job or several jobs,
148 specify a \fIfilename\fR for each of them to override the default.
149 If the I/O engine is file-based, you can specify
150 a number of files by separating the names with a `:' character. `\-' is a
151 reserved name, meaning stdin or stdout, depending on the read/write direction
154 .BI lockfile \fR=\fPstr
155 Fio defaults to not locking any files before it does IO to them. If a file or
156 file descriptor is shared, fio can serialize IO to that file to make the end
157 result consistent. This is usual for emulating real workloads that share files.
163 No locking. This is the default.
166 Only one thread or process may do IO at the time, excluding all others.
169 Read-write locking on the file. Many readers may access the file at the same
170 time, but writes get exclusive access.
173 The option may be post-fixed with a lock batch number. If set, then each
174 thread/process may do that amount of IOs to the file before giving up the lock.
175 Since lock acquisition is expensive, batching the lock/unlocks will speed up IO.
178 .BI opendir \fR=\fPstr
179 Recursively open any files below directory \fIstr\fR.
181 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
182 Type of I/O pattern. Accepted values are:
199 Mixed sequential reads and writes.
202 Mixed random reads and writes.
205 For mixed I/O, the default split is 50/50. For certain types of io the result
206 may still be skewed a bit, since the speed may be different. It is possible to
207 specify a number of IO's to do before getting a new offset, this is one by
208 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
209 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
210 value of 8. If the postfix is used with a sequential IO pattern, then the value
211 specified will be added to the generated offset for each IO. For instance,
212 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
213 into sequential IO with holes. See the \fBrw_sequencer\fR option.
216 .BI rw_sequencer \fR=\fPstr
217 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
218 then this option controls how that number modifies the IO offset being
219 generated. Accepted values are:
224 Generate sequential offset
227 Generate the same offset
230 \fBsequential\fR is only useful for random IO, where fio would normally
231 generate a new random offset for every IO. If you append eg 8 to randread, you
232 would get a new random offset for every 8 IO's. The result would be a seek for
233 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
234 that. As sequential IO is already sequential, setting \fBsequential\fR for that
235 would not result in any differences. \fBidentical\fR behaves in a similar
236 fashion, except it sends the same offset 8 number of times before generating a
241 .BI kb_base \fR=\fPint
242 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
243 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
244 reasons. Allow values are 1024 or 1000, with 1024 being the default.
246 .BI randrepeat \fR=\fPbool
247 Seed the random number generator in a predictable way so results are repeatable
248 across runs. Default: true.
250 .BI use_os_rand \fR=\fPbool
251 Fio can either use the random generator supplied by the OS to generator random
252 offsets, or it can use it's own internal generator (based on Tausworthe).
253 Default is to use the internal generator, which is often of better quality and
254 faster. Default: false.
256 .BI fallocate \fR=\fPstr
257 Whether pre-allocation is performed when laying down files. Accepted values
263 Do not pre-allocate space.
266 Pre-allocate via posix_fallocate().
269 Pre-allocate via fallocate() with FALLOC_FL_KEEP_SIZE set.
272 Backward-compatible alias for 'none'.
275 Backward-compatible alias for 'posix'.
278 May not be available on all supported platforms. 'keep' is only
279 available on Linux. If using ZFS on Solaris this must be set to 'none'
280 because ZFS doesn't support it. Default: 'posix'.
283 .BI fadvise_hint \fR=\fPbool
284 Use of \fIposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
285 are likely to be issued. Default: true.
288 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
289 been transfered, unless limited by other options (\fBruntime\fR, for instance).
290 Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
291 divided between the available files for the job. If not set, fio will use the
292 full size of the given files or devices. If the the files do not exist, size
293 must be given. It is also possible to give size as a percentage between 1 and
294 100. If size=20% is given, fio will use 20% of the full size of the given files
297 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
298 Sets size to something really large and waits for ENOSPC (no space left on
299 device) as the terminating condition. Only makes sense with sequential write.
300 For a read workload, the mount point will be filled first then IO started on
301 the result. This option doesn't make sense if operating on a raw device node,
302 since the size of that is already known by the file system. Additionally,
303 writing beyond end-of-device will not return ENOSPC there.
305 .BI filesize \fR=\fPirange
306 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
307 for files at random within the given range, limited to \fBsize\fR in total (if
308 that is given). If \fBfilesize\fR is not specified, each created file is the
311 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
312 Block size for I/O units. Default: 4k. Values for reads and writes can be
313 specified separately in the format \fIread\fR,\fIwrite\fR, either of
314 which may be empty to leave that value at its default.
316 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
317 Specify a range of I/O block sizes. The issued I/O unit will always be a
318 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
319 to both reads and writes if only one range is given, but can be specified
320 separately with a comma seperating the values. Example: bsrange=1k-4k,2k-8k.
321 Also (see \fBblocksize\fR).
323 .BI bssplit \fR=\fPstr
324 This option allows even finer grained control of the block sizes issued,
325 not just even splits between them. With this option, you can weight various
326 block sizes for exact control of the issued IO for a job that has mixed
327 block sizes. The format of the option is bssplit=blocksize/percentage,
328 optionally adding as many definitions as needed separated by a colon.
329 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
330 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
331 splits to reads and writes. The format is identical to what the
332 \fBbs\fR option accepts, the read and write parts are separated with a
335 .B blocksize_unaligned\fR,\fP bs_unaligned
336 If set, any size in \fBblocksize_range\fR may be used. This typically won't
337 work with direct I/O, as that normally requires sector alignment.
339 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
340 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
341 the minimum blocksize given. Minimum alignment is typically 512b
342 for using direct IO, though it usually depends on the hardware block size.
343 This option is mutually exclusive with using a random map for files, so it
344 will turn off that option.
347 Initialise buffers with all zeros. Default: fill buffers with random data.
350 If this option is given, fio will refill the IO buffers on every submit. The
351 default is to only fill it at init time and reuse that data. Only makes sense
352 if zero_buffers isn't specified, naturally. If data verification is enabled,
353 refill_buffers is also automatically enabled.
355 .BI scramble_buffers \fR=\fPbool
356 If \fBrefill_buffers\fR is too costly and the target is using data
357 deduplication, then setting this option will slightly modify the IO buffer
358 contents to defeat normal de-dupe attempts. This is not enough to defeat
359 more clever block compression attempts, but it will stop naive dedupe
360 of blocks. Default: true.
362 .BI buffer_compress_percentage \fR=\fPint
363 If this is set, then fio will attempt to provide IO buffer content (on WRITEs)
364 that compress to the specified level. Fio does this by providing a mix of
365 random data and zeroes. Note that this is per block size unit, for file/disk
366 wide compression level that matches this setting, you'll also want to set
367 \fBrefill_buffers\fR.
369 .BI buffer_compress_chunk \fR=\fPint
370 See \fBbuffer_compress_percentage\fR. This setting allows fio to manage how
371 big the ranges of random data and zeroed data is. Without this set, fio will
372 provide \fBbuffer_compress_percentage\fR of blocksize random data, followed by
373 the remaining zeroed. With this set to some chunk size smaller than the block
374 size, fio can alternate random and zeroed data throughout the IO buffer.
376 .BI nrfiles \fR=\fPint
377 Number of files to use for this job. Default: 1.
379 .BI openfiles \fR=\fPint
380 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
382 .BI file_service_type \fR=\fPstr
383 Defines how files to service are selected. The following types are defined:
388 Choose a file at random
391 Round robin over open files (default).
393 Do each file in the set sequentially.
396 The number of I/Os to issue before switching a new file can be specified by
397 appending `:\fIint\fR' to the service type.
400 .BI ioengine \fR=\fPstr
401 Defines how the job issues I/O. The following types are defined:
406 Basic \fIread\fR\|(2) or \fIwrite\fR\|(2) I/O. \fIfseek\fR\|(2) is used to
407 position the I/O location.
410 Basic \fIpread\fR\|(2) or \fIpwrite\fR\|(2) I/O.
413 Basic \fIreadv\fR\|(2) or \fIwritev\fR\|(2) I/O. Will emulate queuing by
414 coalescing adjacents IOs into a single submission.
417 Linux native asynchronous I/O. This ioengine defines engine specific options.
420 POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
423 Solaris native asynchronous I/O.
426 Windows native asynchronous I/O.
429 File is memory mapped with \fImmap\fR\|(2) and data copied using
433 \fIsplice\fR\|(2) is used to transfer the data and \fIvmsplice\fR\|(2) to
434 transfer data from user-space to the kernel.
437 Use the syslet system calls to make regular read/write asynchronous.
440 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
441 the target is an sg character device, we use \fIread\fR\|(2) and
442 \fIwrite\fR\|(2) for asynchronous I/O.
445 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
446 itself and for debugging and testing purposes.
449 Transfer over the network. The protocol to be used can be defined with the
450 \fBprotocol\fR parameter. Depending on the protocol, \fBfilename\fR,
451 \fBhostname\fR, \fBport\fR, or \fBlisten\fR must be specified.
452 This ioengine defines engine specific options.
455 Like \fBnet\fR, but uses \fIsplice\fR\|(2) and \fIvmsplice\fR\|(2) to map data
456 and send/receive. This ioengine defines engine specific options.
459 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
460 \fBcpucycles\fR parameters.
463 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
464 approach to asycnronous I/O.
466 See <http://www.xmailserver.org/guasi\-lib.html>.
469 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
470 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
473 Loads an external I/O engine object file. Append the engine filename as
478 .BI iodepth \fR=\fPint
479 Number of I/O units to keep in flight against the file. Note that increasing
480 iodepth beyond 1 will not affect synchronous ioengines (except for small
481 degress when verify_async is in use). Even async engines my impose OS
482 restrictions causing the desired depth not to be achieved. This may happen on
483 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
484 not async on that OS. Keep an eye on the IO depth distribution in the
485 fio output to verify that the achieved depth is as expected. Default: 1.
487 .BI iodepth_batch \fR=\fPint
488 Number of I/Os to submit at once. Default: \fBiodepth\fR.
490 .BI iodepth_batch_complete \fR=\fPint
491 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
492 means that we'll ask for a minimum of 1 IO in the retrieval process from the
493 kernel. The IO retrieval will go on until we hit the limit set by
494 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
495 completed events before queuing more IO. This helps reduce IO latency, at the
496 cost of more retrieval system calls.
498 .BI iodepth_low \fR=\fPint
499 Low watermark indicating when to start filling the queue again. Default:
502 .BI direct \fR=\fPbool
503 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
505 .BI buffered \fR=\fPbool
506 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
509 .BI offset \fR=\fPint
510 Offset in the file to start I/O. Data before the offset will not be touched.
512 .BI offset_increment \fR=\fPint
513 If this is provided, then the real offset becomes the
514 offset + offset_increment * thread_number, where the thread number is a counter
515 that starts at 0 and is incremented for each job. This option is useful if
516 there are several jobs which are intended to operate on a file in parallel in
517 disjoint segments, with even spacing between the starting points.
520 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
521 0, don't sync. Default: 0.
523 .BI fdatasync \fR=\fPint
524 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
525 data parts of the file. Default: 0.
527 .BI sync_file_range \fR=\fPstr:int
528 Use sync_file_range() for every \fRval\fP number of write operations. Fio will
529 track range of writes that have happened since the last sync_file_range() call.
530 \fRstr\fP can currently be one or more of:
534 SYNC_FILE_RANGE_WAIT_BEFORE
537 SYNC_FILE_RANGE_WRITE
540 SYNC_FILE_RANGE_WRITE
544 So if you do sync_file_range=wait_before,write:8, fio would use
545 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
546 Also see the sync_file_range(2) man page. This option is Linux specific.
548 .BI overwrite \fR=\fPbool
549 If writing, setup the file first and do overwrites. Default: false.
551 .BI end_fsync \fR=\fPbool
552 Sync file contents when job exits. Default: false.
554 .BI fsync_on_close \fR=\fPbool
555 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
556 it will happen on every close, not just at the end of the job. Default: false.
558 .BI rwmixcycle \fR=\fPint
559 How many milliseconds before switching between reads and writes for a mixed
560 workload. Default: 500ms.
562 .BI rwmixread \fR=\fPint
563 Percentage of a mixed workload that should be reads. Default: 50.
565 .BI rwmixwrite \fR=\fPint
566 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
567 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
568 overrides the first. This may interfere with a given rate setting, if fio is
569 asked to limit reads or writes to a certain rate. If that is the case, then
570 the distribution may be skewed. Default: 50.
573 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
574 this parameter is given, a new offset will be chosen without looking at past
575 I/O history. This parameter is mutually exclusive with \fBverify\fR.
577 .BI softrandommap \fR=\fPbool
578 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
579 fails to allocate the map, if this option is set it will continue without a
580 random block map. As coverage will not be as complete as with random maps, this
581 option is disabled by default.
584 Run job with given nice value. See \fInice\fR\|(2).
587 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
590 .BI prioclass \fR=\fPint
591 Set I/O priority class. See \fIionice\fR\|(1).
593 .BI thinktime \fR=\fPint
594 Stall job for given number of microseconds between issuing I/Os.
596 .BI thinktime_spin \fR=\fPint
597 Pretend to spend CPU time for given number of microseconds, sleeping the rest
598 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
600 .BI thinktime_blocks \fR=\fPint
601 Number of blocks to issue before waiting \fBthinktime\fR microseconds.
605 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
606 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
607 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
608 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
609 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
610 limit writes (to 500KB/sec), the latter will only limit reads.
612 .BI ratemin \fR=\fPint
613 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
614 Failing to meet this requirement will cause the job to exit. The same format
615 as \fBrate\fR is used for read vs write separation.
617 .BI rate_iops \fR=\fPint
618 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
619 specified independently of bandwidth. The same format as \fBrate\fR is used for
620 read vs write seperation. If \fBblocksize\fR is a range, the smallest block
621 size is used as the metric.
623 .BI rate_iops_min \fR=\fPint
624 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
625 is used for read vs write seperation.
627 .BI ratecycle \fR=\fPint
628 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
629 milliseconds. Default: 1000ms.
631 .BI cpumask \fR=\fPint
632 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
633 may run on. See \fBsched_setaffinity\fR\|(2).
635 .BI cpus_allowed \fR=\fPstr
636 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
638 .BI startdelay \fR=\fPint
639 Delay start of job for the specified number of seconds.
641 .BI runtime \fR=\fPint
642 Terminate processing after the specified number of seconds.
645 If given, run for the specified \fBruntime\fR duration even if the files are
646 completely read or written. The same workload will be repeated as many times
647 as \fBruntime\fR allows.
649 .BI ramp_time \fR=\fPint
650 If set, fio will run the specified workload for this amount of time before
651 logging any performance numbers. Useful for letting performance settle before
652 logging results, thus minimizing the runtime required for stable results. Note
653 that the \fBramp_time\fR is considered lead in time for a job, thus it will
654 increase the total runtime if a special timeout or runtime is specified.
656 .BI invalidate \fR=\fPbool
657 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
660 Use synchronous I/O for buffered writes. For the majority of I/O engines,
661 this means using O_SYNC. Default: false.
663 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
664 Allocation method for I/O unit buffer. Allowed values are:
669 Allocate memory with \fImalloc\fR\|(3).
672 Use shared memory buffers allocated through \fIshmget\fR\|(2).
675 Same as \fBshm\fR, but use huge pages as backing.
678 Use \fImmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
679 is given after the option in the format `:\fIfile\fR'.
682 Same as \fBmmap\fR, but use huge files as backing.
685 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
686 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
687 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
688 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
689 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
690 and the documentation for that. Normally you just need to echo an appropriate
691 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
695 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
696 This indiciates the memory alignment of the IO memory buffers. Note that the
697 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
698 the alignment of the following buffers are given by the \fBbs\fR used. In
699 other words, if using a \fBbs\fR that is a multiple of the page sized in the
700 system, all buffers will be aligned to this value. If using a \fBbs\fR that
701 is not page aligned, the alignment of subsequent IO memory buffers is the
702 sum of the \fBiomem_align\fR and \fBbs\fR used.
704 .BI hugepage\-size \fR=\fPint
705 Defines the size of a huge page. Must be at least equal to the system setting.
706 Should be a multiple of 1MB. Default: 4MB.
709 Terminate all jobs when one finishes. Default: wait for each job to finish.
711 .BI bwavgtime \fR=\fPint
712 Average bandwidth calculations over the given time in milliseconds. Default:
715 .BI iopsavgtime \fR=\fPint
716 Average IOPS calculations over the given time in milliseconds. Default:
719 .BI create_serialize \fR=\fPbool
720 If true, serialize file creation for the jobs. Default: true.
722 .BI create_fsync \fR=\fPbool
723 \fIfsync\fR\|(2) data file after creation. Default: true.
725 .BI create_on_open \fR=\fPbool
726 If true, the files are not created until they are opened for IO by the job.
728 .BI pre_read \fR=\fPbool
729 If this is given, files will be pre-read into memory before starting the given
730 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
731 pointless to pre-read and then drop the cache. This will only work for IO
732 engines that are seekable, since they allow you to read the same data
733 multiple times. Thus it will not work on eg network or splice IO.
735 .BI unlink \fR=\fPbool
736 Unlink job files when done. Default: false.
739 Specifies the number of iterations (runs of the same workload) of this job.
742 .BI do_verify \fR=\fPbool
743 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
746 .BI verify \fR=\fPstr
747 Method of verifying file contents after each iteration of the job. Allowed
752 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1
753 Store appropriate checksum in the header of each block. crc32c-intel is
754 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
755 not supported by the system.
758 Write extra information about each I/O (timestamp, block number, etc.). The
759 block number is verified. See \fBverify_pattern\fR as well.
762 Pretend to verify. Used for testing internals.
765 This option can be used for repeated burn-in tests of a system to make sure
766 that the written data is also correctly read back. If the data direction given
767 is a read or random read, fio will assume that it should verify a previously
768 written file. If the data direction includes any form of write, the verify will
769 be of the newly written data.
772 .BI verify_sort \fR=\fPbool
773 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
774 read them back in a sorted manner. Default: true.
776 .BI verify_offset \fR=\fPint
777 Swap the verification header with data somewhere else in the block before
778 writing. It is swapped back before verifying.
780 .BI verify_interval \fR=\fPint
781 Write the verification header for this number of bytes, which should divide
782 \fBblocksize\fR. Default: \fBblocksize\fR.
784 .BI verify_pattern \fR=\fPstr
785 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
786 with totally random bytes, but sometimes it's interesting to fill with a known
787 pattern for io verification purposes. Depending on the width of the pattern,
788 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
789 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
790 has to be a hex number that starts with either "0x" or "0X". Use with
793 .BI verify_fatal \fR=\fPbool
794 If true, exit the job on the first observed verification failure. Default:
797 .BI verify_dump \fR=\fPbool
798 If set, dump the contents of both the original data block and the data block we
799 read off disk to files. This allows later analysis to inspect just what kind of
800 data corruption occurred. Off by default.
802 .BI verify_async \fR=\fPint
803 Fio will normally verify IO inline from the submitting thread. This option
804 takes an integer describing how many async offload threads to create for IO
805 verification instead, causing fio to offload the duty of verifying IO contents
806 to one or more separate threads. If using this offload option, even sync IO
807 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
808 allows them to have IO in flight while verifies are running.
810 .BI verify_async_cpus \fR=\fPstr
811 Tell fio to set the given CPU affinity on the async IO verification threads.
812 See \fBcpus_allowed\fP for the format used.
814 .BI verify_backlog \fR=\fPint
815 Fio will normally verify the written contents of a job that utilizes verify
816 once that job has completed. In other words, everything is written then
817 everything is read back and verified. You may want to verify continually
818 instead for a variety of reasons. Fio stores the meta data associated with an
819 IO block in memory, so for large verify workloads, quite a bit of memory would
820 be used up holding this meta data. If this option is enabled, fio will write
821 only N blocks before verifying these blocks.
823 .BI verify_backlog_batch \fR=\fPint
824 Control how many blocks fio will verify if verify_backlog is set. If not set,
825 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
826 read back and verified). If \fBverify_backlog_batch\fR is less than
827 \fBverify_backlog\fR then not all blocks will be verified, if
828 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
829 will be verified more than once.
831 .B stonewall "\fR,\fP wait_for_previous"
832 Wait for preceding jobs in the job file to exit before starting this one.
833 \fBstonewall\fR implies \fBnew_group\fR.
836 Start a new reporting group. If not given, all jobs in a file will be part
837 of the same reporting group, unless separated by a stonewall.
839 .BI numjobs \fR=\fPint
840 Number of clones (processes/threads performing the same workload) of this job.
844 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
848 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
849 with \fBfork\fR\|(2).
851 .BI zonesize \fR=\fPint
852 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
854 .BI zoneskip \fR=\fPint
855 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
858 .BI write_iolog \fR=\fPstr
859 Write the issued I/O patterns to the specified file. Specify a separate file
860 for each job, otherwise the iologs will be interspersed and the file may be
863 .BI read_iolog \fR=\fPstr
864 Replay the I/O patterns contained in the specified file generated by
865 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
867 .BI replay_no_stall \fR=\fPint
868 While replaying I/O patterns using \fBread_iolog\fR the default behavior
869 attempts to respect timing information between I/Os. Enabling
870 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
871 still respecting ordering.
873 .BI replay_redirect \fR=\fPstr
874 While replaying I/O patterns using \fBread_iolog\fR the default behavior
875 is to replay the IOPS onto the major/minor device that each IOP was recorded
876 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
877 single specified device regardless of the device it was recorded from.
879 .BI write_bw_log \fR=\fPstr
880 If given, write a bandwidth log of the jobs in this job file. Can be used to
881 store data of the bandwidth of the jobs in their lifetime. The included
882 fio_generate_plots script uses gnuplot to turn these text files into nice
883 graphs. See \fBwrite_log_log\fR for behaviour of given filename. For this
884 option, the postfix is _bw.log.
886 .BI write_lat_log \fR=\fPstr
887 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
888 filename is given with this option, the default filename of "jobname_type.log"
889 is used. Even if the filename is given, fio will still append the type of log.
891 .BI write_iops_log \fR=\fPstr
892 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
893 option, the default filename of "jobname_type.log" is used. Even if the
894 filename is given, fio will still append the type of log.
896 .BI log_avg_msec \fR=\fPint
897 By default, fio will log an entry in the iops, latency, or bw log for every
898 IO that completes. When writing to the disk log, that can quickly grow to a
899 very large size. Setting this option makes fio average the each log entry
900 over the specified period of time, reducing the resolution of the log.
903 .BI disable_lat \fR=\fPbool
904 Disable measurements of total latency numbers. Useful only for cutting
905 back the number of calls to gettimeofday, as that does impact performance at
906 really high IOPS rates. Note that to really get rid of a large amount of these
907 calls, this option must be used with disable_slat and disable_bw as well.
909 .BI disable_clat \fR=\fPbool
910 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
912 .BI disable_slat \fR=\fPbool
913 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
915 .BI disable_bw_measurement \fR=\fPbool
916 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
918 .BI lockmem \fR=\fPint
919 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
920 simulate a smaller amount of memory.
922 .BI exec_prerun \fR=\fPstr
923 Before running the job, execute the specified command with \fBsystem\fR\|(3).
925 .BI exec_postrun \fR=\fPstr
926 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
928 .BI ioscheduler \fR=\fPstr
929 Attempt to switch the device hosting the file to the specified I/O scheduler.
931 .BI cpuload \fR=\fPint
932 If the job is a CPU cycle-eater, attempt to use the specified percentage of
935 .BI cpuchunks \fR=\fPint
936 If the job is a CPU cycle-eater, split the load into cycles of the
937 given time in milliseconds.
939 .BI disk_util \fR=\fPbool
940 Generate disk utilization statistics if the platform supports it. Default: true.
942 .BI gtod_reduce \fR=\fPbool
943 Enable all of the gettimeofday() reducing options (disable_clat, disable_slat,
944 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
945 gettimeofday() call count. With this option enabled, we only do about 0.4% of
946 the gtod() calls we would have done if all time keeping was enabled.
948 .BI gtod_cpu \fR=\fPint
949 Sometimes it's cheaper to dedicate a single thread of execution to just getting
950 the current time. Fio (and databases, for instance) are very intensive on
951 gettimeofday() calls. With this option, you can set one CPU aside for doing
952 nothing but logging current time to a shared memory location. Then the other
953 threads/processes that run IO workloads need only copy that segment, instead of
954 entering the kernel with a gettimeofday() call. The CPU set aside for doing
955 these time calls will be excluded from other uses. Fio will manually clear it
956 from the CPU mask of other jobs.
958 .BI cgroup \fR=\fPstr
959 Add job to this control group. If it doesn't exist, it will be created.
960 The system must have a mounted cgroup blkio mount point for this to work. If
961 your system doesn't have it mounted, you can do so with:
963 # mount \-t cgroup \-o blkio none /cgroup
965 .BI cgroup_weight \fR=\fPint
966 Set the weight of the cgroup to this value. See the documentation that comes
967 with the kernel, allowed values are in the range of 100..1000.
969 .BI cgroup_nodelete \fR=\fPbool
970 Normally fio will delete the cgroups it has created after the job completion.
971 To override this behavior and to leave cgroups around after the job completion,
972 set cgroup_nodelete=1. This can be useful if one wants to inspect various
973 cgroup files after job completion. Default: false
976 Instead of running as the invoking user, set the user ID to this value before
977 the thread/process does any work.
980 Set group ID, see \fBuid\fR.
982 .BI flow_id \fR=\fPint
983 The ID of the flow. If not specified, it defaults to being a global flow. See
987 Weight in token-based flow control. If this value is used, then there is a
988 \fBflow counter\fR which is used to regulate the proportion of activity between
989 two or more jobs. fio attempts to keep this flow counter near zero. The
990 \fBflow\fR parameter stands for how much should be added or subtracted to the
991 flow counter on each iteration of the main I/O loop. That is, if one job has
992 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
993 1:8 ratio in how much one runs vs the other.
995 .BI flow_watermark \fR=\fPint
996 The maximum value that the absolute value of the flow counter is allowed to
997 reach before the job must wait for a lower value of the counter.
999 .BI flow_sleep \fR=\fPint
1000 The period of time, in microseconds, to wait after the flow watermark has been
1001 exceeded before retrying operations
1003 .BI clat_percentiles \fR=\fPbool
1004 Enable the reporting of percentiles of completion latencies.
1006 .BI percentile_list \fR=\fPfloat_list
1007 Overwrite the default list of percentiles for completion
1008 latencies. Each number is a floating number in the range (0,100], and
1009 the maximum length of the list is 20. Use ':' to separate the
1010 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1011 report the values of completion latency below which 99.5% and 99.9% of
1012 the observed latencies fell, respectively.
1013 .SS "Ioengine Parameters List"
1014 Some parameters are only valid when a specific ioengine is in use. These are
1015 used identically to normal parameters, with the caveat that when used on the
1016 command line, the must come after the ioengine that defines them is selected.
1018 .BI (libaio)userspace_reap
1019 Normally, with the libaio engine in use, fio will use
1020 the io_getevents system call to reap newly returned events.
1021 With this flag turned on, the AIO ring will be read directly
1022 from user-space to reap events. The reaping mode is only
1023 enabled when polling for a minimum of 0 events (eg when
1024 iodepth_batch_complete=0).
1026 .BI (net,netsplice)hostname \fR=\fPstr
1027 The host name or IP address to use for TCP or UDP based IO.
1028 If the job is a TCP listener or UDP reader, the hostname is not
1029 used and must be omitted.
1031 .BI (net,netsplice)port \fR=\fPint
1032 The TCP or UDP port to bind to or connect to.
1034 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1035 The network protocol to use. Accepted values are:
1040 Transmission control protocol
1043 Unreliable datagram protocol
1049 When the protocol is TCP or UDP, the port must also be given,
1050 as well as the hostname if the job is a TCP listener or UDP
1051 reader. For unix sockets, the normal filename option should be
1052 used and the port is invalid.
1055 .BI (net,netsplice)listen
1056 For TCP network connections, tell fio to listen for incoming
1057 connections rather than initiating an outgoing connection. The
1058 hostname must be omitted if this option is used.
1060 While running, \fBfio\fR will display the status of the created jobs. For
1064 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1067 The characters in the first set of brackets denote the current status of each
1068 threads. The possible values are:
1074 Setup but not started.
1080 Initialized, waiting.
1083 Running, doing sequential reads.
1086 Running, doing random reads.
1089 Running, doing sequential writes.
1092 Running, doing random writes.
1095 Running, doing mixed sequential reads/writes.
1098 Running, doing mixed random reads/writes.
1101 Running, currently waiting for \fBfsync\fR\|(2).
1104 Running, verifying written data.
1107 Exited, not reaped by main thread.
1110 Exited, thread reaped.
1114 The second set of brackets shows the estimated completion percentage of
1115 the current group. The third set shows the read and write I/O rate,
1116 respectively. Finally, the estimated run time of the job is displayed.
1118 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1119 for each thread, each group of threads, and each disk, in that order.
1121 Per-thread statistics first show the threads client number, group-id, and
1122 error code. The remaining figures are as follows:
1126 Number of megabytes of I/O performed.
1129 Average data rate (bandwidth).
1135 Submission latency minimum, maximum, average and standard deviation. This is
1136 the time it took to submit the I/O.
1139 Completion latency minimum, maximum, average and standard deviation. This
1140 is the time between submission and completion.
1143 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1144 and standard deviation.
1147 CPU usage statistics. Includes user and system time, number of context switches
1148 this thread went through and number of major and minor page faults.
1151 Distribution of I/O depths. Each depth includes everything less than (or equal)
1152 to it, but greater than the previous depth.
1155 Number of read/write requests issued, and number of short read/write requests.
1158 Distribution of I/O completion latencies. The numbers follow the same pattern
1162 The group statistics show:
1167 Number of megabytes I/O performed.
1170 Aggregate bandwidth of threads in the group.
1173 Minimum average bandwidth a thread saw.
1176 Maximum average bandwidth a thread saw.
1179 Shortest runtime of threads in the group.
1182 Longest runtime of threads in the group.
1186 Finally, disk statistics are printed with reads first:
1191 Number of I/Os performed by all groups.
1194 Number of merges in the I/O scheduler.
1197 Number of ticks we kept the disk busy.
1200 Total time spent in the disk queue.
1207 If the \fB\-\-minimal\fR option is given, the results will be printed in a
1208 semicolon-delimited format suitable for scripted use - a job description
1209 (if provided) follows on a new line. Note that the first
1210 number in the line is the version number. If the output has to be changed
1211 for some reason, this number will be incremented by 1 to signify that
1212 change. The fields are:
1215 .B terse version, fio version, jobname, groupid, error
1219 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1223 .B min, max, mean, standard deviation
1227 .B min, max, mean, standard deviation
1229 Completion latency percentiles (20 fields):
1231 .B Xth percentile=usec
1235 .B min, max, mean, standard deviation
1239 .B min, max, aggregate percentage of total, mean, standard deviation
1245 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1249 .B min, max, mean, standard deviation
1253 .B min, max, mean, standard deviation
1255 Completion latency percentiles (20 fields):
1257 .B Xth percentile=usec
1261 .B min, max, mean, standard deviation
1265 .B min, max, aggregate percentage of total, mean, standard deviation
1271 .B user, system, context switches, major page faults, minor page faults
1274 IO depth distribution:
1276 .B <=1, 2, 4, 8, 16, 32, >=64
1279 IO latency distribution:
1283 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1287 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1291 Disk utilization (1 for each disk used):
1293 .B name, read ios, write ios, read merges, write merges, read ticks, write ticks, read in-queue time, write in-queue time, disk utilization percentage
1296 Error Info (dependent on continue_on_error, default off):
1298 .B total # errors, first error code
1301 .B text description (if provided in config - appears on newline)
1304 Normally you would run fio as a stand-alone application on the machine
1305 where the IO workload should be generated. However, it is also possible to
1306 run the frontend and backend of fio separately. This makes it possible to
1307 have a fio server running on the machine(s) where the IO workload should
1308 be running, while controlling it from another machine.
1310 To start the server, you would do:
1312 \fBfio \-\-server=args\fR
1314 on that machine, where args defines what fio listens to. The arguments
1315 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1316 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain socket.
1317 'hostname' is either a hostname or IP address, and 'port' is the port to
1318 listen to (only valid for TCP/IP, not a local socket). Some examples:
1322 Start a fio server, listening on all interfaces on the default port (8765).
1324 2) fio --server=ip:hostname,4444
1326 Start a fio server, listening on IP belonging to hostname and on port 4444.
1328 3) fio --server=ip6:::1,4444
1330 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1332 4) fio --server=,4444
1334 Start a fio server, listening on all interfaces on port 4444.
1336 5) fio --server=1.2.3.4
1338 Start a fio server, listening on IP 1.2.3.4 on the default port.
1340 6) fio --server=sock:/tmp/fio.sock
1342 Start a fio server, listening on the local socket /tmp/fio.sock.
1344 When a server is running, you can connect to it from a client. The client
1347 fio --local-args --client=server --remote-args <job file(s)>
1349 where --local-args are arguments that are local to the client where it is
1350 running, 'server' is the connect string, and --remote-args and <job file(s)>
1351 are sent to the server. The 'server' string follows the same format as it
1352 does on the server side, to allow IP/hostname/socket and port strings.
1353 You can connect to multiple clients as well, to do that you could run:
1355 fio --client=server2 --client=server2 <job file(s)>
1359 was written by Jens Axboe <jens.axboe@oracle.com>,
1360 now Jens Axboe <jaxboe@fusionio.com>.
1362 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1363 on documentation by Jens Axboe.
1364 .SH "REPORTING BUGS"
1365 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1368 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1370 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob