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. This option can be used multiple times to add 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' (or msec) milli seconds, 'us' (or 'usec') micro
135 seconds. Time values without a unit specify seconds.
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. See
170 \fIfilename\fR for considerations regarding escaping certain characters on
173 .BI filename \fR=\fPstr
175 normally makes up a file name based on the job name, thread number, and file
176 number. If you want to share files between threads in a job or several jobs,
177 specify a \fIfilename\fR for each of them to override the default.
178 If the I/O engine is file-based, you can specify
179 a number of files by separating the names with a `:' character. `\-' is a
180 reserved name, meaning stdin or stdout, depending on the read/write direction
181 set. On Windows, disk devices are accessed as \\.\PhysicalDrive0 for the first
182 device, \\.\PhysicalDrive1 for the second etc. Note: Windows and FreeBSD
183 prevent write access to areas of the disk containing in-use data
184 (e.g. filesystems). If the wanted filename does need to include a colon, then
185 escape that with a '\\' character. For instance, if the filename is
186 "/dev/dsk/foo@3,0:c", then you would use filename="/dev/dsk/foo@3,0\\:c".
188 .BI filename_format \fR=\fPstr
189 If sharing multiple files between jobs, it is usually necessary to have
190 fio generate the exact names that you want. By default, fio will name a file
191 based on the default file format specification of
192 \fBjobname.jobnumber.filenumber\fP. With this option, that can be
193 customized. Fio will recognize and replace the following keywords in this
199 The name of the worker thread or process.
202 The incremental number of the worker thread or process.
205 The incremental number of the file for that worker thread or process.
208 To have dependent jobs share a set of files, this option can be set to
209 have fio generate filenames that are shared between the two. For instance,
210 if \fBtestfiles.$filenum\fR is specified, file number 4 for any job will
211 be named \fBtestfiles.4\fR. The default of \fB$jobname.$jobnum.$filenum\fR
212 will be used if no other format specifier is given.
216 .BI lockfile \fR=\fPstr
217 Fio defaults to not locking any files before it does IO to them. If a file or
218 file descriptor is shared, fio can serialize IO to that file to make the end
219 result consistent. This is usual for emulating real workloads that share files.
225 No locking. This is the default.
228 Only one thread or process may do IO at a time, excluding all others.
231 Read-write locking on the file. Many readers may access the file at the same
232 time, but writes get exclusive access.
236 .BI opendir \fR=\fPstr
237 Recursively open any files below directory \fIstr\fR.
239 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
240 Type of I/O pattern. Accepted values are:
251 Sequential trim (Linux block devices only).
260 Random trim (Linux block devices only).
263 Mixed sequential reads and writes.
266 Mixed random reads and writes.
269 For mixed I/O, the default split is 50/50. For certain types of io the result
270 may still be skewed a bit, since the speed may be different. It is possible to
271 specify a number of IO's to do before getting a new offset, this is done by
272 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
273 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
274 value of 8. If the postfix is used with a sequential IO pattern, then the value
275 specified will be added to the generated offset for each IO. For instance,
276 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
277 into sequential IO with holes. See the \fBrw_sequencer\fR option.
280 .BI rw_sequencer \fR=\fPstr
281 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
282 then this option controls how that number modifies the IO offset being
283 generated. Accepted values are:
288 Generate sequential offset
291 Generate the same offset
294 \fBsequential\fR is only useful for random IO, where fio would normally
295 generate a new random offset for every IO. If you append eg 8 to randread, you
296 would get a new random offset for every 8 IO's. The result would be a seek for
297 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
298 that. As sequential IO is already sequential, setting \fBsequential\fR for that
299 would not result in any differences. \fBidentical\fR behaves in a similar
300 fashion, except it sends the same offset 8 number of times before generating a
305 .BI kb_base \fR=\fPint
306 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
307 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
308 reasons. Allowed values are 1024 or 1000, with 1024 being the default.
310 .BI unified_rw_reporting \fR=\fPbool
311 Fio normally reports statistics on a per data direction basis, meaning that
312 read, write, and trim are accounted and reported separately. If this option is
313 set fio sums the results and reports them as "mixed" instead.
315 .BI randrepeat \fR=\fPbool
316 Seed the random number generator used for random I/O patterns in a predictable
317 way so the pattern is repeatable across runs. Default: true.
319 .BI allrandrepeat \fR=\fPbool
320 Seed all random number generators in a predictable way so results are
321 repeatable across runs. Default: false.
323 .BI randseed \fR=\fPint
324 Seed the random number generators based on this seed value, to be able to
325 control what sequence of output is being generated. If not set, the random
326 sequence depends on the \fBrandrepeat\fR setting.
328 .BI use_os_rand \fR=\fPbool
329 Fio can either use the random generator supplied by the OS to generate random
330 offsets, or it can use its own internal generator (based on Tausworthe).
331 Default is to use the internal generator, which is often of better quality and
332 faster. Default: false.
334 .BI fallocate \fR=\fPstr
335 Whether pre-allocation is performed when laying down files. Accepted values
341 Do not pre-allocate space.
344 Pre-allocate via \fBposix_fallocate\fR\|(3).
347 Pre-allocate via \fBfallocate\fR\|(2) with FALLOC_FL_KEEP_SIZE set.
350 Backward-compatible alias for 'none'.
353 Backward-compatible alias for 'posix'.
356 May not be available on all supported platforms. 'keep' is only
357 available on Linux. If using ZFS on Solaris this must be set to 'none'
358 because ZFS doesn't support it. Default: 'posix'.
361 .BI fadvise_hint \fR=\fPbool
362 Use \fBposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
363 are likely to be issued. Default: true.
366 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
367 been transferred, unless limited by other options (\fBruntime\fR, for instance).
368 Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
369 divided between the available files for the job. If not set, fio will use the
370 full size of the given files or devices. If the files do not exist, size
371 must be given. It is also possible to give size as a percentage between 1 and
372 100. If size=20% is given, fio will use 20% of the full size of the given
375 .BI io_limit \fR=\fPint
376 Normally fio operates within the region set by \fBsize\fR, which means that
377 the \fBsize\fR option sets both the region and size of IO to be performed.
378 Sometimes that is not what you want. With this option, it is possible to
379 define just the amount of IO that fio should do. For instance, if \fBsize\fR
380 is set to 20G and \fBio_limit\fR is set to 5G, fio will perform IO within
381 the first 20G but exit when 5G have been done.
383 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
384 Sets size to something really large and waits for ENOSPC (no space left on
385 device) as the terminating condition. Only makes sense with sequential write.
386 For a read workload, the mount point will be filled first then IO started on
387 the result. This option doesn't make sense if operating on a raw device node,
388 since the size of that is already known by the file system. Additionally,
389 writing beyond end-of-device will not return ENOSPC there.
391 .BI filesize \fR=\fPirange
392 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
393 for files at random within the given range, limited to \fBsize\fR in total (if
394 that is given). If \fBfilesize\fR is not specified, each created file is the
397 .BI file_append \fR=\fPbool
398 Perform IO after the end of the file. Normally fio will operate within the
399 size of a file. If this option is set, then fio will append to the file
400 instead. This has identical behavior to setting \fRoffset\fP to the size
401 of a file. This option is ignored on non-regular files.
403 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
404 Block size for I/O units. Default: 4k. Values for reads, writes, and trims
405 can be specified separately in the format \fIread\fR,\fIwrite\fR,\fItrim\fR
406 either of which may be empty to leave that value at its default. If a trailing
407 comma isn't given, the remainder will inherit the last value set.
409 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
410 Specify a range of I/O block sizes. The issued I/O unit will always be a
411 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
412 to both reads and writes if only one range is given, but can be specified
413 separately with a comma separating the values. Example: bsrange=1k-4k,2k-8k.
414 Also (see \fBblocksize\fR).
416 .BI bssplit \fR=\fPstr
417 This option allows even finer grained control of the block sizes issued,
418 not just even splits between them. With this option, you can weight various
419 block sizes for exact control of the issued IO for a job that has mixed
420 block sizes. The format of the option is bssplit=blocksize/percentage,
421 optionally adding as many definitions as needed separated by a colon.
422 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
423 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
424 splits to reads and writes. The format is identical to what the
425 \fBbs\fR option accepts, the read and write parts are separated with a
428 .B blocksize_unaligned\fR,\fP bs_unaligned
429 If set, any size in \fBblocksize_range\fR may be used. This typically won't
430 work with direct I/O, as that normally requires sector alignment.
432 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
433 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
434 the minimum blocksize given. Minimum alignment is typically 512b
435 for using direct IO, though it usually depends on the hardware block size.
436 This option is mutually exclusive with using a random map for files, so it
437 will turn off that option.
439 .BI bs_is_seq_rand \fR=\fPbool
440 If this option is set, fio will use the normal read,write blocksize settings as
441 sequential,random instead. Any random read or write will use the WRITE
442 blocksize settings, and any sequential read or write will use the READ
446 Initialize buffers with all zeros. Default: fill buffers with random data.
447 The resulting IO buffers will not be completely zeroed, unless
448 \fPscramble_buffers\fR is also turned off.
451 If this option is given, fio will refill the IO buffers on every submit. The
452 default is to only fill it at init time and reuse that data. Only makes sense
453 if zero_buffers isn't specified, naturally. If data verification is enabled,
454 refill_buffers is also automatically enabled.
456 .BI scramble_buffers \fR=\fPbool
457 If \fBrefill_buffers\fR is too costly and the target is using data
458 deduplication, then setting this option will slightly modify the IO buffer
459 contents to defeat normal de-dupe attempts. This is not enough to defeat
460 more clever block compression attempts, but it will stop naive dedupe
461 of blocks. Default: true.
463 .BI buffer_compress_percentage \fR=\fPint
464 If this is set, then fio will attempt to provide IO buffer content (on WRITEs)
465 that compress to the specified level. Fio does this by providing a mix of
466 random data and zeroes. Note that this is per block size unit, for file/disk
467 wide compression level that matches this setting, you'll also want to set
468 \fBrefill_buffers\fR.
470 .BI buffer_compress_chunk \fR=\fPint
471 See \fBbuffer_compress_percentage\fR. This setting allows fio to manage how
472 big the ranges of random data and zeroed data is. Without this set, fio will
473 provide \fBbuffer_compress_percentage\fR of blocksize random data, followed by
474 the remaining zeroed. With this set to some chunk size smaller than the block
475 size, fio can alternate random and zeroed data throughout the IO buffer.
477 .BI buffer_pattern \fR=\fPstr
478 If set, fio will fill the IO buffers with this pattern. If not set, the contents
479 of IO buffers is defined by the other options related to buffer contents. The
480 setting can be any pattern of bytes, and can be prefixed with 0x for hex
481 values. It may also be a string, where the string must then be wrapped with
484 .BI dedupe_percentage \fR=\fPint
485 If set, fio will generate this percentage of identical buffers when writing.
486 These buffers will be naturally dedupable. The contents of the buffers depend
487 on what other buffer compression settings have been set. It's possible to have
488 the individual buffers either fully compressible, or not at all. This option
489 only controls the distribution of unique buffers.
491 .BI nrfiles \fR=\fPint
492 Number of files to use for this job. Default: 1.
494 .BI openfiles \fR=\fPint
495 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
497 .BI file_service_type \fR=\fPstr
498 Defines how files to service are selected. The following types are defined:
503 Choose a file at random.
506 Round robin over opened files (default).
509 Do each file in the set sequentially.
512 The number of I/Os to issue before switching to a new file can be specified by
513 appending `:\fIint\fR' to the service type.
516 .BI ioengine \fR=\fPstr
517 Defines how the job issues I/O. The following types are defined:
522 Basic \fBread\fR\|(2) or \fBwrite\fR\|(2) I/O. \fBfseek\fR\|(2) is used to
523 position the I/O location.
526 Basic \fBpread\fR\|(2) or \fBpwrite\fR\|(2) I/O.
529 Basic \fBreadv\fR\|(2) or \fBwritev\fR\|(2) I/O. Will emulate queuing by
530 coalescing adjacent IOs into a single submission.
533 Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
536 Linux native asynchronous I/O. This ioengine defines engine specific options.
539 POSIX asynchronous I/O using \fBaio_read\fR\|(3) and \fBaio_write\fR\|(3).
542 Solaris native asynchronous I/O.
545 Windows native asynchronous I/O.
548 File is memory mapped with \fBmmap\fR\|(2) and data copied using
552 \fBsplice\fR\|(2) is used to transfer the data and \fBvmsplice\fR\|(2) to
553 transfer data from user-space to the kernel.
556 Use the syslet system calls to make regular read/write asynchronous.
559 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
560 the target is an sg character device, we use \fBread\fR\|(2) and
561 \fBwrite\fR\|(2) for asynchronous I/O.
564 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
565 itself and for debugging and testing purposes.
568 Transfer over the network. The protocol to be used can be defined with the
569 \fBprotocol\fR parameter. Depending on the protocol, \fBfilename\fR,
570 \fBhostname\fR, \fBport\fR, or \fBlisten\fR must be specified.
571 This ioengine defines engine specific options.
574 Like \fBnet\fR, but uses \fBsplice\fR\|(2) and \fBvmsplice\fR\|(2) to map data
575 and send/receive. This ioengine defines engine specific options.
578 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
579 \fBcpucycles\fR parameters.
582 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
583 approach to asynchronous I/O.
585 See <http://www.xmailserver.org/guasi\-lib.html>.
588 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
589 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
592 Loads an external I/O engine object file. Append the engine filename as
596 IO engine that does regular linux native fallocate call to simulate data
597 transfer as fio ioengine
599 DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
601 DIR_WRITE does fallocate(,mode = 0)
603 DDIR_TRIM does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)
606 IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
607 request to DDIR_WRITE event
610 IO engine supporting direct access to Ceph Rados Block Devices (RBD) via librbd
611 without the need to use the kernel rbd driver. This ioengine defines engine specific
615 Using Glusterfs libgfapi sync interface to direct access to Glusterfs volumes without
616 having to go through FUSE. This ioengine defines engine specific
620 Using Glusterfs libgfapi async interface to direct access to Glusterfs volumes without
621 having to go through FUSE. This ioengine defines engine specific
625 Read and write through Hadoop (HDFS). The \fBfilename\fR option is used to
626 specify host,port of the hdfs name-node to connect. This engine interprets
627 offsets a little differently. In HDFS, files once created cannot be modified.
628 So random writes are not possible. To imitate this, libhdfs engine expects
629 bunch of small files to be created over HDFS, and engine will randomly pick a
630 file out of those files based on the offset generated by fio backend. (see the
631 example job file to create such files, use rw=write option). Please note, you
632 might want to set necessary environment variables to work with hdfs/libhdfs
638 .BI iodepth \fR=\fPint
639 Number of I/O units to keep in flight against the file. Note that increasing
640 iodepth beyond 1 will not affect synchronous ioengines (except for small
641 degress when verify_async is in use). Even async engines may impose OS
642 restrictions causing the desired depth not to be achieved. This may happen on
643 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
644 not async on that OS. Keep an eye on the IO depth distribution in the
645 fio output to verify that the achieved depth is as expected. Default: 1.
647 .BI iodepth_batch \fR=\fPint
648 Number of I/Os to submit at once. Default: \fBiodepth\fR.
650 .BI iodepth_batch_complete \fR=\fPint
651 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
652 means that we'll ask for a minimum of 1 IO in the retrieval process from the
653 kernel. The IO retrieval will go on until we hit the limit set by
654 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
655 completed events before queuing more IO. This helps reduce IO latency, at the
656 cost of more retrieval system calls.
658 .BI iodepth_low \fR=\fPint
659 Low watermark indicating when to start filling the queue again. Default:
662 .BI direct \fR=\fPbool
663 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
665 .BI atomic \fR=\fPbool
666 If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
667 to be stable once acknowledged by the operating system. Only Linux supports
670 .BI buffered \fR=\fPbool
671 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
674 .BI offset \fR=\fPint
675 Offset in the file to start I/O. Data before the offset will not be touched.
677 .BI offset_increment \fR=\fPint
678 If this is provided, then the real offset becomes the
679 offset + offset_increment * thread_number, where the thread number is a
680 counter that starts at 0 and is incremented for each sub-job (i.e. when
681 numjobs option is specified). This option is useful if there are several jobs
682 which are intended to operate on a file in parallel disjoint segments, with
683 even spacing between the starting points.
685 .BI number_ios \fR=\fPint
686 Fio will normally perform IOs until it has exhausted the size of the region
687 set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
688 condition). With this setting, the range/size can be set independently of
689 the number of IOs to perform. When fio reaches this number, it will exit
690 normally and report status. Note that this does not extend the amount
691 of IO that will be done, it will only stop fio if this condition is met
692 before other end-of-job criteria.
695 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
696 0, don't sync. Default: 0.
698 .BI fdatasync \fR=\fPint
699 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
700 data parts of the file. Default: 0.
702 .BI write_barrier \fR=\fPint
703 Make every Nth write a barrier write.
705 .BI sync_file_range \fR=\fPstr:int
706 Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
707 track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
708 \fRstr\fP can currently be one or more of:
712 SYNC_FILE_RANGE_WAIT_BEFORE
715 SYNC_FILE_RANGE_WRITE
718 SYNC_FILE_RANGE_WRITE
722 So if you do sync_file_range=wait_before,write:8, fio would use
723 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
724 Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
726 .BI overwrite \fR=\fPbool
727 If writing, setup the file first and do overwrites. Default: false.
729 .BI end_fsync \fR=\fPbool
730 Sync file contents when a write stage has completed. Default: false.
732 .BI fsync_on_close \fR=\fPbool
733 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
734 it will happen on every close, not just at the end of the job. Default: false.
736 .BI rwmixread \fR=\fPint
737 Percentage of a mixed workload that should be reads. Default: 50.
739 .BI rwmixwrite \fR=\fPint
740 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
741 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
742 overrides the first. This may interfere with a given rate setting, if fio is
743 asked to limit reads or writes to a certain rate. If that is the case, then
744 the distribution may be skewed. Default: 50.
746 .BI random_distribution \fR=\fPstr:float
747 By default, fio will use a completely uniform random distribution when asked
748 to perform random IO. Sometimes it is useful to skew the distribution in
749 specific ways, ensuring that some parts of the data is more hot than others.
750 Fio includes the following distribution models:
754 Uniform random distribution
764 When using a zipf or pareto distribution, an input value is also needed to
765 define the access pattern. For zipf, this is the zipf theta. For pareto,
766 it's the pareto power. Fio includes a test program, genzipf, that can be
767 used visualize what the given input values will yield in terms of hit rates.
768 If you wanted to use zipf with a theta of 1.2, you would use
769 random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
770 fio will disable use of the random map.
772 .BI percentage_random \fR=\fPint
773 For a random workload, set how big a percentage should be random. This defaults
774 to 100%, in which case the workload is fully random. It can be set from
775 anywhere from 0 to 100. Setting it to 0 would make the workload fully
776 sequential. It is possible to set different values for reads, writes, and
777 trim. To do so, simply use a comma separated list. See \fBblocksize\fR.
780 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
781 this parameter is given, a new offset will be chosen without looking at past
782 I/O history. This parameter is mutually exclusive with \fBverify\fR.
784 .BI softrandommap \fR=\fPbool
785 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
786 fails to allocate the map, if this option is set it will continue without a
787 random block map. As coverage will not be as complete as with random maps, this
788 option is disabled by default.
790 .BI random_generator \fR=\fPstr
791 Fio supports the following engines for generating IO offsets for random IO:
795 Strong 2^88 cycle random number generator
798 Linear feedback shift register generator
802 Tausworthe is a strong random number generator, but it requires tracking on the
803 side if we want to ensure that blocks are only read or written once. LFSR
804 guarantees that we never generate the same offset twice, and it's also less
805 computationally expensive. It's not a true random generator, however, though
806 for IO purposes it's typically good enough. LFSR only works with single block
807 sizes, not with workloads that use multiple block sizes. If used with such a
808 workload, fio may read or write some blocks multiple times.
811 Run job with given nice value. See \fBnice\fR\|(2).
814 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
817 .BI prioclass \fR=\fPint
818 Set I/O priority class. See \fBionice\fR\|(1).
820 .BI thinktime \fR=\fPint
821 Stall job for given number of microseconds between issuing I/Os.
823 .BI thinktime_spin \fR=\fPint
824 Pretend to spend CPU time for given number of microseconds, sleeping the rest
825 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
827 .BI thinktime_blocks \fR=\fPint
828 Only valid if thinktime is set - control how many blocks to issue, before
829 waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
830 make fio wait \fBthinktime\fR microseconds after every block. This
831 effectively makes any queue depth setting redundant, since no more than 1 IO
832 will be queued before we have to complete it and do our thinktime. In other
833 words, this setting effectively caps the queue depth if the latter is larger.
837 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
838 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
839 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
840 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
841 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
842 limit writes (to 500KB/sec), the latter will only limit reads.
844 .BI ratemin \fR=\fPint
845 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
846 Failing to meet this requirement will cause the job to exit. The same format
847 as \fBrate\fR is used for read vs write separation.
849 .BI rate_iops \fR=\fPint
850 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
851 specified independently of bandwidth. The same format as \fBrate\fR is used for
852 read vs write separation. If \fBblocksize\fR is a range, the smallest block
853 size is used as the metric.
855 .BI rate_iops_min \fR=\fPint
856 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
857 is used for read vs write separation.
859 .BI ratecycle \fR=\fPint
860 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
861 milliseconds. Default: 1000ms.
863 .BI latency_target \fR=\fPint
864 If set, fio will attempt to find the max performance point that the given
865 workload will run at while maintaining a latency below this target. The
866 values is given in microseconds. See \fBlatency_window\fR and
867 \fBlatency_percentile\fR.
869 .BI latency_window \fR=\fPint
870 Used with \fBlatency_target\fR to specify the sample window that the job
871 is run at varying queue depths to test the performance. The value is given
874 .BI latency_percentile \fR=\fPfloat
875 The percentage of IOs that must fall within the criteria specified by
876 \fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
877 to 100.0, meaning that all IOs must be equal or below to the value set
878 by \fBlatency_target\fR.
880 .BI max_latency \fR=\fPint
881 If set, fio will exit the job if it exceeds this maximum latency. It will exit
884 .BI cpumask \fR=\fPint
885 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
886 may run on. See \fBsched_setaffinity\fR\|(2).
888 .BI cpus_allowed \fR=\fPstr
889 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
891 .BI cpus_allowed_policy \fR=\fPstr
892 Set the policy of how fio distributes the CPUs specified by \fBcpus_allowed\fR
893 or \fBcpumask\fR. Two policies are supported:
898 All jobs will share the CPU set specified.
901 Each job will get a unique CPU from the CPU set.
904 \fBshared\fR is the default behaviour, if the option isn't specified. If
905 \fBsplit\fR is specified, then fio will assign one cpu per job. If not enough
906 CPUs are given for the jobs listed, then fio will roundrobin the CPUs in
911 .BI numa_cpu_nodes \fR=\fPstr
912 Set this job running on specified NUMA nodes' CPUs. The arguments allow
913 comma delimited list of cpu numbers, A-B ranges, or 'all'.
915 .BI numa_mem_policy \fR=\fPstr
916 Set this job's memory policy and corresponding NUMA nodes. Format of
920 .B <mode>[:<nodelist>]
923 is one of the following memory policy:
925 .B default, prefer, bind, interleave, local
928 For \fBdefault\fR and \fBlocal\fR memory policy, no \fBnodelist\fR is
929 needed to be specified. For \fBprefer\fR, only one node is
930 allowed. For \fBbind\fR and \fBinterleave\fR, \fBnodelist\fR allows
931 comma delimited list of numbers, A-B ranges, or 'all'.
933 .BI startdelay \fR=\fPirange
934 Delay start of job for the specified number of seconds. Supports all time
935 suffixes to allow specification of hours, minutes, seconds and
936 milliseconds - seconds are the default if a unit is ommited.
937 Can be given as a range which causes each thread to choose randomly out of the
940 .BI runtime \fR=\fPint
941 Terminate processing after the specified number of seconds.
944 If given, run for the specified \fBruntime\fR duration even if the files are
945 completely read or written. The same workload will be repeated as many times
946 as \fBruntime\fR allows.
948 .BI ramp_time \fR=\fPint
949 If set, fio will run the specified workload for this amount of time before
950 logging any performance numbers. Useful for letting performance settle before
951 logging results, thus minimizing the runtime required for stable results. Note
952 that the \fBramp_time\fR is considered lead in time for a job, thus it will
953 increase the total runtime if a special timeout or runtime is specified.
955 .BI invalidate \fR=\fPbool
956 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
959 Use synchronous I/O for buffered writes. For the majority of I/O engines,
960 this means using O_SYNC. Default: false.
962 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
963 Allocation method for I/O unit buffer. Allowed values are:
968 Allocate memory with \fBmalloc\fR\|(3).
971 Use shared memory buffers allocated through \fBshmget\fR\|(2).
974 Same as \fBshm\fR, but use huge pages as backing.
977 Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
978 is given after the option in the format `:\fIfile\fR'.
981 Same as \fBmmap\fR, but use huge files as backing.
984 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
985 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
986 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
987 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
988 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
989 and the documentation for that. Normally you just need to echo an appropriate
990 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
994 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
995 This indicates the memory alignment of the IO memory buffers. Note that the
996 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
997 the alignment of the following buffers are given by the \fBbs\fR used. In
998 other words, if using a \fBbs\fR that is a multiple of the page sized in the
999 system, all buffers will be aligned to this value. If using a \fBbs\fR that
1000 is not page aligned, the alignment of subsequent IO memory buffers is the
1001 sum of the \fBiomem_align\fR and \fBbs\fR used.
1003 .BI hugepage\-size \fR=\fPint
1004 Defines the size of a huge page. Must be at least equal to the system setting.
1005 Should be a multiple of 1MB. Default: 4MB.
1008 Terminate all jobs when one finishes. Default: wait for each job to finish.
1010 .BI bwavgtime \fR=\fPint
1011 Average bandwidth calculations over the given time in milliseconds. Default:
1014 .BI iopsavgtime \fR=\fPint
1015 Average IOPS calculations over the given time in milliseconds. Default:
1018 .BI create_serialize \fR=\fPbool
1019 If true, serialize file creation for the jobs. Default: true.
1021 .BI create_fsync \fR=\fPbool
1022 \fBfsync\fR\|(2) data file after creation. Default: true.
1024 .BI create_on_open \fR=\fPbool
1025 If true, the files are not created until they are opened for IO by the job.
1027 .BI create_only \fR=\fPbool
1028 If true, fio will only run the setup phase of the job. If files need to be
1029 laid out or updated on disk, only that will be done. The actual job contents
1032 .BI pre_read \fR=\fPbool
1033 If this is given, files will be pre-read into memory before starting the given
1034 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
1035 pointless to pre-read and then drop the cache. This will only work for IO
1036 engines that are seekable, since they allow you to read the same data
1037 multiple times. Thus it will not work on eg network or splice IO.
1039 .BI unlink \fR=\fPbool
1040 Unlink job files when done. Default: false.
1042 .BI loops \fR=\fPint
1043 Specifies the number of iterations (runs of the same workload) of this job.
1046 .BI verify_only \fR=\fPbool
1047 Do not perform the specified workload, only verify data still matches previous
1048 invocation of this workload. This option allows one to check data multiple
1049 times at a later date without overwriting it. This option makes sense only for
1050 workloads that write data, and does not support workloads with the
1051 \fBtime_based\fR option set.
1053 .BI do_verify \fR=\fPbool
1054 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
1057 .BI verify \fR=\fPstr
1058 Method of verifying file contents after each iteration of the job. Allowed
1063 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1 xxhash
1064 Store appropriate checksum in the header of each block. crc32c-intel is
1065 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
1066 not supported by the system.
1069 Write extra information about each I/O (timestamp, block number, etc.). The
1070 block number is verified. See \fBverify_pattern\fR as well.
1073 Pretend to verify. Used for testing internals.
1076 This option can be used for repeated burn-in tests of a system to make sure
1077 that the written data is also correctly read back. If the data direction given
1078 is a read or random read, fio will assume that it should verify a previously
1079 written file. If the data direction includes any form of write, the verify will
1080 be of the newly written data.
1083 .BI verifysort \fR=\fPbool
1084 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
1085 read them back in a sorted manner. Default: true.
1087 .BI verifysort_nr \fR=\fPint
1088 Pre-load and sort verify blocks for a read workload.
1090 .BI verify_offset \fR=\fPint
1091 Swap the verification header with data somewhere else in the block before
1092 writing. It is swapped back before verifying.
1094 .BI verify_interval \fR=\fPint
1095 Write the verification header for this number of bytes, which should divide
1096 \fBblocksize\fR. Default: \fBblocksize\fR.
1098 .BI verify_pattern \fR=\fPstr
1099 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
1100 with totally random bytes, but sometimes it's interesting to fill with a known
1101 pattern for io verification purposes. Depending on the width of the pattern,
1102 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
1103 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
1104 has to be a hex number that starts with either "0x" or "0X". Use with
1107 .BI verify_fatal \fR=\fPbool
1108 If true, exit the job on the first observed verification failure. Default:
1111 .BI verify_dump \fR=\fPbool
1112 If set, dump the contents of both the original data block and the data block we
1113 read off disk to files. This allows later analysis to inspect just what kind of
1114 data corruption occurred. Off by default.
1116 .BI verify_async \fR=\fPint
1117 Fio will normally verify IO inline from the submitting thread. This option
1118 takes an integer describing how many async offload threads to create for IO
1119 verification instead, causing fio to offload the duty of verifying IO contents
1120 to one or more separate threads. If using this offload option, even sync IO
1121 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
1122 allows them to have IO in flight while verifies are running.
1124 .BI verify_async_cpus \fR=\fPstr
1125 Tell fio to set the given CPU affinity on the async IO verification threads.
1126 See \fBcpus_allowed\fP for the format used.
1128 .BI verify_backlog \fR=\fPint
1129 Fio will normally verify the written contents of a job that utilizes verify
1130 once that job has completed. In other words, everything is written then
1131 everything is read back and verified. You may want to verify continually
1132 instead for a variety of reasons. Fio stores the meta data associated with an
1133 IO block in memory, so for large verify workloads, quite a bit of memory would
1134 be used up holding this meta data. If this option is enabled, fio will write
1135 only N blocks before verifying these blocks.
1137 .BI verify_backlog_batch \fR=\fPint
1138 Control how many blocks fio will verify if verify_backlog is set. If not set,
1139 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
1140 read back and verified). If \fBverify_backlog_batch\fR is less than
1141 \fBverify_backlog\fR then not all blocks will be verified, if
1142 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
1143 will be verified more than once.
1145 .BI trim_percentage \fR=\fPint
1146 Number of verify blocks to discard/trim.
1148 .BI trim_verify_zero \fR=\fPbool
1149 Verify that trim/discarded blocks are returned as zeroes.
1151 .BI trim_backlog \fR=\fPint
1152 Trim after this number of blocks are written.
1154 .BI trim_backlog_batch \fR=\fPint
1155 Trim this number of IO blocks.
1157 .BI experimental_verify \fR=\fPbool
1158 Enable experimental verification.
1160 .B stonewall "\fR,\fP wait_for_previous"
1161 Wait for preceding jobs in the job file to exit before starting this one.
1162 \fBstonewall\fR implies \fBnew_group\fR.
1165 Start a new reporting group. If not given, all jobs in a file will be part
1166 of the same reporting group, unless separated by a stonewall.
1168 .BI numjobs \fR=\fPint
1169 Number of clones (processes/threads performing the same workload) of this job.
1173 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
1177 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
1178 with \fBfork\fR\|(2).
1180 .BI zonesize \fR=\fPint
1181 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
1183 .BI zonerange \fR=\fPint
1184 Give size of an IO zone. See \fBzoneskip\fR.
1186 .BI zoneskip \fR=\fPint
1187 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
1190 .BI write_iolog \fR=\fPstr
1191 Write the issued I/O patterns to the specified file. Specify a separate file
1192 for each job, otherwise the iologs will be interspersed and the file may be
1195 .BI read_iolog \fR=\fPstr
1196 Replay the I/O patterns contained in the specified file generated by
1197 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
1199 .BI replay_no_stall \fR=\fPint
1200 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1201 attempts to respect timing information between I/Os. Enabling
1202 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
1203 still respecting ordering.
1205 .BI replay_redirect \fR=\fPstr
1206 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1207 is to replay the IOPS onto the major/minor device that each IOP was recorded
1208 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
1209 single specified device regardless of the device it was recorded from.
1211 .BI write_bw_log \fR=\fPstr
1212 If given, write a bandwidth log of the jobs in this job file. Can be used to
1213 store data of the bandwidth of the jobs in their lifetime. The included
1214 fio_generate_plots script uses gnuplot to turn these text files into nice
1215 graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
1216 option, the postfix is _bw.x.log, where x is the index of the job (1..N,
1217 where N is the number of jobs)
1219 .BI write_lat_log \fR=\fPstr
1220 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
1221 filename is given with this option, the default filename of
1222 "jobname_type.x.log" is used, where x is the index of the job (1..N, where
1223 N is the number of jobs). Even if the filename is given, fio will still
1224 append the type of log.
1226 .BI write_iops_log \fR=\fPstr
1227 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
1228 option, the default filename of "jobname_type.x.log" is used, where x is the
1229 index of the job (1..N, where N is the number of jobs). Even if the filename
1230 is given, fio will still append the type of log.
1232 .BI log_avg_msec \fR=\fPint
1233 By default, fio will log an entry in the iops, latency, or bw log for every
1234 IO that completes. When writing to the disk log, that can quickly grow to a
1235 very large size. Setting this option makes fio average the each log entry
1236 over the specified period of time, reducing the resolution of the log.
1239 .BI log_offset \fR=\fPbool
1240 If this is set, the iolog options will include the byte offset for the IO
1241 entry as well as the other data values.
1243 .BI log_compression \fR=\fPint
1244 If this is set, fio will compress the IO logs as it goes, to keep the memory
1245 footprint lower. When a log reaches the specified size, that chunk is removed
1246 and compressed in the background. Given that IO logs are fairly highly
1247 compressible, this yields a nice memory savings for longer runs. The downside
1248 is that the compression will consume some background CPU cycles, so it may
1249 impact the run. This, however, is also true if the logging ends up consuming
1250 most of the system memory. So pick your poison. The IO logs are saved
1251 normally at the end of a run, by decompressing the chunks and storing them
1252 in the specified log file. This feature depends on the availability of zlib.
1254 .BI log_store_compressed \fR=\fPbool
1255 If set, and \fBlog\fR_compression is also set, fio will store the log files in
1256 a compressed format. They can be decompressed with fio, using the
1257 \fB\-\-inflate-log\fR command line parameter. The files will be stored with a
1260 .BI disable_lat \fR=\fPbool
1261 Disable measurements of total latency numbers. Useful only for cutting
1262 back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
1263 really high IOPS rates. Note that to really get rid of a large amount of these
1264 calls, this option must be used with disable_slat and disable_bw as well.
1266 .BI disable_clat \fR=\fPbool
1267 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
1269 .BI disable_slat \fR=\fPbool
1270 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
1272 .BI disable_bw_measurement \fR=\fPbool
1273 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
1275 .BI lockmem \fR=\fPint
1276 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
1277 simulate a smaller amount of memory. The amount specified is per worker.
1279 .BI exec_prerun \fR=\fPstr
1280 Before running the job, execute the specified command with \fBsystem\fR\|(3).
1282 Output is redirected in a file called \fBjobname.prerun.txt\fR
1285 .BI exec_postrun \fR=\fPstr
1286 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
1288 Output is redirected in a file called \fBjobname.postrun.txt\fR
1291 .BI ioscheduler \fR=\fPstr
1292 Attempt to switch the device hosting the file to the specified I/O scheduler.
1294 .BI disk_util \fR=\fPbool
1295 Generate disk utilization statistics if the platform supports it. Default: true.
1297 .BI clocksource \fR=\fPstr
1298 Use the given clocksource as the base of timing. The supported options are:
1302 \fBgettimeofday\fR\|(2)
1305 \fBclock_gettime\fR\|(2)
1308 Internal CPU clock source
1312 \fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
1313 (and fio is heavy on time calls). Fio will automatically use this clocksource
1314 if it's supported and considered reliable on the system it is running on,
1315 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
1316 means supporting TSC Invariant.
1318 .BI gtod_reduce \fR=\fPbool
1319 Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
1320 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
1321 \fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
1322 the gtod() calls we would have done if all time keeping was enabled.
1324 .BI gtod_cpu \fR=\fPint
1325 Sometimes it's cheaper to dedicate a single thread of execution to just getting
1326 the current time. Fio (and databases, for instance) are very intensive on
1327 \fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
1328 nothing but logging current time to a shared memory location. Then the other
1329 threads/processes that run IO workloads need only copy that segment, instead of
1330 entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
1331 these time calls will be excluded from other uses. Fio will manually clear it
1332 from the CPU mask of other jobs.
1334 .BI ignore_error \fR=\fPstr
1335 Sometimes you want to ignore some errors during test in that case you can specify
1336 error list for each error type.
1338 ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
1340 errors for given error type is separated with ':'.
1341 Error may be symbol ('ENOSPC', 'ENOMEM') or an integer.
1343 Example: ignore_error=EAGAIN,ENOSPC:122 .
1345 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from WRITE.
1347 .BI error_dump \fR=\fPbool
1348 If set dump every error even if it is non fatal, true by default. If disabled
1349 only fatal error will be dumped
1351 .BI profile \fR=\fPstr
1352 Select a specific builtin performance test.
1354 .BI cgroup \fR=\fPstr
1355 Add job to this control group. If it doesn't exist, it will be created.
1356 The system must have a mounted cgroup blkio mount point for this to work. If
1357 your system doesn't have it mounted, you can do so with:
1359 # mount \-t cgroup \-o blkio none /cgroup
1361 .BI cgroup_weight \fR=\fPint
1362 Set the weight of the cgroup to this value. See the documentation that comes
1363 with the kernel, allowed values are in the range of 100..1000.
1365 .BI cgroup_nodelete \fR=\fPbool
1366 Normally fio will delete the cgroups it has created after the job completion.
1367 To override this behavior and to leave cgroups around after the job completion,
1368 set cgroup_nodelete=1. This can be useful if one wants to inspect various
1369 cgroup files after job completion. Default: false
1372 Instead of running as the invoking user, set the user ID to this value before
1373 the thread/process does any work.
1376 Set group ID, see \fBuid\fR.
1378 .BI unit_base \fR=\fPint
1379 Base unit for reporting. Allowed values are:
1383 Use auto-detection (default).
1393 .BI flow_id \fR=\fPint
1394 The ID of the flow. If not specified, it defaults to being a global flow. See
1398 Weight in token-based flow control. If this value is used, then there is a
1399 \fBflow counter\fR which is used to regulate the proportion of activity between
1400 two or more jobs. fio attempts to keep this flow counter near zero. The
1401 \fBflow\fR parameter stands for how much should be added or subtracted to the
1402 flow counter on each iteration of the main I/O loop. That is, if one job has
1403 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
1404 1:8 ratio in how much one runs vs the other.
1406 .BI flow_watermark \fR=\fPint
1407 The maximum value that the absolute value of the flow counter is allowed to
1408 reach before the job must wait for a lower value of the counter.
1410 .BI flow_sleep \fR=\fPint
1411 The period of time, in microseconds, to wait after the flow watermark has been
1412 exceeded before retrying operations
1414 .BI clat_percentiles \fR=\fPbool
1415 Enable the reporting of percentiles of completion latencies.
1417 .BI percentile_list \fR=\fPfloat_list
1418 Overwrite the default list of percentiles for completion
1419 latencies. Each number is a floating number in the range (0,100], and
1420 the maximum length of the list is 20. Use ':' to separate the
1421 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1422 report the values of completion latency below which 99.5% and 99.9% of
1423 the observed latencies fell, respectively.
1424 .SS "Ioengine Parameters List"
1425 Some parameters are only valid when a specific ioengine is in use. These are
1426 used identically to normal parameters, with the caveat that when used on the
1427 command line, they must come after the ioengine.
1429 .BI (cpu)cpuload \fR=\fPint
1430 Attempt to use the specified percentage of CPU cycles.
1432 .BI (cpu)cpuchunks \fR=\fPint
1433 Split the load into cycles of the given time. In microseconds.
1435 .BI (cpu)exit_on_io_done \fR=\fPbool
1436 Detect when IO threads are done, then exit.
1438 .BI (libaio)userspace_reap
1439 Normally, with the libaio engine in use, fio will use
1440 the io_getevents system call to reap newly returned events.
1441 With this flag turned on, the AIO ring will be read directly
1442 from user-space to reap events. The reaping mode is only
1443 enabled when polling for a minimum of 0 events (eg when
1444 iodepth_batch_complete=0).
1446 .BI (net,netsplice)hostname \fR=\fPstr
1447 The host name or IP address to use for TCP or UDP based IO.
1448 If the job is a TCP listener or UDP reader, the hostname is not
1449 used and must be omitted unless it is a valid UDP multicast address.
1451 .BI (net,netsplice)port \fR=\fPint
1452 The TCP or UDP port to bind to or connect to.
1454 .BI (net,netsplice)interface \fR=\fPstr
1455 The IP address of the network interface used to send or receive UDP multicast
1458 .BI (net,netsplice)ttl \fR=\fPint
1459 Time-to-live value for outgoing UDP multicast packets. Default: 1
1461 .BI (net,netsplice)nodelay \fR=\fPbool
1462 Set TCP_NODELAY on TCP connections.
1464 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1465 The network protocol to use. Accepted values are:
1470 Transmission control protocol
1473 Transmission control protocol V6
1476 User datagram protocol
1479 User datagram protocol V6
1485 When the protocol is TCP or UDP, the port must also be given,
1486 as well as the hostname if the job is a TCP listener or UDP
1487 reader. For unix sockets, the normal filename option should be
1488 used and the port is invalid.
1491 .BI (net,netsplice)listen
1492 For TCP network connections, tell fio to listen for incoming
1493 connections rather than initiating an outgoing connection. The
1494 hostname must be omitted if this option is used.
1496 .BI (net, pingpong) \fR=\fPbool
1497 Normally a network writer will just continue writing data, and a network reader
1498 will just consume packets. If pingpong=1 is set, a writer will send its normal
1499 payload to the reader, then wait for the reader to send the same payload back.
1500 This allows fio to measure network latencies. The submission and completion
1501 latencies then measure local time spent sending or receiving, and the
1502 completion latency measures how long it took for the other end to receive and
1503 send back. For UDP multicast traffic pingpong=1 should only be set for a single
1504 reader when multiple readers are listening to the same address.
1506 .BI (e4defrag,donorname) \fR=\fPstr
1507 File will be used as a block donor (swap extents between files)
1509 .BI (e4defrag,inplace) \fR=\fPint
1510 Configure donor file block allocation strategy
1513 Preallocate donor's file on init
1516 allocate space immediately inside defragment event, and free right after event
1519 .BI (rbd)rbdname \fR=\fPstr
1520 Specifies the name of the RBD.
1522 .BI (rbd)pool \fR=\fPstr
1523 Specifies the name of the Ceph pool containing the RBD.
1525 .BI (rbd)clientname \fR=\fPstr
1526 Specifies the username (without the 'client.' prefix) used to access the Ceph cluster.
1528 While running, \fBfio\fR will display the status of the created jobs. For
1532 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1535 The characters in the first set of brackets denote the current status of each
1536 threads. The possible values are:
1542 Setup but not started.
1548 Initialized, waiting.
1551 Running, doing sequential reads.
1554 Running, doing random reads.
1557 Running, doing sequential writes.
1560 Running, doing random writes.
1563 Running, doing mixed sequential reads/writes.
1566 Running, doing mixed random reads/writes.
1569 Running, currently waiting for \fBfsync\fR\|(2).
1572 Running, verifying written data.
1575 Exited, not reaped by main thread.
1578 Exited, thread reaped.
1582 The second set of brackets shows the estimated completion percentage of
1583 the current group. The third set shows the read and write I/O rate,
1584 respectively. Finally, the estimated run time of the job is displayed.
1586 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1587 for each thread, each group of threads, and each disk, in that order.
1589 Per-thread statistics first show the threads client number, group-id, and
1590 error code. The remaining figures are as follows:
1594 Number of megabytes of I/O performed.
1597 Average data rate (bandwidth).
1603 Submission latency minimum, maximum, average and standard deviation. This is
1604 the time it took to submit the I/O.
1607 Completion latency minimum, maximum, average and standard deviation. This
1608 is the time between submission and completion.
1611 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1612 and standard deviation.
1615 CPU usage statistics. Includes user and system time, number of context switches
1616 this thread went through and number of major and minor page faults.
1619 Distribution of I/O depths. Each depth includes everything less than (or equal)
1620 to it, but greater than the previous depth.
1623 Number of read/write requests issued, and number of short read/write requests.
1626 Distribution of I/O completion latencies. The numbers follow the same pattern
1630 The group statistics show:
1635 Number of megabytes I/O performed.
1638 Aggregate bandwidth of threads in the group.
1641 Minimum average bandwidth a thread saw.
1644 Maximum average bandwidth a thread saw.
1647 Shortest runtime of threads in the group.
1650 Longest runtime of threads in the group.
1654 Finally, disk statistics are printed with reads first:
1659 Number of I/Os performed by all groups.
1662 Number of merges in the I/O scheduler.
1665 Number of ticks we kept the disk busy.
1668 Total time spent in the disk queue.
1675 It is also possible to get fio to dump the current output while it is
1676 running, without terminating the job. To do that, send fio the \fBUSR1\fR
1679 If the \fB\-\-minimal\fR / \fB\-\-append-terse\fR options are given, the
1680 results will be printed/appended in a semicolon-delimited format suitable for
1682 A job description (if provided) follows on a new line. Note that the first
1683 number in the line is the version number. If the output has to be changed
1684 for some reason, this number will be incremented by 1 to signify that
1685 change. The fields are:
1688 .B terse version, fio version, jobname, groupid, error
1692 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1696 .B min, max, mean, standard deviation
1700 .B min, max, mean, standard deviation
1702 Completion latency percentiles (20 fields):
1704 .B Xth percentile=usec
1708 .B min, max, mean, standard deviation
1712 .B min, max, aggregate percentage of total, mean, standard deviation
1718 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1722 .B min, max, mean, standard deviation
1726 .B min, max, mean, standard deviation
1728 Completion latency percentiles (20 fields):
1730 .B Xth percentile=usec
1734 .B min, max, mean, standard deviation
1738 .B min, max, aggregate percentage of total, mean, standard deviation
1744 .B user, system, context switches, major page faults, minor page faults
1747 IO depth distribution:
1749 .B <=1, 2, 4, 8, 16, 32, >=64
1752 IO latency distribution:
1756 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1760 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1764 Disk utilization (1 for each disk used):
1766 .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
1769 Error Info (dependent on continue_on_error, default off):
1771 .B total # errors, first error code
1774 .B text description (if provided in config - appears on newline)
1777 Normally you would run fio as a stand-alone application on the machine
1778 where the IO workload should be generated. However, it is also possible to
1779 run the frontend and backend of fio separately. This makes it possible to
1780 have a fio server running on the machine(s) where the IO workload should
1781 be running, while controlling it from another machine.
1783 To start the server, you would do:
1785 \fBfio \-\-server=args\fR
1787 on that machine, where args defines what fio listens to. The arguments
1788 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1789 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain
1790 socket. 'hostname' is either a hostname or IP address, and 'port' is the port to
1791 listen to (only valid for TCP/IP, not a local socket). Some examples:
1795 Start a fio server, listening on all interfaces on the default port (8765).
1797 2) fio \-\-server=ip:hostname,4444
1799 Start a fio server, listening on IP belonging to hostname and on port 4444.
1801 3) fio \-\-server=ip6:::1,4444
1803 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1805 4) fio \-\-server=,4444
1807 Start a fio server, listening on all interfaces on port 4444.
1809 5) fio \-\-server=1.2.3.4
1811 Start a fio server, listening on IP 1.2.3.4 on the default port.
1813 6) fio \-\-server=sock:/tmp/fio.sock
1815 Start a fio server, listening on the local socket /tmp/fio.sock.
1817 When a server is running, you can connect to it from a client. The client
1820 fio \-\-local-args \-\-client=server \-\-remote-args <job file(s)>
1822 where \-\-local-args are arguments that are local to the client where it is
1823 running, 'server' is the connect string, and \-\-remote-args and <job file(s)>
1824 are sent to the server. The 'server' string follows the same format as it
1825 does on the server side, to allow IP/hostname/socket and port strings.
1826 You can connect to multiple clients as well, to do that you could run:
1828 fio \-\-client=server2 \-\-client=server2 <job file(s)>
1832 was written by Jens Axboe <jens.axboe@oracle.com>,
1833 now Jens Axboe <jaxboe@fusionio.com>.
1835 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1836 on documentation by Jens Axboe.
1837 .SH "REPORTING BUGS"
1838 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1841 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1843 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob