1 .TH fio 1 "October 2013" "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 \-\-runtime \fR=\fPruntime
24 Limit run time to \fIruntime\fR seconds.
27 Generate per-job latency logs.
30 Generate per-job bandwidth logs.
33 Print statistics in a terse, semicolon-delimited format.
36 Print statistics in selected mode AND terse, semicolon-delimited format.
39 Display version information and exit.
41 .BI \-\-terse\-version \fR=\fPversion
42 Set terse version output format (Current version 3, or older version 2).
45 Display usage information and exit.
48 Perform test and validation of internal CPU clock
50 .BI \-\-crctest[\fR=\fPtest]
51 Test the speed of the builtin checksumming functions. If no argument is given,
52 all of them are tested. Or a comma separated list can be passed, in which
53 case the given ones are tested.
55 .BI \-\-cmdhelp \fR=\fPcommand
56 Print help information for \fIcommand\fR. May be `all' for all commands.
58 .BI \-\-enghelp \fR=\fPioengine[,command]
59 List all commands defined by \fIioengine\fR, or print help for \fIcommand\fR defined by \fIioengine\fR.
61 .BI \-\-showcmd \fR=\fPjobfile
62 Convert \fIjobfile\fR to a set of command-line options.
64 .BI \-\-eta \fR=\fPwhen
65 Specifies when real-time ETA estimate should be printed. \fIwhen\fR may
66 be one of `always', `never' or `auto'.
68 .BI \-\-eta\-newline \fR=\fPtime
69 Force an ETA newline for every `time` period passed.
71 .BI \-\-status\-interval \fR=\fPtime
72 Report full output status every `time` period passed.
75 Turn on safety read-only checks, preventing any attempted write.
77 .BI \-\-section \fR=\fPsec
78 Only run section \fIsec\fR from job file. Multiple of these options can be given, adding more sections to run.
80 .BI \-\-alloc\-size \fR=\fPkb
81 Set the internal smalloc pool size to \fIkb\fP kilobytes.
83 .BI \-\-warnings\-fatal
84 All fio parser warnings are fatal, causing fio to exit with an error.
86 .BI \-\-max\-jobs \fR=\fPnr
87 Set the maximum allowed number of jobs (threads/processes) to support.
89 .BI \-\-server \fR=\fPargs
90 Start a backend server, with \fIargs\fP specifying what to listen to. See client/server section.
92 .BI \-\-daemonize \fR=\fPpidfile
93 Background a fio server, writing the pid to the given pid file.
95 .BI \-\-client \fR=\fPhost
96 Instead of running the jobs locally, send and run them on the given host.
98 .BI \-\-idle\-prof \fR=\fPoption
99 Report cpu idleness on a system or percpu basis (\fIoption\fP=system,percpu) or run unit work calibration only (\fIoption\fP=calibrate).
100 .SH "JOB FILE FORMAT"
101 Job files are in `ini' format. They consist of one or more
102 job definitions, which begin with a job name in square brackets and
103 extend to the next job name. The job name can be any ASCII string
104 except `global', which has a special meaning. Following the job name is
105 a sequence of zero or more parameters, one per line, that define the
106 behavior of the job. Any line starting with a `;' or `#' character is
107 considered a comment and ignored.
109 If \fIjobfile\fR is specified as `-', the job file will be read from
112 The global section contains default parameters for jobs specified in the
113 job file. A job is only affected by global sections residing above it,
114 and there may be any number of global sections. Specific job definitions
115 may override any parameter set in global sections.
118 Some parameters may take arguments of a specific type. The types used are:
121 String: a sequence of alphanumeric characters.
124 SI integer: a whole number, possibly containing a suffix denoting the base unit
125 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
126 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
127 respectively. If prefixed with '0x', the value is assumed to be base 16
128 (hexadecimal). A suffix may include a trailing 'b', for instance 'kb' is
129 identical to 'k'. You can specify a base 10 value by using 'KiB', 'MiB','GiB',
130 etc. This is useful for disk drives where values are often given in base 10
131 values. Specifying '30GiB' will get you 30*1000^3 bytes.
132 When specifying times the default suffix meaning changes, still denoting the
133 base unit of the value, but accepted suffixes are 'D' (days), 'H' (hours), 'M'
134 (minutes), 'S' Seconds, 'ms' milli seconds. Time values without a unit specify
136 The suffixes are not case sensitive.
139 Boolean: a true or false value. `0' denotes false, `1' denotes true.
142 Integer range: a range of integers specified in the format
143 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
144 \fIupper\fR may contain a suffix as described above. If an option allows two
145 sets of ranges, they are separated with a `,' or `/' character. For example:
149 List of floating numbers: A list of floating numbers, separated by
154 May be used to override the job name. On the command line, this parameter
155 has the special purpose of signalling the start of a new job.
157 .BI description \fR=\fPstr
158 Human-readable description of the job. It is printed when the job is run, but
159 otherwise has no special purpose.
161 .BI directory \fR=\fPstr
162 Prefix filenames with this directory. Used to place files in a location other
164 You can specify a number of directories by separating the names with a ':'
165 character. These directories will be assigned equally distributed to job clones
166 creates with \fInumjobs\fR as long as they are using generated filenames.
167 If specific \fIfilename(s)\fR are set fio will use the first listed directory,
168 and thereby matching the \fIfilename\fR semantic which generates a file each
169 clone if not specified, but let all clones use the same if set.
171 .BI filename \fR=\fPstr
173 normally makes up a file name based on the job name, thread number, and file
174 number. If you want to share files between threads in a job or several jobs,
175 specify a \fIfilename\fR for each of them to override the default.
176 If the I/O engine is file-based, you can specify
177 a number of files by separating the names with a `:' character. `\-' is a
178 reserved name, meaning stdin or stdout, depending on the read/write direction
181 .BI filename_format \fR=\fPstr
182 If sharing multiple files between jobs, it is usually necessary to have
183 fio generate the exact names that you want. By default, fio will name a file
184 based on the default file format specification of
185 \fBjobname.jobnumber.filenumber\fP. With this option, that can be
186 customized. Fio will recognize and replace the following keywords in this
192 The name of the worker thread or process.
195 The incremental number of the worker thread or process.
198 The incremental number of the file for that worker thread or process.
201 To have dependent jobs share a set of files, this option can be set to
202 have fio generate filenames that are shared between the two. For instance,
203 if \fBtestfiles.$filenum\fR is specified, file number 4 for any job will
204 be named \fBtestfiles.4\fR. The default of \fB$jobname.$jobnum.$filenum\fR
205 will be used if no other format specifier is given.
209 .BI lockfile \fR=\fPstr
210 Fio defaults to not locking any files before it does IO to them. If a file or
211 file descriptor is shared, fio can serialize IO to that file to make the end
212 result consistent. This is usual for emulating real workloads that share files.
218 No locking. This is the default.
221 Only one thread or process may do IO at the time, excluding all others.
224 Read-write locking on the file. Many readers may access the file at the same
225 time, but writes get exclusive access.
229 .BI opendir \fR=\fPstr
230 Recursively open any files below directory \fIstr\fR.
232 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
233 Type of I/O pattern. Accepted values are:
244 Sequential trim (Linux block devices only).
253 Random trim (Linux block devices only).
256 Mixed sequential reads and writes.
259 Mixed random reads and writes.
262 For mixed I/O, the default split is 50/50. For certain types of io the result
263 may still be skewed a bit, since the speed may be different. It is possible to
264 specify a number of IO's to do before getting a new offset, this is done by
265 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
266 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
267 value of 8. If the postfix is used with a sequential IO pattern, then the value
268 specified will be added to the generated offset for each IO. For instance,
269 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
270 into sequential IO with holes. See the \fBrw_sequencer\fR option.
273 .BI rw_sequencer \fR=\fPstr
274 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
275 then this option controls how that number modifies the IO offset being
276 generated. Accepted values are:
281 Generate sequential offset
284 Generate the same offset
287 \fBsequential\fR is only useful for random IO, where fio would normally
288 generate a new random offset for every IO. If you append eg 8 to randread, you
289 would get a new random offset for every 8 IO's. The result would be a seek for
290 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
291 that. As sequential IO is already sequential, setting \fBsequential\fR for that
292 would not result in any differences. \fBidentical\fR behaves in a similar
293 fashion, except it sends the same offset 8 number of times before generating a
298 .BI kb_base \fR=\fPint
299 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
300 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
301 reasons. Allowed values are 1024 or 1000, with 1024 being the default.
303 .BI unified_rw_reporting \fR=\fPbool
304 Fio normally reports statistics on a per data direction basis, meaning that
305 read, write, and trim are accounted and reported separately. If this option is
306 set, the fio will sum the results and report them as "mixed" instead.
308 .BI randrepeat \fR=\fPbool
309 Seed the random number generator used for random I/O patterns in a predictable
310 way so the pattern is repeatable across runs. Default: true.
312 .BI allrandrepeat \fR=\fPbool
313 Seed all random number generators in a predictable way so results are
314 repeatable across runs. Default: false.
316 .BI randseed \fR=\fPint
317 Seed the random number generators based on this seed value, to be able to
318 control what sequence of output is being generated. If not set, the random
319 sequence depends on the \fBrandrepeat\fR setting.
321 .BI use_os_rand \fR=\fPbool
322 Fio can either use the random generator supplied by the OS to generator random
323 offsets, or it can use it's own internal generator (based on Tausworthe).
324 Default is to use the internal generator, which is often of better quality and
325 faster. Default: false.
327 .BI fallocate \fR=\fPstr
328 Whether pre-allocation is performed when laying down files. Accepted values
334 Do not pre-allocate space.
337 Pre-allocate via \fBposix_fallocate\fR\|(3).
340 Pre-allocate via \fBfallocate\fR\|(2) with FALLOC_FL_KEEP_SIZE set.
343 Backward-compatible alias for 'none'.
346 Backward-compatible alias for 'posix'.
349 May not be available on all supported platforms. 'keep' is only
350 available on Linux. If using ZFS on Solaris this must be set to 'none'
351 because ZFS doesn't support it. Default: 'posix'.
354 .BI fadvise_hint \fR=\fPbool
355 Use of \fBposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
356 are likely to be issued. Default: true.
359 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
360 been transferred, unless limited by other options (\fBruntime\fR, for instance).
361 Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
362 divided between the available files for the job. If not set, fio will use the
363 full size of the given files or devices. If the files do not exist, size
364 must be given. It is also possible to give size as a percentage between 1 and
365 100. If size=20% is given, fio will use 20% of the full size of the given files
368 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
369 Sets size to something really large and waits for ENOSPC (no space left on
370 device) as the terminating condition. Only makes sense with sequential write.
371 For a read workload, the mount point will be filled first then IO started on
372 the result. This option doesn't make sense if operating on a raw device node,
373 since the size of that is already known by the file system. Additionally,
374 writing beyond end-of-device will not return ENOSPC there.
376 .BI filesize \fR=\fPirange
377 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
378 for files at random within the given range, limited to \fBsize\fR in total (if
379 that is given). If \fBfilesize\fR is not specified, each created file is the
382 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
383 Block size for I/O units. Default: 4k. Values for reads, writes, and trims
384 can be specified separately in the format \fIread\fR,\fIwrite\fR,\fItrim\fR
385 either of which may be empty to leave that value at its default. If a trailing
386 comma isn't given, the remainder will inherit the last value set.
388 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
389 Specify a range of I/O block sizes. The issued I/O unit will always be a
390 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
391 to both reads and writes if only one range is given, but can be specified
392 separately with a comma separating the values. Example: bsrange=1k-4k,2k-8k.
393 Also (see \fBblocksize\fR).
395 .BI bssplit \fR=\fPstr
396 This option allows even finer grained control of the block sizes issued,
397 not just even splits between them. With this option, you can weight various
398 block sizes for exact control of the issued IO for a job that has mixed
399 block sizes. The format of the option is bssplit=blocksize/percentage,
400 optionally adding as many definitions as needed separated by a colon.
401 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
402 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
403 splits to reads and writes. The format is identical to what the
404 \fBbs\fR option accepts, the read and write parts are separated with a
407 .B blocksize_unaligned\fR,\fP bs_unaligned
408 If set, any size in \fBblocksize_range\fR may be used. This typically won't
409 work with direct I/O, as that normally requires sector alignment.
411 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
412 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
413 the minimum blocksize given. Minimum alignment is typically 512b
414 for using direct IO, though it usually depends on the hardware block size.
415 This option is mutually exclusive with using a random map for files, so it
416 will turn off that option.
418 .BI bs_is_seq_rand \fR=\fPbool
419 If this option is set, fio will use the normal read,write blocksize settings as
420 sequential,random instead. Any random read or write will use the WRITE
421 blocksize settings, and any sequential read or write will use the READ
425 Initialise buffers with all zeros. Default: fill buffers with random data.
428 If this option is given, fio will refill the IO buffers on every submit. The
429 default is to only fill it at init time and reuse that data. Only makes sense
430 if zero_buffers isn't specified, naturally. If data verification is enabled,
431 refill_buffers is also automatically enabled.
433 .BI scramble_buffers \fR=\fPbool
434 If \fBrefill_buffers\fR is too costly and the target is using data
435 deduplication, then setting this option will slightly modify the IO buffer
436 contents to defeat normal de-dupe attempts. This is not enough to defeat
437 more clever block compression attempts, but it will stop naive dedupe
438 of blocks. Default: true.
440 .BI buffer_compress_percentage \fR=\fPint
441 If this is set, then fio will attempt to provide IO buffer content (on WRITEs)
442 that compress to the specified level. Fio does this by providing a mix of
443 random data and zeroes. Note that this is per block size unit, for file/disk
444 wide compression level that matches this setting, you'll also want to set
445 \fBrefill_buffers\fR.
447 .BI buffer_compress_chunk \fR=\fPint
448 See \fBbuffer_compress_percentage\fR. This setting allows fio to manage how
449 big the ranges of random data and zeroed data is. Without this set, fio will
450 provide \fBbuffer_compress_percentage\fR of blocksize random data, followed by
451 the remaining zeroed. With this set to some chunk size smaller than the block
452 size, fio can alternate random and zeroed data throughout the IO buffer.
454 .BI buffer_pattern \fR=\fPstr
455 If set, fio will fill the io buffers with this pattern. If not set, the contents
456 of io buffers is defined by the other options related to buffer contents. The
457 setting can be any pattern of bytes, and can be prefixed with 0x for hex
460 .BI nrfiles \fR=\fPint
461 Number of files to use for this job. Default: 1.
463 .BI openfiles \fR=\fPint
464 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
466 .BI file_service_type \fR=\fPstr
467 Defines how files to service are selected. The following types are defined:
472 Choose a file at random.
475 Round robin over open files (default).
478 Do each file in the set sequentially.
481 The number of I/Os to issue before switching a new file can be specified by
482 appending `:\fIint\fR' to the service type.
485 .BI ioengine \fR=\fPstr
486 Defines how the job issues I/O. The following types are defined:
491 Basic \fBread\fR\|(2) or \fBwrite\fR\|(2) I/O. \fBfseek\fR\|(2) is used to
492 position the I/O location.
495 Basic \fBpread\fR\|(2) or \fBpwrite\fR\|(2) I/O.
498 Basic \fBreadv\fR\|(2) or \fBwritev\fR\|(2) I/O. Will emulate queuing by
499 coalescing adjacent IOs into a single submission.
502 Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
505 Linux native asynchronous I/O. This ioengine defines engine specific options.
508 POSIX asynchronous I/O using \fBaio_read\fR\|(3) and \fBaio_write\fR\|(3).
511 Solaris native asynchronous I/O.
514 Windows native asynchronous I/O.
517 File is memory mapped with \fBmmap\fR\|(2) and data copied using
521 \fBsplice\fR\|(2) is used to transfer the data and \fBvmsplice\fR\|(2) to
522 transfer data from user-space to the kernel.
525 Use the syslet system calls to make regular read/write asynchronous.
528 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
529 the target is an sg character device, we use \fBread\fR\|(2) and
530 \fBwrite\fR\|(2) for asynchronous I/O.
533 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
534 itself and for debugging and testing purposes.
537 Transfer over the network. The protocol to be used can be defined with the
538 \fBprotocol\fR parameter. Depending on the protocol, \fBfilename\fR,
539 \fBhostname\fR, \fBport\fR, or \fBlisten\fR must be specified.
540 This ioengine defines engine specific options.
543 Like \fBnet\fR, but uses \fBsplice\fR\|(2) and \fBvmsplice\fR\|(2) to map data
544 and send/receive. This ioengine defines engine specific options.
547 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
548 \fBcpucycles\fR parameters.
551 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
552 approach to asynchronous I/O.
554 See <http://www.xmailserver.org/guasi\-lib.html>.
557 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
558 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
561 Loads an external I/O engine object file. Append the engine filename as
565 IO engine that does regular linux native fallocate call to simulate data
566 transfer as fio ioengine
568 DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
570 DIR_WRITE does fallocate(,mode = 0)
572 DDIR_TRIM does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)
575 IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
576 request to DDIR_WRITE event
579 IO engine supporting direct access to Ceph Rados Block Devices (RBD) via librbd
580 without the need to use the kernel rbd driver. This ioengine defines engine specific
586 .BI iodepth \fR=\fPint
587 Number of I/O units to keep in flight against the file. Note that increasing
588 iodepth beyond 1 will not affect synchronous ioengines (except for small
589 degress when verify_async is in use). Even async engines my impose OS
590 restrictions causing the desired depth not to be achieved. This may happen on
591 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
592 not async on that OS. Keep an eye on the IO depth distribution in the
593 fio output to verify that the achieved depth is as expected. Default: 1.
595 .BI iodepth_batch \fR=\fPint
596 Number of I/Os to submit at once. Default: \fBiodepth\fR.
598 .BI iodepth_batch_complete \fR=\fPint
599 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
600 means that we'll ask for a minimum of 1 IO in the retrieval process from the
601 kernel. The IO retrieval will go on until we hit the limit set by
602 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
603 completed events before queuing more IO. This helps reduce IO latency, at the
604 cost of more retrieval system calls.
606 .BI iodepth_low \fR=\fPint
607 Low watermark indicating when to start filling the queue again. Default:
610 .BI direct \fR=\fPbool
611 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
613 .BI atomic \fR=\fPbool
614 If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
615 to be stable once acknowledged by the operating system. Only Linux supports
618 .BI buffered \fR=\fPbool
619 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
622 .BI offset \fR=\fPint
623 Offset in the file to start I/O. Data before the offset will not be touched.
625 .BI offset_increment \fR=\fPint
626 If this is provided, then the real offset becomes the
627 offset + offset_increment * thread_number, where the thread number is a counter
628 that starts at 0 and is incremented for each job. This option is useful if
629 there are several jobs which are intended to operate on a file in parallel in
630 disjoint segments, with even spacing between the starting points.
632 .BI number_ios \fR=\fPint
633 Fio will normally perform IOs until it has exhausted the size of the region
634 set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
635 condition). With this setting, the range/size can be set independently of
636 the number of IOs to perform. When fio reaches this number, it will exit
637 normally and report status.
640 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
641 0, don't sync. Default: 0.
643 .BI fdatasync \fR=\fPint
644 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
645 data parts of the file. Default: 0.
647 .BI write_barrier \fR=\fPint
648 Make every Nth write a barrier write.
650 .BI sync_file_range \fR=\fPstr:int
651 Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
652 track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
653 \fRstr\fP can currently be one or more of:
657 SYNC_FILE_RANGE_WAIT_BEFORE
660 SYNC_FILE_RANGE_WRITE
663 SYNC_FILE_RANGE_WRITE
667 So if you do sync_file_range=wait_before,write:8, fio would use
668 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
669 Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
671 .BI overwrite \fR=\fPbool
672 If writing, setup the file first and do overwrites. Default: false.
674 .BI end_fsync \fR=\fPbool
675 Sync file contents when a write stage has completed. Default: false.
677 .BI fsync_on_close \fR=\fPbool
678 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
679 it will happen on every close, not just at the end of the job. Default: false.
681 .BI rwmixread \fR=\fPint
682 Percentage of a mixed workload that should be reads. Default: 50.
684 .BI rwmixwrite \fR=\fPint
685 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
686 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
687 overrides the first. This may interfere with a given rate setting, if fio is
688 asked to limit reads or writes to a certain rate. If that is the case, then
689 the distribution may be skewed. Default: 50.
691 .BI random_distribution \fR=\fPstr:float
692 By default, fio will use a completely uniform random distribution when asked
693 to perform random IO. Sometimes it is useful to skew the distribution in
694 specific ways, ensuring that some parts of the data is more hot than others.
695 Fio includes the following distribution models:
699 Uniform random distribution
709 When using a zipf or pareto distribution, an input value is also needed to
710 define the access pattern. For zipf, this is the zipf theta. For pareto,
711 it's the pareto power. Fio includes a test program, genzipf, that can be
712 used visualize what the given input values will yield in terms of hit rates.
713 If you wanted to use zipf with a theta of 1.2, you would use
714 random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
715 fio will disable use of the random map.
717 .BI percentage_random \fR=\fPint
718 For a random workload, set how big a percentage should be random. This defaults
719 to 100%, in which case the workload is fully random. It can be set from
720 anywhere from 0 to 100. Setting it to 0 would make the workload fully
721 sequential. It is possible to set different values for reads, writes, and
722 trim. To do so, simply use a comma separated list. See \fBblocksize\fR.
725 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
726 this parameter is given, a new offset will be chosen without looking at past
727 I/O history. This parameter is mutually exclusive with \fBverify\fR.
729 .BI softrandommap \fR=\fPbool
730 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
731 fails to allocate the map, if this option is set it will continue without a
732 random block map. As coverage will not be as complete as with random maps, this
733 option is disabled by default.
735 .BI random_generator \fR=\fPstr
736 Fio supports the following engines for generating IO offsets for random IO:
740 Strong 2^88 cycle random number generator
743 Linear feedback shift register generator
747 Tausworthe is a strong random number generator, but it requires tracking on the
748 side if we want to ensure that blocks are only read or written once. LFSR
749 guarantees that we never generate the same offset twice, and it's also less
750 computationally expensive. It's not a true random generator, however, though
751 for IO purposes it's typically good enough. LFSR only works with single block
752 sizes, not with workloads that use multiple block sizes. If used with such a
753 workload, fio may read or write some blocks multiple times.
756 Run job with given nice value. See \fBnice\fR\|(2).
759 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
762 .BI prioclass \fR=\fPint
763 Set I/O priority class. See \fBionice\fR\|(1).
765 .BI thinktime \fR=\fPint
766 Stall job for given number of microseconds between issuing I/Os.
768 .BI thinktime_spin \fR=\fPint
769 Pretend to spend CPU time for given number of microseconds, sleeping the rest
770 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
772 .BI thinktime_blocks \fR=\fPint
773 Only valid if thinktime is set - control how many blocks to issue, before
774 waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
775 make fio wait \fBthinktime\fR microseconds after every block. This
776 effectively makes any queue depth setting redundant, since no more than 1 IO
777 will be queued before we have to complete it and do our thinktime. In other
778 words, this setting effectively caps the queue depth if the latter is larger.
782 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
783 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
784 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
785 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
786 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
787 limit writes (to 500KB/sec), the latter will only limit reads.
789 .BI ratemin \fR=\fPint
790 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
791 Failing to meet this requirement will cause the job to exit. The same format
792 as \fBrate\fR is used for read vs write separation.
794 .BI rate_iops \fR=\fPint
795 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
796 specified independently of bandwidth. The same format as \fBrate\fR is used for
797 read vs write separation. If \fBblocksize\fR is a range, the smallest block
798 size is used as the metric.
800 .BI rate_iops_min \fR=\fPint
801 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
802 is used for read vs write separation.
804 .BI ratecycle \fR=\fPint
805 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
806 milliseconds. Default: 1000ms.
808 .BI latency_target \fR=\fPint
809 If set, fio will attempt to find the max performance point that the given
810 workload will run at while maintaining a latency below this target. The
811 values is given in microseconds. See \fBlatency_window\fR and
812 \fBlatency_percentile\fR.
814 .BI latency_window \fR=\fPint
815 Used with \fBlatency_target\fR to specify the sample window that the job
816 is run at varying queue depths to test the performance. The value is given
819 .BI latency_percentile \fR=\fPfloat
820 The percentage of IOs that must fall within the criteria specified by
821 \fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
822 to 100.0, meaning that all IOs must be equal or below to the value set
823 by \fBlatency_target\fR.
825 .BI max_latency \fR=\fPint
826 If set, fio will exit the job if it exceeds this maximum latency. It will exit
829 .BI cpumask \fR=\fPint
830 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
831 may run on. See \fBsched_setaffinity\fR\|(2).
833 .BI cpus_allowed \fR=\fPstr
834 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
836 .BI numa_cpu_nodes \fR=\fPstr
837 Set this job running on specified NUMA nodes' CPUs. The arguments allow
838 comma delimited list of cpu numbers, A-B ranges, or 'all'.
840 .BI numa_mem_policy \fR=\fPstr
841 Set this job's memory policy and corresponding NUMA nodes. Format of
845 .B <mode>[:<nodelist>]
848 is one of the following memory policy:
850 .B default, prefer, bind, interleave, local
853 For \fBdefault\fR and \fBlocal\fR memory policy, no \fBnodelist\fR is
854 needed to be specified. For \fBprefer\fR, only one node is
855 allowed. For \fBbind\fR and \fBinterleave\fR, \fBnodelist\fR allows
856 comma delimited list of numbers, A-B ranges, or 'all'.
858 .BI startdelay \fR=\fPirange
859 Delay start of job for the specified number of seconds. Supports all time
860 suffixes to allow specification of hours, minutes, seconds and
861 milliseconds - seconds are the default if a unit is ommited.
862 Can be given as a range which causes each thread to choose randomly out of the
865 .BI runtime \fR=\fPint
866 Terminate processing after the specified number of seconds.
869 If given, run for the specified \fBruntime\fR duration even if the files are
870 completely read or written. The same workload will be repeated as many times
871 as \fBruntime\fR allows.
873 .BI ramp_time \fR=\fPint
874 If set, fio will run the specified workload for this amount of time before
875 logging any performance numbers. Useful for letting performance settle before
876 logging results, thus minimizing the runtime required for stable results. Note
877 that the \fBramp_time\fR is considered lead in time for a job, thus it will
878 increase the total runtime if a special timeout or runtime is specified.
880 .BI invalidate \fR=\fPbool
881 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
884 Use synchronous I/O for buffered writes. For the majority of I/O engines,
885 this means using O_SYNC. Default: false.
887 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
888 Allocation method for I/O unit buffer. Allowed values are:
893 Allocate memory with \fBmalloc\fR\|(3).
896 Use shared memory buffers allocated through \fBshmget\fR\|(2).
899 Same as \fBshm\fR, but use huge pages as backing.
902 Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
903 is given after the option in the format `:\fIfile\fR'.
906 Same as \fBmmap\fR, but use huge files as backing.
909 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
910 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
911 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
912 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
913 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
914 and the documentation for that. Normally you just need to echo an appropriate
915 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
919 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
920 This indicates the memory alignment of the IO memory buffers. Note that the
921 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
922 the alignment of the following buffers are given by the \fBbs\fR used. In
923 other words, if using a \fBbs\fR that is a multiple of the page sized in the
924 system, all buffers will be aligned to this value. If using a \fBbs\fR that
925 is not page aligned, the alignment of subsequent IO memory buffers is the
926 sum of the \fBiomem_align\fR and \fBbs\fR used.
928 .BI hugepage\-size \fR=\fPint
929 Defines the size of a huge page. Must be at least equal to the system setting.
930 Should be a multiple of 1MB. Default: 4MB.
933 Terminate all jobs when one finishes. Default: wait for each job to finish.
935 .BI bwavgtime \fR=\fPint
936 Average bandwidth calculations over the given time in milliseconds. Default:
939 .BI iopsavgtime \fR=\fPint
940 Average IOPS calculations over the given time in milliseconds. Default:
943 .BI create_serialize \fR=\fPbool
944 If true, serialize file creation for the jobs. Default: true.
946 .BI create_fsync \fR=\fPbool
947 \fBfsync\fR\|(2) data file after creation. Default: true.
949 .BI create_on_open \fR=\fPbool
950 If true, the files are not created until they are opened for IO by the job.
952 .BI create_only \fR=\fPbool
953 If true, fio will only run the setup phase of the job. If files need to be
954 laid out or updated on disk, only that will be done. The actual job contents
957 .BI pre_read \fR=\fPbool
958 If this is given, files will be pre-read into memory before starting the given
959 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
960 pointless to pre-read and then drop the cache. This will only work for IO
961 engines that are seekable, since they allow you to read the same data
962 multiple times. Thus it will not work on eg network or splice IO.
964 .BI unlink \fR=\fPbool
965 Unlink job files when done. Default: false.
968 Specifies the number of iterations (runs of the same workload) of this job.
971 .BI verify_only \fR=\fPbool
972 Do not perform the specified workload, only verify data still matches previous
973 invocation of this workload. This option allows one to check data multiple
974 times at a later date without overwriting it. This option makes sense only for
975 workloads that write data, and does not support workloads with the
976 \fBtime_based\fR option set.
978 .BI do_verify \fR=\fPbool
979 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
982 .BI verify \fR=\fPstr
983 Method of verifying file contents after each iteration of the job. Allowed
988 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1
989 Store appropriate checksum in the header of each block. crc32c-intel is
990 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
991 not supported by the system.
994 Write extra information about each I/O (timestamp, block number, etc.). The
995 block number is verified. See \fBverify_pattern\fR as well.
998 Pretend to verify. Used for testing internals.
1001 This option can be used for repeated burn-in tests of a system to make sure
1002 that the written data is also correctly read back. If the data direction given
1003 is a read or random read, fio will assume that it should verify a previously
1004 written file. If the data direction includes any form of write, the verify will
1005 be of the newly written data.
1008 .BI verifysort \fR=\fPbool
1009 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
1010 read them back in a sorted manner. Default: true.
1012 .BI verifysort_nr \fR=\fPint
1013 Pre-load and sort verify blocks for a read workload.
1015 .BI verify_offset \fR=\fPint
1016 Swap the verification header with data somewhere else in the block before
1017 writing. It is swapped back before verifying.
1019 .BI verify_interval \fR=\fPint
1020 Write the verification header for this number of bytes, which should divide
1021 \fBblocksize\fR. Default: \fBblocksize\fR.
1023 .BI verify_pattern \fR=\fPstr
1024 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
1025 with totally random bytes, but sometimes it's interesting to fill with a known
1026 pattern for io verification purposes. Depending on the width of the pattern,
1027 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
1028 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
1029 has to be a hex number that starts with either "0x" or "0X". Use with
1032 .BI verify_fatal \fR=\fPbool
1033 If true, exit the job on the first observed verification failure. Default:
1036 .BI verify_dump \fR=\fPbool
1037 If set, dump the contents of both the original data block and the data block we
1038 read off disk to files. This allows later analysis to inspect just what kind of
1039 data corruption occurred. Off by default.
1041 .BI verify_async \fR=\fPint
1042 Fio will normally verify IO inline from the submitting thread. This option
1043 takes an integer describing how many async offload threads to create for IO
1044 verification instead, causing fio to offload the duty of verifying IO contents
1045 to one or more separate threads. If using this offload option, even sync IO
1046 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
1047 allows them to have IO in flight while verifies are running.
1049 .BI verify_async_cpus \fR=\fPstr
1050 Tell fio to set the given CPU affinity on the async IO verification threads.
1051 See \fBcpus_allowed\fP for the format used.
1053 .BI verify_backlog \fR=\fPint
1054 Fio will normally verify the written contents of a job that utilizes verify
1055 once that job has completed. In other words, everything is written then
1056 everything is read back and verified. You may want to verify continually
1057 instead for a variety of reasons. Fio stores the meta data associated with an
1058 IO block in memory, so for large verify workloads, quite a bit of memory would
1059 be used up holding this meta data. If this option is enabled, fio will write
1060 only N blocks before verifying these blocks.
1062 .BI verify_backlog_batch \fR=\fPint
1063 Control how many blocks fio will verify if verify_backlog is set. If not set,
1064 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
1065 read back and verified). If \fBverify_backlog_batch\fR is less than
1066 \fBverify_backlog\fR then not all blocks will be verified, if
1067 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
1068 will be verified more than once.
1070 .BI trim_percentage \fR=\fPint
1071 Number of verify blocks to discard/trim.
1073 .BI trim_verify_zero \fR=\fPbool
1074 Verify that trim/discarded blocks are returned as zeroes.
1076 .BI trim_backlog \fR=\fPint
1077 Trim after this number of blocks are written.
1079 .BI trim_backlog_batch \fR=\fPint
1080 Trim this number of IO blocks.
1082 .BI experimental_verify \fR=\fPbool
1083 Enable experimental verification.
1085 .B stonewall "\fR,\fP wait_for_previous"
1086 Wait for preceding jobs in the job file to exit before starting this one.
1087 \fBstonewall\fR implies \fBnew_group\fR.
1090 Start a new reporting group. If not given, all jobs in a file will be part
1091 of the same reporting group, unless separated by a stonewall.
1093 .BI numjobs \fR=\fPint
1094 Number of clones (processes/threads performing the same workload) of this job.
1098 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
1102 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
1103 with \fBfork\fR\|(2).
1105 .BI zonesize \fR=\fPint
1106 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
1108 .BI zonerange \fR=\fPint
1109 Give size of an IO zone. See \fBzoneskip\fR.
1111 .BI zoneskip \fR=\fPint
1112 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
1115 .BI write_iolog \fR=\fPstr
1116 Write the issued I/O patterns to the specified file. Specify a separate file
1117 for each job, otherwise the iologs will be interspersed and the file may be
1120 .BI read_iolog \fR=\fPstr
1121 Replay the I/O patterns contained in the specified file generated by
1122 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
1124 .BI replay_no_stall \fR=\fPint
1125 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1126 attempts to respect timing information between I/Os. Enabling
1127 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
1128 still respecting ordering.
1130 .BI replay_redirect \fR=\fPstr
1131 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1132 is to replay the IOPS onto the major/minor device that each IOP was recorded
1133 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
1134 single specified device regardless of the device it was recorded from.
1136 .BI write_bw_log \fR=\fPstr
1137 If given, write a bandwidth log of the jobs in this job file. Can be used to
1138 store data of the bandwidth of the jobs in their lifetime. The included
1139 fio_generate_plots script uses gnuplot to turn these text files into nice
1140 graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
1141 option, the postfix is _bw.log.
1143 .BI write_lat_log \fR=\fPstr
1144 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
1145 filename is given with this option, the default filename of "jobname_type.log"
1146 is used. Even if the filename is given, fio will still append the type of log.
1148 .BI write_iops_log \fR=\fPstr
1149 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
1150 option, the default filename of "jobname_type.log" is used. Even if the
1151 filename is given, fio will still append the type of log.
1153 .BI log_avg_msec \fR=\fPint
1154 By default, fio will log an entry in the iops, latency, or bw log for every
1155 IO that completes. When writing to the disk log, that can quickly grow to a
1156 very large size. Setting this option makes fio average the each log entry
1157 over the specified period of time, reducing the resolution of the log.
1160 .BI disable_lat \fR=\fPbool
1161 Disable measurements of total latency numbers. Useful only for cutting
1162 back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
1163 really high IOPS rates. Note that to really get rid of a large amount of these
1164 calls, this option must be used with disable_slat and disable_bw as well.
1166 .BI disable_clat \fR=\fPbool
1167 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
1169 .BI disable_slat \fR=\fPbool
1170 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
1172 .BI disable_bw_measurement \fR=\fPbool
1173 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
1175 .BI lockmem \fR=\fPint
1176 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
1177 simulate a smaller amount of memory. The amount specified is per worker.
1179 .BI exec_prerun \fR=\fPstr
1180 Before running the job, execute the specified command with \fBsystem\fR\|(3).
1182 Output is redirected in a file called \fBjobname.prerun.txt\fR
1185 .BI exec_postrun \fR=\fPstr
1186 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
1188 Output is redirected in a file called \fBjobname.postrun.txt\fR
1191 .BI ioscheduler \fR=\fPstr
1192 Attempt to switch the device hosting the file to the specified I/O scheduler.
1194 .BI cpuload \fR=\fPint
1195 If the job is a CPU cycle-eater, attempt to use the specified percentage of
1198 .BI cpuchunks \fR=\fPint
1199 If the job is a CPU cycle-eater, split the load into cycles of the
1200 given time in milliseconds.
1202 .BI disk_util \fR=\fPbool
1203 Generate disk utilization statistics if the platform supports it. Default: true.
1205 .BI clocksource \fR=\fPstr
1206 Use the given clocksource as the base of timing. The supported options are:
1210 \fBgettimeofday\fR\|(2)
1213 \fBclock_gettime\fR\|(2)
1216 Internal CPU clock source
1220 \fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
1221 (and fio is heavy on time calls). Fio will automatically use this clocksource
1222 if it's supported and considered reliable on the system it is running on,
1223 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
1224 means supporting TSC Invariant.
1226 .BI gtod_reduce \fR=\fPbool
1227 Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
1228 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
1229 \fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
1230 the gtod() calls we would have done if all time keeping was enabled.
1232 .BI gtod_cpu \fR=\fPint
1233 Sometimes it's cheaper to dedicate a single thread of execution to just getting
1234 the current time. Fio (and databases, for instance) are very intensive on
1235 \fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
1236 nothing but logging current time to a shared memory location. Then the other
1237 threads/processes that run IO workloads need only copy that segment, instead of
1238 entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
1239 these time calls will be excluded from other uses. Fio will manually clear it
1240 from the CPU mask of other jobs.
1242 .BI ignore_error \fR=\fPstr
1243 Sometimes you want to ignore some errors during test in that case you can specify
1244 error list for each error type.
1246 ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
1248 errors for given error type is separated with ':'.
1249 Error may be symbol ('ENOSPC', 'ENOMEM') or an integer.
1251 Example: ignore_error=EAGAIN,ENOSPC:122 .
1253 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from WRITE.
1255 .BI error_dump \fR=\fPbool
1256 If set dump every error even if it is non fatal, true by default. If disabled
1257 only fatal error will be dumped
1259 .BI profile \fR=\fPstr
1260 Select a specific builtin performance test.
1262 .BI cgroup \fR=\fPstr
1263 Add job to this control group. If it doesn't exist, it will be created.
1264 The system must have a mounted cgroup blkio mount point for this to work. If
1265 your system doesn't have it mounted, you can do so with:
1267 # mount \-t cgroup \-o blkio none /cgroup
1269 .BI cgroup_weight \fR=\fPint
1270 Set the weight of the cgroup to this value. See the documentation that comes
1271 with the kernel, allowed values are in the range of 100..1000.
1273 .BI cgroup_nodelete \fR=\fPbool
1274 Normally fio will delete the cgroups it has created after the job completion.
1275 To override this behavior and to leave cgroups around after the job completion,
1276 set cgroup_nodelete=1. This can be useful if one wants to inspect various
1277 cgroup files after job completion. Default: false
1280 Instead of running as the invoking user, set the user ID to this value before
1281 the thread/process does any work.
1284 Set group ID, see \fBuid\fR.
1286 .BI unit_base \fR=\fPint
1287 Base unit for reporting. Allowed values are:
1291 Use auto-detection (default).
1301 .BI flow_id \fR=\fPint
1302 The ID of the flow. If not specified, it defaults to being a global flow. See
1306 Weight in token-based flow control. If this value is used, then there is a
1307 \fBflow counter\fR which is used to regulate the proportion of activity between
1308 two or more jobs. fio attempts to keep this flow counter near zero. The
1309 \fBflow\fR parameter stands for how much should be added or subtracted to the
1310 flow counter on each iteration of the main I/O loop. That is, if one job has
1311 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
1312 1:8 ratio in how much one runs vs the other.
1314 .BI flow_watermark \fR=\fPint
1315 The maximum value that the absolute value of the flow counter is allowed to
1316 reach before the job must wait for a lower value of the counter.
1318 .BI flow_sleep \fR=\fPint
1319 The period of time, in microseconds, to wait after the flow watermark has been
1320 exceeded before retrying operations
1322 .BI clat_percentiles \fR=\fPbool
1323 Enable the reporting of percentiles of completion latencies.
1325 .BI percentile_list \fR=\fPfloat_list
1326 Overwrite the default list of percentiles for completion
1327 latencies. Each number is a floating number in the range (0,100], and
1328 the maximum length of the list is 20. Use ':' to separate the
1329 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1330 report the values of completion latency below which 99.5% and 99.9% of
1331 the observed latencies fell, respectively.
1332 .SS "Ioengine Parameters List"
1333 Some parameters are only valid when a specific ioengine is in use. These are
1334 used identically to normal parameters, with the caveat that when used on the
1335 command line, the must come after the ioengine that defines them is selected.
1337 .BI (cpu)cpuload \fR=\fPint
1338 Attempt to use the specified percentage of CPU cycles.
1340 .BI (cpu)cpuchunks \fR=\fPint
1341 Split the load into cycles of the given time. In microseconds.
1343 .BI (libaio)userspace_reap
1344 Normally, with the libaio engine in use, fio will use
1345 the io_getevents system call to reap newly returned events.
1346 With this flag turned on, the AIO ring will be read directly
1347 from user-space to reap events. The reaping mode is only
1348 enabled when polling for a minimum of 0 events (eg when
1349 iodepth_batch_complete=0).
1351 .BI (net,netsplice)hostname \fR=\fPstr
1352 The host name or IP address to use for TCP or UDP based IO.
1353 If the job is a TCP listener or UDP reader, the hostname is not
1354 used and must be omitted unless it is a valid UDP multicast address.
1356 .BI (net,netsplice)port \fR=\fPint
1357 The TCP or UDP port to bind to or connect to.
1359 .BI (net,netsplice)interface \fR=\fPstr
1360 The IP address of the network interface used to send or receive UDP multicast
1363 .BI (net,netsplice)ttl \fR=\fPint
1364 Time-to-live value for outgoing UDP multicast packets. Default: 1
1366 .BI (net,netsplice)nodelay \fR=\fPbool
1367 Set TCP_NODELAY on TCP connections.
1369 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1370 The network protocol to use. Accepted values are:
1375 Transmission control protocol
1378 Transmission control protocol V6
1381 User datagram protocol
1384 User datagram protocol V6
1390 When the protocol is TCP or UDP, the port must also be given,
1391 as well as the hostname if the job is a TCP listener or UDP
1392 reader. For unix sockets, the normal filename option should be
1393 used and the port is invalid.
1396 .BI (net,netsplice)listen
1397 For TCP network connections, tell fio to listen for incoming
1398 connections rather than initiating an outgoing connection. The
1399 hostname must be omitted if this option is used.
1401 .BI (net, pingpong) \fR=\fPbool
1402 Normally a network writer will just continue writing data, and a network reader
1403 will just consume packages. If pingpong=1 is set, a writer will send its normal
1404 payload to the reader, then wait for the reader to send the same payload back.
1405 This allows fio to measure network latencies. The submission and completion
1406 latencies then measure local time spent sending or receiving, and the
1407 completion latency measures how long it took for the other end to receive and
1408 send back. For UDP multicast traffic pingpong=1 should only be set for a single
1409 reader when multiple readers are listening to the same address.
1411 .BI (e4defrag,donorname) \fR=\fPstr
1412 File will be used as a block donor (swap extents between files)
1414 .BI (e4defrag,inplace) \fR=\fPint
1415 Configure donor file block allocation strategy
1418 Preallocate donor's file on init
1421 allocate space immediately inside defragment event, and free right after event
1424 .BI (rbd)rbdname \fR=\fPstr
1425 Specifies the name of the RBD.
1427 .BI (rbd)pool \fR=\fPstr
1428 Specifies the name of the Ceph pool containing the RBD.
1430 .BI (rbd)clientname \fR=\fPstr
1431 Specifies the username (without the 'client.' prefix) used to access the Ceph cluster.
1433 While running, \fBfio\fR will display the status of the created jobs. For
1437 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1440 The characters in the first set of brackets denote the current status of each
1441 threads. The possible values are:
1447 Setup but not started.
1453 Initialized, waiting.
1456 Running, doing sequential reads.
1459 Running, doing random reads.
1462 Running, doing sequential writes.
1465 Running, doing random writes.
1468 Running, doing mixed sequential reads/writes.
1471 Running, doing mixed random reads/writes.
1474 Running, currently waiting for \fBfsync\fR\|(2).
1477 Running, verifying written data.
1480 Exited, not reaped by main thread.
1483 Exited, thread reaped.
1487 The second set of brackets shows the estimated completion percentage of
1488 the current group. The third set shows the read and write I/O rate,
1489 respectively. Finally, the estimated run time of the job is displayed.
1491 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1492 for each thread, each group of threads, and each disk, in that order.
1494 Per-thread statistics first show the threads client number, group-id, and
1495 error code. The remaining figures are as follows:
1499 Number of megabytes of I/O performed.
1502 Average data rate (bandwidth).
1508 Submission latency minimum, maximum, average and standard deviation. This is
1509 the time it took to submit the I/O.
1512 Completion latency minimum, maximum, average and standard deviation. This
1513 is the time between submission and completion.
1516 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1517 and standard deviation.
1520 CPU usage statistics. Includes user and system time, number of context switches
1521 this thread went through and number of major and minor page faults.
1524 Distribution of I/O depths. Each depth includes everything less than (or equal)
1525 to it, but greater than the previous depth.
1528 Number of read/write requests issued, and number of short read/write requests.
1531 Distribution of I/O completion latencies. The numbers follow the same pattern
1535 The group statistics show:
1540 Number of megabytes I/O performed.
1543 Aggregate bandwidth of threads in the group.
1546 Minimum average bandwidth a thread saw.
1549 Maximum average bandwidth a thread saw.
1552 Shortest runtime of threads in the group.
1555 Longest runtime of threads in the group.
1559 Finally, disk statistics are printed with reads first:
1564 Number of I/Os performed by all groups.
1567 Number of merges in the I/O scheduler.
1570 Number of ticks we kept the disk busy.
1573 Total time spent in the disk queue.
1580 It is also possible to get fio to dump the current output while it is
1581 running, without terminating the job. To do that, send fio the \fBUSR1\fR
1584 If the \fB\-\-minimal\fR / \fB\-\-append-terse\fR options are given, the
1585 results will be printed/appended in a semicolon-delimited format suitable for
1587 A job description (if provided) follows on a new line. Note that the first
1588 number in the line is the version number. If the output has to be changed
1589 for some reason, this number will be incremented by 1 to signify that
1590 change. The fields are:
1593 .B terse version, fio version, jobname, groupid, error
1597 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1601 .B min, max, mean, standard deviation
1605 .B min, max, mean, standard deviation
1607 Completion latency percentiles (20 fields):
1609 .B Xth percentile=usec
1613 .B min, max, mean, standard deviation
1617 .B min, max, aggregate percentage of total, mean, standard deviation
1623 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1627 .B min, max, mean, standard deviation
1631 .B min, max, mean, standard deviation
1633 Completion latency percentiles (20 fields):
1635 .B Xth percentile=usec
1639 .B min, max, mean, standard deviation
1643 .B min, max, aggregate percentage of total, mean, standard deviation
1649 .B user, system, context switches, major page faults, minor page faults
1652 IO depth distribution:
1654 .B <=1, 2, 4, 8, 16, 32, >=64
1657 IO latency distribution:
1661 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1665 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1669 Disk utilization (1 for each disk used):
1671 .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
1674 Error Info (dependent on continue_on_error, default off):
1676 .B total # errors, first error code
1679 .B text description (if provided in config - appears on newline)
1682 Normally you would run fio as a stand-alone application on the machine
1683 where the IO workload should be generated. However, it is also possible to
1684 run the frontend and backend of fio separately. This makes it possible to
1685 have a fio server running on the machine(s) where the IO workload should
1686 be running, while controlling it from another machine.
1688 To start the server, you would do:
1690 \fBfio \-\-server=args\fR
1692 on that machine, where args defines what fio listens to. The arguments
1693 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1694 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain
1695 socket. 'hostname' is either a hostname or IP address, and 'port' is the port to
1696 listen to (only valid for TCP/IP, not a local socket). Some examples:
1700 Start a fio server, listening on all interfaces on the default port (8765).
1702 2) fio \-\-server=ip:hostname,4444
1704 Start a fio server, listening on IP belonging to hostname and on port 4444.
1706 3) fio \-\-server=ip6:::1,4444
1708 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1710 4) fio \-\-server=,4444
1712 Start a fio server, listening on all interfaces on port 4444.
1714 5) fio \-\-server=1.2.3.4
1716 Start a fio server, listening on IP 1.2.3.4 on the default port.
1718 6) fio \-\-server=sock:/tmp/fio.sock
1720 Start a fio server, listening on the local socket /tmp/fio.sock.
1722 When a server is running, you can connect to it from a client. The client
1725 fio \-\-local-args \-\-client=server \-\-remote-args <job file(s)>
1727 where \-\-local-args are arguments that are local to the client where it is
1728 running, 'server' is the connect string, and \-\-remote-args and <job file(s)>
1729 are sent to the server. The 'server' string follows the same format as it
1730 does on the server side, to allow IP/hostname/socket and port strings.
1731 You can connect to multiple clients as well, to do that you could run:
1733 fio \-\-client=server2 \-\-client=server2 <job file(s)>
1737 was written by Jens Axboe <jens.axboe@oracle.com>,
1738 now Jens Axboe <jaxboe@fusionio.com>.
1740 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1741 on documentation by Jens Axboe.
1742 .SH "REPORTING BUGS"
1743 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1746 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1748 Sample jobfiles are available in the \fBexamples\fR directory.
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