1 .TH fio 1 "December 2014" "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 \-\-output-format \fR=\fPformat
24 Set the reporting format to \fInormal\fR, \fIterse\fR, or \fIjson\fR.
26 .BI \-\-runtime \fR=\fPruntime
27 Limit run time to \fIruntime\fR seconds.
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.
119 Anywhere a numeric value is required, an arithmetic expression may be used,
120 provided it is surrounded by parentheses. Supported operators are:
128 .B multiplication (*)
134 .B exponentiation (^)
138 For time values in expressions, units are microseconds by default. This is
139 different than for time values not in expressions (not enclosed in
140 parentheses). The types used are:
143 String: a sequence of alphanumeric characters.
146 SI integer: a whole number, possibly containing a suffix denoting the base unit
147 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
148 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
149 respectively. If prefixed with '0x', the value is assumed to be base 16
150 (hexadecimal). A suffix may include a trailing 'b', for instance 'kb' is
151 identical to 'k'. You can specify a base 10 value by using 'KiB', 'MiB','GiB',
152 etc. This is useful for disk drives where values are often given in base 10
153 values. Specifying '30GiB' will get you 30*1000^3 bytes.
154 When specifying times the default suffix meaning changes, still denoting the
155 base unit of the value, but accepted suffixes are 'D' (days), 'H' (hours), 'M'
156 (minutes), 'S' Seconds, 'ms' (or msec) milli seconds, 'us' (or 'usec') micro
157 seconds. Time values without a unit specify seconds.
158 The suffixes are not case sensitive.
161 Boolean: a true or false value. `0' denotes false, `1' denotes true.
164 Integer range: a range of integers specified in the format
165 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
166 \fIupper\fR may contain a suffix as described above. If an option allows two
167 sets of ranges, they are separated with a `,' or `/' character. For example:
171 List of floating numbers: A list of floating numbers, separated by
176 May be used to override the job name. On the command line, this parameter
177 has the special purpose of signalling the start of a new job.
179 .BI description \fR=\fPstr
180 Human-readable description of the job. It is printed when the job is run, but
181 otherwise has no special purpose.
183 .BI directory \fR=\fPstr
184 Prefix filenames with this directory. Used to place files in a location other
186 You can specify a number of directories by separating the names with a ':'
187 character. These directories will be assigned equally distributed to job clones
188 creates with \fInumjobs\fR as long as they are using generated filenames.
189 If specific \fIfilename(s)\fR are set fio will use the first listed directory,
190 and thereby matching the \fIfilename\fR semantic which generates a file each
191 clone if not specified, but let all clones use the same if set. See
192 \fIfilename\fR for considerations regarding escaping certain characters on
195 .BI filename \fR=\fPstr
197 normally makes up a file name based on the job name, thread number, and file
198 number. If you want to share files between threads in a job or several jobs,
199 specify a \fIfilename\fR for each of them to override the default.
200 If the I/O engine is file-based, you can specify
201 a number of files by separating the names with a `:' character. `\-' is a
202 reserved name, meaning stdin or stdout, depending on the read/write direction
203 set. On Windows, disk devices are accessed as \\.\PhysicalDrive0 for the first
204 device, \\.\PhysicalDrive1 for the second etc. Note: Windows and FreeBSD
205 prevent write access to areas of the disk containing in-use data
206 (e.g. filesystems). If the wanted filename does need to include a colon, then
207 escape that with a '\\' character. For instance, if the filename is
208 "/dev/dsk/foo@3,0:c", then you would use filename="/dev/dsk/foo@3,0\\:c".
210 .BI filename_format \fR=\fPstr
211 If sharing multiple files between jobs, it is usually necessary to have
212 fio generate the exact names that you want. By default, fio will name a file
213 based on the default file format specification of
214 \fBjobname.jobnumber.filenumber\fP. With this option, that can be
215 customized. Fio will recognize and replace the following keywords in this
221 The name of the worker thread or process.
224 The incremental number of the worker thread or process.
227 The incremental number of the file for that worker thread or process.
230 To have dependent jobs share a set of files, this option can be set to
231 have fio generate filenames that are shared between the two. For instance,
232 if \fBtestfiles.$filenum\fR is specified, file number 4 for any job will
233 be named \fBtestfiles.4\fR. The default of \fB$jobname.$jobnum.$filenum\fR
234 will be used if no other format specifier is given.
238 .BI lockfile \fR=\fPstr
239 Fio defaults to not locking any files before it does IO to them. If a file or
240 file descriptor is shared, fio can serialize IO to that file to make the end
241 result consistent. This is usual for emulating real workloads that share files.
247 No locking. This is the default.
250 Only one thread or process may do IO at a time, excluding all others.
253 Read-write locking on the file. Many readers may access the file at the same
254 time, but writes get exclusive access.
258 .BI opendir \fR=\fPstr
259 Recursively open any files below directory \fIstr\fR.
261 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
262 Type of I/O pattern. Accepted values are:
273 Sequential trim (Linux block devices only).
282 Random trim (Linux block devices only).
285 Mixed sequential reads and writes.
288 Mixed random reads and writes.
291 Trim and write mixed workload. Blocks will be trimmed first, then the same
292 blocks will be written to.
295 For mixed I/O, the default split is 50/50. For certain types of io the result
296 may still be skewed a bit, since the speed may be different. It is possible to
297 specify a number of IO's to do before getting a new offset, this is done by
298 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
299 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
300 value of 8. If the postfix is used with a sequential IO pattern, then the value
301 specified will be added to the generated offset for each IO. For instance,
302 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
303 into sequential IO with holes. See the \fBrw_sequencer\fR option.
306 .BI rw_sequencer \fR=\fPstr
307 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
308 then this option controls how that number modifies the IO offset being
309 generated. Accepted values are:
314 Generate sequential offset
317 Generate the same offset
320 \fBsequential\fR is only useful for random IO, where fio would normally
321 generate a new random offset for every IO. If you append eg 8 to randread, you
322 would get a new random offset for every 8 IO's. The result would be a seek for
323 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
324 that. As sequential IO is already sequential, setting \fBsequential\fR for that
325 would not result in any differences. \fBidentical\fR behaves in a similar
326 fashion, except it sends the same offset 8 number of times before generating a
331 .BI kb_base \fR=\fPint
332 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
333 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
334 reasons. Allowed values are 1024 or 1000, with 1024 being the default.
336 .BI unified_rw_reporting \fR=\fPbool
337 Fio normally reports statistics on a per data direction basis, meaning that
338 read, write, and trim are accounted and reported separately. If this option is
339 set fio sums the results and reports them as "mixed" instead.
341 .BI randrepeat \fR=\fPbool
342 Seed the random number generator used for random I/O patterns in a predictable
343 way so the pattern is repeatable across runs. Default: true.
345 .BI allrandrepeat \fR=\fPbool
346 Seed all random number generators in a predictable way so results are
347 repeatable across runs. Default: false.
349 .BI randseed \fR=\fPint
350 Seed the random number generators based on this seed value, to be able to
351 control what sequence of output is being generated. If not set, the random
352 sequence depends on the \fBrandrepeat\fR setting.
354 .BI fallocate \fR=\fPstr
355 Whether pre-allocation is performed when laying down files. Accepted values
361 Do not pre-allocate space.
364 Pre-allocate via \fBposix_fallocate\fR\|(3).
367 Pre-allocate via \fBfallocate\fR\|(2) with FALLOC_FL_KEEP_SIZE set.
370 Backward-compatible alias for 'none'.
373 Backward-compatible alias for 'posix'.
376 May not be available on all supported platforms. 'keep' is only
377 available on Linux. If using ZFS on Solaris this must be set to 'none'
378 because ZFS doesn't support it. Default: 'posix'.
381 .BI fadvise_hint \fR=\fPbool
382 Use \fBposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
383 are likely to be issued. Default: true.
385 .BI fadvise_stream \fR=\fPint
386 Use \fBposix_fadvise\fR\|(2) to advise the kernel what stream ID the
387 writes issued belong to. Only supported on Linux. Note, this option
388 may change going forward.
391 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
392 been transferred, unless limited by other options (\fBruntime\fR, for instance,
393 or increased/descreased by \fBio_size\fR). Unless \fBnrfiles\fR and
394 \fBfilesize\fR options are given, this amount will be divided between the
395 available files for the job. If not set, fio will use the full size of the
396 given files or devices. If the files do not exist, size must be given. It is
397 also possible to give size as a percentage between 1 and 100. If size=20% is
398 given, fio will use 20% of the full size of the given files or devices.
400 .BI io_size \fR=\fPint "\fR,\fB io_limit \fR=\fPint
401 Normally fio operates within the region set by \fBsize\fR, which means that
402 the \fBsize\fR option sets both the region and size of IO to be performed.
403 Sometimes that is not what you want. With this option, it is possible to
404 define just the amount of IO that fio should do. For instance, if \fBsize\fR
405 is set to 20G and \fBio_limit\fR is set to 5G, fio will perform IO within
406 the first 20G but exit when 5G have been done. The opposite is also
407 possible - if \fBsize\fR is set to 20G, and \fBio_size\fR is set to 40G, then
408 fio will do 40G of IO within the 0..20G region.
410 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
411 Sets size to something really large and waits for ENOSPC (no space left on
412 device) as the terminating condition. Only makes sense with sequential write.
413 For a read workload, the mount point will be filled first then IO started on
414 the result. This option doesn't make sense if operating on a raw device node,
415 since the size of that is already known by the file system. Additionally,
416 writing beyond end-of-device will not return ENOSPC there.
418 .BI filesize \fR=\fPirange
419 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
420 for files at random within the given range, limited to \fBsize\fR in total (if
421 that is given). If \fBfilesize\fR is not specified, each created file is the
424 .BI file_append \fR=\fPbool
425 Perform IO after the end of the file. Normally fio will operate within the
426 size of a file. If this option is set, then fio will append to the file
427 instead. This has identical behavior to setting \fRoffset\fP to the size
428 of a file. This option is ignored on non-regular files.
430 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
431 Block size for I/O units. Default: 4k. Values for reads, writes, and trims
432 can be specified separately in the format \fIread\fR,\fIwrite\fR,\fItrim\fR
433 either of which may be empty to leave that value at its default. If a trailing
434 comma isn't given, the remainder will inherit the last value set.
436 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
437 Specify a range of I/O block sizes. The issued I/O unit will always be a
438 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
439 to both reads and writes if only one range is given, but can be specified
440 separately with a comma separating the values. Example: bsrange=1k-4k,2k-8k.
441 Also (see \fBblocksize\fR).
443 .BI bssplit \fR=\fPstr
444 This option allows even finer grained control of the block sizes issued,
445 not just even splits between them. With this option, you can weight various
446 block sizes for exact control of the issued IO for a job that has mixed
447 block sizes. The format of the option is bssplit=blocksize/percentage,
448 optionally adding as many definitions as needed separated by a colon.
449 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
450 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
451 splits to reads and writes. The format is identical to what the
452 \fBbs\fR option accepts, the read and write parts are separated with a
455 .B blocksize_unaligned\fR,\fP bs_unaligned
456 If set, any size in \fBblocksize_range\fR may be used. This typically won't
457 work with direct I/O, as that normally requires sector alignment.
459 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
460 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
461 the minimum blocksize given. Minimum alignment is typically 512b
462 for using direct IO, though it usually depends on the hardware block size.
463 This option is mutually exclusive with using a random map for files, so it
464 will turn off that option.
466 .BI bs_is_seq_rand \fR=\fPbool
467 If this option is set, fio will use the normal read,write blocksize settings as
468 sequential,random instead. Any random read or write will use the WRITE
469 blocksize settings, and any sequential read or write will use the READ
473 Initialize buffers with all zeros. Default: fill buffers with random data.
476 If this option is given, fio will refill the IO buffers on every submit. The
477 default is to only fill it at init time and reuse that data. Only makes sense
478 if zero_buffers isn't specified, naturally. If data verification is enabled,
479 refill_buffers is also automatically enabled.
481 .BI scramble_buffers \fR=\fPbool
482 If \fBrefill_buffers\fR is too costly and the target is using data
483 deduplication, then setting this option will slightly modify the IO buffer
484 contents to defeat normal de-dupe attempts. This is not enough to defeat
485 more clever block compression attempts, but it will stop naive dedupe
486 of blocks. Default: true.
488 .BI buffer_compress_percentage \fR=\fPint
489 If this is set, then fio will attempt to provide IO buffer content (on WRITEs)
490 that compress to the specified level. Fio does this by providing a mix of
491 random data and a fixed pattern. The fixed pattern is either zeroes, or the
492 pattern specified by \fBbuffer_pattern\fR. If the pattern option is used, it
493 might skew the compression ratio slightly. Note that this is per block size
494 unit, for file/disk wide compression level that matches this setting. Note
495 that this is per block size unit, for file/disk wide compression level that
496 matches this setting, you'll also want to set refill_buffers.
498 .BI buffer_compress_chunk \fR=\fPint
499 See \fBbuffer_compress_percentage\fR. This setting allows fio to manage how
500 big the ranges of random data and zeroed data is. Without this set, fio will
501 provide \fBbuffer_compress_percentage\fR of blocksize random data, followed by
502 the remaining zeroed. With this set to some chunk size smaller than the block
503 size, fio can alternate random and zeroed data throughout the IO buffer.
505 .BI buffer_pattern \fR=\fPstr
506 If set, fio will fill the IO buffers with this pattern. If not set, the contents
507 of IO buffers is defined by the other options related to buffer contents. The
508 setting can be any pattern of bytes, and can be prefixed with 0x for hex
509 values. It may also be a string, where the string must then be wrapped with
512 .BI dedupe_percentage \fR=\fPint
513 If set, fio will generate this percentage of identical buffers when writing.
514 These buffers will be naturally dedupable. The contents of the buffers depend
515 on what other buffer compression settings have been set. It's possible to have
516 the individual buffers either fully compressible, or not at all. This option
517 only controls the distribution of unique buffers.
519 .BI nrfiles \fR=\fPint
520 Number of files to use for this job. Default: 1.
522 .BI openfiles \fR=\fPint
523 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
525 .BI file_service_type \fR=\fPstr
526 Defines how files to service are selected. The following types are defined:
531 Choose a file at random.
534 Round robin over opened files (default).
537 Do each file in the set sequentially.
540 The number of I/Os to issue before switching to a new file can be specified by
541 appending `:\fIint\fR' to the service type.
544 .BI ioengine \fR=\fPstr
545 Defines how the job issues I/O. The following types are defined:
550 Basic \fBread\fR\|(2) or \fBwrite\fR\|(2) I/O. \fBfseek\fR\|(2) is used to
551 position the I/O location.
554 Basic \fBpread\fR\|(2) or \fBpwrite\fR\|(2) I/O.
557 Basic \fBreadv\fR\|(2) or \fBwritev\fR\|(2) I/O. Will emulate queuing by
558 coalescing adjacent IOs into a single submission.
561 Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
564 Linux native asynchronous I/O. This ioengine defines engine specific options.
567 POSIX asynchronous I/O using \fBaio_read\fR\|(3) and \fBaio_write\fR\|(3).
570 Solaris native asynchronous I/O.
573 Windows native asynchronous I/O.
576 File is memory mapped with \fBmmap\fR\|(2) and data copied using
580 \fBsplice\fR\|(2) is used to transfer the data and \fBvmsplice\fR\|(2) to
581 transfer data from user-space to the kernel.
584 Use the syslet system calls to make regular read/write asynchronous.
587 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
588 the target is an sg character device, we use \fBread\fR\|(2) and
589 \fBwrite\fR\|(2) for asynchronous I/O.
592 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
593 itself and for debugging and testing purposes.
596 Transfer over the network. The protocol to be used can be defined with the
597 \fBprotocol\fR parameter. Depending on the protocol, \fBfilename\fR,
598 \fBhostname\fR, \fBport\fR, or \fBlisten\fR must be specified.
599 This ioengine defines engine specific options.
602 Like \fBnet\fR, but uses \fBsplice\fR\|(2) and \fBvmsplice\fR\|(2) to map data
603 and send/receive. This ioengine defines engine specific options.
606 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
607 \fBcpucycles\fR parameters.
610 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
611 approach to asynchronous I/O.
613 See <http://www.xmailserver.org/guasi\-lib.html>.
616 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
617 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
620 Loads an external I/O engine object file. Append the engine filename as
624 IO engine that does regular linux native fallocate call to simulate data
625 transfer as fio ioengine
627 DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
629 DIR_WRITE does fallocate(,mode = 0)
631 DDIR_TRIM does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)
634 IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
635 request to DDIR_WRITE event
638 IO engine supporting direct access to Ceph Rados Block Devices (RBD) via librbd
639 without the need to use the kernel rbd driver. This ioengine defines engine specific
643 Using Glusterfs libgfapi sync interface to direct access to Glusterfs volumes without
644 having to go through FUSE. This ioengine defines engine specific
648 Using Glusterfs libgfapi async interface to direct access to Glusterfs volumes without
649 having to go through FUSE. This ioengine defines engine specific
653 Read and write through Hadoop (HDFS). The \fBfilename\fR option is used to
654 specify host,port of the hdfs name-node to connect. This engine interprets
655 offsets a little differently. In HDFS, files once created cannot be modified.
656 So random writes are not possible. To imitate this, libhdfs engine expects
657 bunch of small files to be created over HDFS, and engine will randomly pick a
658 file out of those files based on the offset generated by fio backend. (see the
659 example job file to create such files, use rw=write option). Please note, you
660 might want to set necessary environment variables to work with hdfs/libhdfs
664 Read, write and erase an MTD character device (e.g., /dev/mtd0). Discards are
665 treated as erases. Depending on the underlying device type, the I/O may have
666 to go in a certain pattern, e.g., on NAND, writing sequentially to erase blocks
667 and discarding before overwriting. The writetrim mode works well for this
673 .BI iodepth \fR=\fPint
674 Number of I/O units to keep in flight against the file. Note that increasing
675 iodepth beyond 1 will not affect synchronous ioengines (except for small
676 degress when verify_async is in use). Even async engines may impose OS
677 restrictions causing the desired depth not to be achieved. This may happen on
678 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
679 not async on that OS. Keep an eye on the IO depth distribution in the
680 fio output to verify that the achieved depth is as expected. Default: 1.
682 .BI iodepth_batch \fR=\fPint
683 Number of I/Os to submit at once. Default: \fBiodepth\fR.
685 .BI iodepth_batch_complete \fR=\fPint
686 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
687 means that we'll ask for a minimum of 1 IO in the retrieval process from the
688 kernel. The IO retrieval will go on until we hit the limit set by
689 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
690 completed events before queuing more IO. This helps reduce IO latency, at the
691 cost of more retrieval system calls.
693 .BI iodepth_low \fR=\fPint
694 Low watermark indicating when to start filling the queue again. Default:
697 .BI direct \fR=\fPbool
698 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
700 .BI atomic \fR=\fPbool
701 If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
702 to be stable once acknowledged by the operating system. Only Linux supports
705 .BI buffered \fR=\fPbool
706 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
709 .BI offset \fR=\fPint
710 Offset in the file to start I/O. Data before the offset will not be touched.
712 .BI offset_increment \fR=\fPint
713 If this is provided, then the real offset becomes the
714 offset + offset_increment * thread_number, where the thread number is a
715 counter that starts at 0 and is incremented for each sub-job (i.e. when
716 numjobs option is specified). This option is useful if there are several jobs
717 which are intended to operate on a file in parallel disjoint segments, with
718 even spacing between the starting points.
720 .BI number_ios \fR=\fPint
721 Fio will normally perform IOs until it has exhausted the size of the region
722 set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
723 condition). With this setting, the range/size can be set independently of
724 the number of IOs to perform. When fio reaches this number, it will exit
725 normally and report status. Note that this does not extend the amount
726 of IO that will be done, it will only stop fio if this condition is met
727 before other end-of-job criteria.
730 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
731 0, don't sync. Default: 0.
733 .BI fdatasync \fR=\fPint
734 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
735 data parts of the file. Default: 0.
737 .BI write_barrier \fR=\fPint
738 Make every Nth write a barrier write.
740 .BI sync_file_range \fR=\fPstr:int
741 Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
742 track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
743 \fRstr\fP can currently be one or more of:
747 SYNC_FILE_RANGE_WAIT_BEFORE
750 SYNC_FILE_RANGE_WRITE
753 SYNC_FILE_RANGE_WRITE
757 So if you do sync_file_range=wait_before,write:8, fio would use
758 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
759 Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
761 .BI overwrite \fR=\fPbool
762 If writing, setup the file first and do overwrites. Default: false.
764 .BI end_fsync \fR=\fPbool
765 Sync file contents when a write stage has completed. Default: false.
767 .BI fsync_on_close \fR=\fPbool
768 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
769 it will happen on every close, not just at the end of the job. Default: false.
771 .BI rwmixread \fR=\fPint
772 Percentage of a mixed workload that should be reads. Default: 50.
774 .BI rwmixwrite \fR=\fPint
775 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
776 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
777 overrides the first. This may interfere with a given rate setting, if fio is
778 asked to limit reads or writes to a certain rate. If that is the case, then
779 the distribution may be skewed. Default: 50.
781 .BI random_distribution \fR=\fPstr:float
782 By default, fio will use a completely uniform random distribution when asked
783 to perform random IO. Sometimes it is useful to skew the distribution in
784 specific ways, ensuring that some parts of the data is more hot than others.
785 Fio includes the following distribution models:
789 Uniform random distribution
799 When using a zipf or pareto distribution, an input value is also needed to
800 define the access pattern. For zipf, this is the zipf theta. For pareto,
801 it's the pareto power. Fio includes a test program, genzipf, that can be
802 used visualize what the given input values will yield in terms of hit rates.
803 If you wanted to use zipf with a theta of 1.2, you would use
804 random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
805 fio will disable use of the random map.
807 .BI percentage_random \fR=\fPint
808 For a random workload, set how big a percentage should be random. This defaults
809 to 100%, in which case the workload is fully random. It can be set from
810 anywhere from 0 to 100. Setting it to 0 would make the workload fully
811 sequential. It is possible to set different values for reads, writes, and
812 trim. To do so, simply use a comma separated list. See \fBblocksize\fR.
815 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
816 this parameter is given, a new offset will be chosen without looking at past
817 I/O history. This parameter is mutually exclusive with \fBverify\fR.
819 .BI softrandommap \fR=\fPbool
820 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
821 fails to allocate the map, if this option is set it will continue without a
822 random block map. As coverage will not be as complete as with random maps, this
823 option is disabled by default.
825 .BI random_generator \fR=\fPstr
826 Fio supports the following engines for generating IO offsets for random IO:
830 Strong 2^88 cycle random number generator
833 Linear feedback shift register generator
837 Tausworthe is a strong random number generator, but it requires tracking on the
838 side if we want to ensure that blocks are only read or written once. LFSR
839 guarantees that we never generate the same offset twice, and it's also less
840 computationally expensive. It's not a true random generator, however, though
841 for IO purposes it's typically good enough. LFSR only works with single block
842 sizes, not with workloads that use multiple block sizes. If used with such a
843 workload, fio may read or write some blocks multiple times.
846 Run job with given nice value. See \fBnice\fR\|(2).
849 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
852 .BI prioclass \fR=\fPint
853 Set I/O priority class. See \fBionice\fR\|(1).
855 .BI thinktime \fR=\fPint
856 Stall job for given number of microseconds between issuing I/Os.
858 .BI thinktime_spin \fR=\fPint
859 Pretend to spend CPU time for given number of microseconds, sleeping the rest
860 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
862 .BI thinktime_blocks \fR=\fPint
863 Only valid if thinktime is set - control how many blocks to issue, before
864 waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
865 make fio wait \fBthinktime\fR microseconds after every block. This
866 effectively makes any queue depth setting redundant, since no more than 1 IO
867 will be queued before we have to complete it and do our thinktime. In other
868 words, this setting effectively caps the queue depth if the latter is larger.
872 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
873 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
874 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
875 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
876 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
877 limit writes (to 500KB/sec), the latter will only limit reads.
879 .BI ratemin \fR=\fPint
880 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
881 Failing to meet this requirement will cause the job to exit. The same format
882 as \fBrate\fR is used for read vs write separation.
884 .BI rate_iops \fR=\fPint
885 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
886 specified independently of bandwidth. The same format as \fBrate\fR is used for
887 read vs write separation. If \fBblocksize\fR is a range, the smallest block
888 size is used as the metric.
890 .BI rate_iops_min \fR=\fPint
891 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
892 is used for read vs write separation.
894 .BI ratecycle \fR=\fPint
895 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
896 milliseconds. Default: 1000ms.
898 .BI latency_target \fR=\fPint
899 If set, fio will attempt to find the max performance point that the given
900 workload will run at while maintaining a latency below this target. The
901 values is given in microseconds. See \fBlatency_window\fR and
902 \fBlatency_percentile\fR.
904 .BI latency_window \fR=\fPint
905 Used with \fBlatency_target\fR to specify the sample window that the job
906 is run at varying queue depths to test the performance. The value is given
909 .BI latency_percentile \fR=\fPfloat
910 The percentage of IOs that must fall within the criteria specified by
911 \fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
912 to 100.0, meaning that all IOs must be equal or below to the value set
913 by \fBlatency_target\fR.
915 .BI max_latency \fR=\fPint
916 If set, fio will exit the job if it exceeds this maximum latency. It will exit
919 .BI cpumask \fR=\fPint
920 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
921 may run on. See \fBsched_setaffinity\fR\|(2).
923 .BI cpus_allowed \fR=\fPstr
924 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
926 .BI cpus_allowed_policy \fR=\fPstr
927 Set the policy of how fio distributes the CPUs specified by \fBcpus_allowed\fR
928 or \fBcpumask\fR. Two policies are supported:
933 All jobs will share the CPU set specified.
936 Each job will get a unique CPU from the CPU set.
939 \fBshared\fR is the default behaviour, if the option isn't specified. If
940 \fBsplit\fR is specified, then fio will assign one cpu per job. If not enough
941 CPUs are given for the jobs listed, then fio will roundrobin the CPUs in
946 .BI numa_cpu_nodes \fR=\fPstr
947 Set this job running on specified NUMA nodes' CPUs. The arguments allow
948 comma delimited list of cpu numbers, A-B ranges, or 'all'.
950 .BI numa_mem_policy \fR=\fPstr
951 Set this job's memory policy and corresponding NUMA nodes. Format of
955 .B <mode>[:<nodelist>]
958 is one of the following memory policy:
960 .B default, prefer, bind, interleave, local
963 For \fBdefault\fR and \fBlocal\fR memory policy, no \fBnodelist\fR is
964 needed to be specified. For \fBprefer\fR, only one node is
965 allowed. For \fBbind\fR and \fBinterleave\fR, \fBnodelist\fR allows
966 comma delimited list of numbers, A-B ranges, or 'all'.
968 .BI startdelay \fR=\fPirange
969 Delay start of job for the specified number of seconds. Supports all time
970 suffixes to allow specification of hours, minutes, seconds and
971 milliseconds - seconds are the default if a unit is omitted.
972 Can be given as a range which causes each thread to choose randomly out of the
975 .BI runtime \fR=\fPint
976 Terminate processing after the specified number of seconds.
979 If given, run for the specified \fBruntime\fR duration even if the files are
980 completely read or written. The same workload will be repeated as many times
981 as \fBruntime\fR allows.
983 .BI ramp_time \fR=\fPint
984 If set, fio will run the specified workload for this amount of time before
985 logging any performance numbers. Useful for letting performance settle before
986 logging results, thus minimizing the runtime required for stable results. Note
987 that the \fBramp_time\fR is considered lead in time for a job, thus it will
988 increase the total runtime if a special timeout or runtime is specified.
990 .BI invalidate \fR=\fPbool
991 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
994 Use synchronous I/O for buffered writes. For the majority of I/O engines,
995 this means using O_SYNC. Default: false.
997 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
998 Allocation method for I/O unit buffer. Allowed values are:
1003 Allocate memory with \fBmalloc\fR\|(3).
1006 Use shared memory buffers allocated through \fBshmget\fR\|(2).
1009 Same as \fBshm\fR, but use huge pages as backing.
1012 Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
1013 is given after the option in the format `:\fIfile\fR'.
1016 Same as \fBmmap\fR, but use huge files as backing.
1019 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
1020 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
1021 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
1022 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
1023 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
1024 and the documentation for that. Normally you just need to echo an appropriate
1025 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
1029 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
1030 This indicates the memory alignment of the IO memory buffers. Note that the
1031 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
1032 the alignment of the following buffers are given by the \fBbs\fR used. In
1033 other words, if using a \fBbs\fR that is a multiple of the page sized in the
1034 system, all buffers will be aligned to this value. If using a \fBbs\fR that
1035 is not page aligned, the alignment of subsequent IO memory buffers is the
1036 sum of the \fBiomem_align\fR and \fBbs\fR used.
1038 .BI hugepage\-size \fR=\fPint
1039 Defines the size of a huge page. Must be at least equal to the system setting.
1040 Should be a multiple of 1MB. Default: 4MB.
1043 Terminate all jobs when one finishes. Default: wait for each job to finish.
1045 .BI bwavgtime \fR=\fPint
1046 Average bandwidth calculations over the given time in milliseconds. Default:
1049 .BI iopsavgtime \fR=\fPint
1050 Average IOPS calculations over the given time in milliseconds. Default:
1053 .BI create_serialize \fR=\fPbool
1054 If true, serialize file creation for the jobs. Default: true.
1056 .BI create_fsync \fR=\fPbool
1057 \fBfsync\fR\|(2) data file after creation. Default: true.
1059 .BI create_on_open \fR=\fPbool
1060 If true, the files are not created until they are opened for IO by the job.
1062 .BI create_only \fR=\fPbool
1063 If true, fio will only run the setup phase of the job. If files need to be
1064 laid out or updated on disk, only that will be done. The actual job contents
1067 .BI pre_read \fR=\fPbool
1068 If this is given, files will be pre-read into memory before starting the given
1069 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
1070 pointless to pre-read and then drop the cache. This will only work for IO
1071 engines that are seekable, since they allow you to read the same data
1072 multiple times. Thus it will not work on eg network or splice IO.
1074 .BI unlink \fR=\fPbool
1075 Unlink job files when done. Default: false.
1077 .BI loops \fR=\fPint
1078 Specifies the number of iterations (runs of the same workload) of this job.
1081 .BI verify_only \fR=\fPbool
1082 Do not perform the specified workload, only verify data still matches previous
1083 invocation of this workload. This option allows one to check data multiple
1084 times at a later date without overwriting it. This option makes sense only for
1085 workloads that write data, and does not support workloads with the
1086 \fBtime_based\fR option set.
1088 .BI do_verify \fR=\fPbool
1089 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
1092 .BI verify \fR=\fPstr
1093 Method of verifying file contents after each iteration of the job. Allowed
1098 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1 xxhash
1099 Store appropriate checksum in the header of each block. crc32c-intel is
1100 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
1101 not supported by the system.
1104 Write extra information about each I/O (timestamp, block number, etc.). The
1105 block number is verified. See \fBverify_pattern\fR as well.
1108 Pretend to verify. Used for testing internals.
1111 This option can be used for repeated burn-in tests of a system to make sure
1112 that the written data is also correctly read back. If the data direction given
1113 is a read or random read, fio will assume that it should verify a previously
1114 written file. If the data direction includes any form of write, the verify will
1115 be of the newly written data.
1118 .BI verifysort \fR=\fPbool
1119 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
1120 read them back in a sorted manner. Default: true.
1122 .BI verifysort_nr \fR=\fPint
1123 Pre-load and sort verify blocks for a read workload.
1125 .BI verify_offset \fR=\fPint
1126 Swap the verification header with data somewhere else in the block before
1127 writing. It is swapped back before verifying.
1129 .BI verify_interval \fR=\fPint
1130 Write the verification header for this number of bytes, which should divide
1131 \fBblocksize\fR. Default: \fBblocksize\fR.
1133 .BI verify_pattern \fR=\fPstr
1134 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
1135 with totally random bytes, but sometimes it's interesting to fill with a known
1136 pattern for io verification purposes. Depending on the width of the pattern,
1137 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
1138 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
1139 has to be a hex number that starts with either "0x" or "0X". Use with
1142 .BI verify_fatal \fR=\fPbool
1143 If true, exit the job on the first observed verification failure. Default:
1146 .BI verify_dump \fR=\fPbool
1147 If set, dump the contents of both the original data block and the data block we
1148 read off disk to files. This allows later analysis to inspect just what kind of
1149 data corruption occurred. Off by default.
1151 .BI verify_async \fR=\fPint
1152 Fio will normally verify IO inline from the submitting thread. This option
1153 takes an integer describing how many async offload threads to create for IO
1154 verification instead, causing fio to offload the duty of verifying IO contents
1155 to one or more separate threads. If using this offload option, even sync IO
1156 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
1157 allows them to have IO in flight while verifies are running.
1159 .BI verify_async_cpus \fR=\fPstr
1160 Tell fio to set the given CPU affinity on the async IO verification threads.
1161 See \fBcpus_allowed\fP for the format used.
1163 .BI verify_backlog \fR=\fPint
1164 Fio will normally verify the written contents of a job that utilizes verify
1165 once that job has completed. In other words, everything is written then
1166 everything is read back and verified. You may want to verify continually
1167 instead for a variety of reasons. Fio stores the meta data associated with an
1168 IO block in memory, so for large verify workloads, quite a bit of memory would
1169 be used up holding this meta data. If this option is enabled, fio will write
1170 only N blocks before verifying these blocks.
1172 .BI verify_backlog_batch \fR=\fPint
1173 Control how many blocks fio will verify if verify_backlog is set. If not set,
1174 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
1175 read back and verified). If \fBverify_backlog_batch\fR is less than
1176 \fBverify_backlog\fR then not all blocks will be verified, if
1177 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
1178 will be verified more than once.
1180 .BI trim_percentage \fR=\fPint
1181 Number of verify blocks to discard/trim.
1183 .BI trim_verify_zero \fR=\fPbool
1184 Verify that trim/discarded blocks are returned as zeroes.
1186 .BI trim_backlog \fR=\fPint
1187 Trim after this number of blocks are written.
1189 .BI trim_backlog_batch \fR=\fPint
1190 Trim this number of IO blocks.
1192 .BI experimental_verify \fR=\fPbool
1193 Enable experimental verification.
1195 .BI verify_state_save \fR=\fPbool
1196 When a job exits during the write phase of a verify workload, save its
1197 current state. This allows fio to replay up until that point, if the
1198 verify state is loaded for the verify read phase.
1200 .BI verify_state_load \fR=\fPbool
1201 If a verify termination trigger was used, fio stores the current write
1202 state of each thread. This can be used at verification time so that fio
1203 knows how far it should verify. Without this information, fio will run
1204 a full verification pass, according to the settings in the job file used.
1206 .B stonewall "\fR,\fP wait_for_previous"
1207 Wait for preceding jobs in the job file to exit before starting this one.
1208 \fBstonewall\fR implies \fBnew_group\fR.
1211 Start a new reporting group. If not given, all jobs in a file will be part
1212 of the same reporting group, unless separated by a stonewall.
1214 .BI numjobs \fR=\fPint
1215 Number of clones (processes/threads performing the same workload) of this job.
1219 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
1223 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
1224 with \fBfork\fR\|(2).
1226 .BI zonesize \fR=\fPint
1227 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
1229 .BI zonerange \fR=\fPint
1230 Give size of an IO zone. See \fBzoneskip\fR.
1232 .BI zoneskip \fR=\fPint
1233 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
1236 .BI write_iolog \fR=\fPstr
1237 Write the issued I/O patterns to the specified file. Specify a separate file
1238 for each job, otherwise the iologs will be interspersed and the file may be
1241 .BI read_iolog \fR=\fPstr
1242 Replay the I/O patterns contained in the specified file generated by
1243 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
1245 .BI replay_no_stall \fR=\fPint
1246 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1247 attempts to respect timing information between I/Os. Enabling
1248 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
1249 still respecting ordering.
1251 .BI replay_redirect \fR=\fPstr
1252 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1253 is to replay the IOPS onto the major/minor device that each IOP was recorded
1254 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
1255 single specified device regardless of the device it was recorded from.
1257 .BI write_bw_log \fR=\fPstr
1258 If given, write a bandwidth log of the jobs in this job file. Can be used to
1259 store data of the bandwidth of the jobs in their lifetime. The included
1260 fio_generate_plots script uses gnuplot to turn these text files into nice
1261 graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
1262 option, the postfix is _bw.x.log, where x is the index of the job (1..N,
1263 where N is the number of jobs)
1265 .BI write_lat_log \fR=\fPstr
1266 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
1267 filename is given with this option, the default filename of
1268 "jobname_type.x.log" is used, where x is the index of the job (1..N, where
1269 N is the number of jobs). Even if the filename is given, fio will still
1270 append the type of log.
1272 .BI write_iops_log \fR=\fPstr
1273 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
1274 option, the default filename of "jobname_type.x.log" is used, where x is the
1275 index of the job (1..N, where N is the number of jobs). Even if the filename
1276 is given, fio will still append the type of log.
1278 .BI log_avg_msec \fR=\fPint
1279 By default, fio will log an entry in the iops, latency, or bw log for every
1280 IO that completes. When writing to the disk log, that can quickly grow to a
1281 very large size. Setting this option makes fio average the each log entry
1282 over the specified period of time, reducing the resolution of the log.
1285 .BI log_offset \fR=\fPbool
1286 If this is set, the iolog options will include the byte offset for the IO
1287 entry as well as the other data values.
1289 .BI log_compression \fR=\fPint
1290 If this is set, fio will compress the IO logs as it goes, to keep the memory
1291 footprint lower. When a log reaches the specified size, that chunk is removed
1292 and compressed in the background. Given that IO logs are fairly highly
1293 compressible, this yields a nice memory savings for longer runs. The downside
1294 is that the compression will consume some background CPU cycles, so it may
1295 impact the run. This, however, is also true if the logging ends up consuming
1296 most of the system memory. So pick your poison. The IO logs are saved
1297 normally at the end of a run, by decompressing the chunks and storing them
1298 in the specified log file. This feature depends on the availability of zlib.
1300 .BI log_store_compressed \fR=\fPbool
1301 If set, and \fBlog\fR_compression is also set, fio will store the log files in
1302 a compressed format. They can be decompressed with fio, using the
1303 \fB\-\-inflate-log\fR command line parameter. The files will be stored with a
1306 .BI block_error_percentiles \fR=\fPbool
1307 If set, record errors in trim block-sized units from writes and trims and output
1308 a histogram of how many trims it took to get to errors, and what kind of error
1311 .BI disable_lat \fR=\fPbool
1312 Disable measurements of total latency numbers. Useful only for cutting
1313 back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
1314 really high IOPS rates. Note that to really get rid of a large amount of these
1315 calls, this option must be used with disable_slat and disable_bw as well.
1317 .BI disable_clat \fR=\fPbool
1318 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
1320 .BI disable_slat \fR=\fPbool
1321 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
1323 .BI disable_bw_measurement \fR=\fPbool
1324 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
1326 .BI lockmem \fR=\fPint
1327 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
1328 simulate a smaller amount of memory. The amount specified is per worker.
1330 .BI exec_prerun \fR=\fPstr
1331 Before running the job, execute the specified command with \fBsystem\fR\|(3).
1333 Output is redirected in a file called \fBjobname.prerun.txt\fR
1336 .BI exec_postrun \fR=\fPstr
1337 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
1339 Output is redirected in a file called \fBjobname.postrun.txt\fR
1342 .BI ioscheduler \fR=\fPstr
1343 Attempt to switch the device hosting the file to the specified I/O scheduler.
1345 .BI disk_util \fR=\fPbool
1346 Generate disk utilization statistics if the platform supports it. Default: true.
1348 .BI clocksource \fR=\fPstr
1349 Use the given clocksource as the base of timing. The supported options are:
1353 \fBgettimeofday\fR\|(2)
1356 \fBclock_gettime\fR\|(2)
1359 Internal CPU clock source
1363 \fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
1364 (and fio is heavy on time calls). Fio will automatically use this clocksource
1365 if it's supported and considered reliable on the system it is running on,
1366 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
1367 means supporting TSC Invariant.
1369 .BI gtod_reduce \fR=\fPbool
1370 Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
1371 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
1372 \fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
1373 the gtod() calls we would have done if all time keeping was enabled.
1375 .BI gtod_cpu \fR=\fPint
1376 Sometimes it's cheaper to dedicate a single thread of execution to just getting
1377 the current time. Fio (and databases, for instance) are very intensive on
1378 \fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
1379 nothing but logging current time to a shared memory location. Then the other
1380 threads/processes that run IO workloads need only copy that segment, instead of
1381 entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
1382 these time calls will be excluded from other uses. Fio will manually clear it
1383 from the CPU mask of other jobs.
1385 .BI ignore_error \fR=\fPstr
1386 Sometimes you want to ignore some errors during test in that case you can specify
1387 error list for each error type.
1389 ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
1391 errors for given error type is separated with ':'.
1392 Error may be symbol ('ENOSPC', 'ENOMEM') or an integer.
1394 Example: ignore_error=EAGAIN,ENOSPC:122 .
1396 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from WRITE.
1398 .BI error_dump \fR=\fPbool
1399 If set dump every error even if it is non fatal, true by default. If disabled
1400 only fatal error will be dumped
1402 .BI profile \fR=\fPstr
1403 Select a specific builtin performance test.
1405 .BI cgroup \fR=\fPstr
1406 Add job to this control group. If it doesn't exist, it will be created.
1407 The system must have a mounted cgroup blkio mount point for this to work. If
1408 your system doesn't have it mounted, you can do so with:
1410 # mount \-t cgroup \-o blkio none /cgroup
1412 .BI cgroup_weight \fR=\fPint
1413 Set the weight of the cgroup to this value. See the documentation that comes
1414 with the kernel, allowed values are in the range of 100..1000.
1416 .BI cgroup_nodelete \fR=\fPbool
1417 Normally fio will delete the cgroups it has created after the job completion.
1418 To override this behavior and to leave cgroups around after the job completion,
1419 set cgroup_nodelete=1. This can be useful if one wants to inspect various
1420 cgroup files after job completion. Default: false
1423 Instead of running as the invoking user, set the user ID to this value before
1424 the thread/process does any work.
1427 Set group ID, see \fBuid\fR.
1429 .BI unit_base \fR=\fPint
1430 Base unit for reporting. Allowed values are:
1434 Use auto-detection (default).
1444 .BI flow_id \fR=\fPint
1445 The ID of the flow. If not specified, it defaults to being a global flow. See
1449 Weight in token-based flow control. If this value is used, then there is a
1450 \fBflow counter\fR which is used to regulate the proportion of activity between
1451 two or more jobs. fio attempts to keep this flow counter near zero. The
1452 \fBflow\fR parameter stands for how much should be added or subtracted to the
1453 flow counter on each iteration of the main I/O loop. That is, if one job has
1454 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
1455 1:8 ratio in how much one runs vs the other.
1457 .BI flow_watermark \fR=\fPint
1458 The maximum value that the absolute value of the flow counter is allowed to
1459 reach before the job must wait for a lower value of the counter.
1461 .BI flow_sleep \fR=\fPint
1462 The period of time, in microseconds, to wait after the flow watermark has been
1463 exceeded before retrying operations
1465 .BI clat_percentiles \fR=\fPbool
1466 Enable the reporting of percentiles of completion latencies.
1468 .BI percentile_list \fR=\fPfloat_list
1469 Overwrite the default list of percentiles for completion latencies and the
1470 block error histogram. Each number is a floating number in the range (0,100],
1471 and the maximum length of the list is 20. Use ':' to separate the
1472 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1473 report the values of completion latency below which 99.5% and 99.9% of
1474 the observed latencies fell, respectively.
1475 .SS "Ioengine Parameters List"
1476 Some parameters are only valid when a specific ioengine is in use. These are
1477 used identically to normal parameters, with the caveat that when used on the
1478 command line, they must come after the ioengine.
1480 .BI (cpu)cpuload \fR=\fPint
1481 Attempt to use the specified percentage of CPU cycles.
1483 .BI (cpu)cpuchunks \fR=\fPint
1484 Split the load into cycles of the given time. In microseconds.
1486 .BI (cpu)exit_on_io_done \fR=\fPbool
1487 Detect when IO threads are done, then exit.
1489 .BI (libaio)userspace_reap
1490 Normally, with the libaio engine in use, fio will use
1491 the io_getevents system call to reap newly returned events.
1492 With this flag turned on, the AIO ring will be read directly
1493 from user-space to reap events. The reaping mode is only
1494 enabled when polling for a minimum of 0 events (eg when
1495 iodepth_batch_complete=0).
1497 .BI (net,netsplice)hostname \fR=\fPstr
1498 The host name or IP address to use for TCP or UDP based IO.
1499 If the job is a TCP listener or UDP reader, the hostname is not
1500 used and must be omitted unless it is a valid UDP multicast address.
1502 .BI (net,netsplice)port \fR=\fPint
1503 The TCP or UDP port to bind to or connect to. If this is used with
1504 \fBnumjobs\fR to spawn multiple instances of the same job type, then
1505 this will be the starting port number since fio will use a range of ports.
1507 .BI (net,netsplice)interface \fR=\fPstr
1508 The IP address of the network interface used to send or receive UDP multicast
1511 .BI (net,netsplice)ttl \fR=\fPint
1512 Time-to-live value for outgoing UDP multicast packets. Default: 1
1514 .BI (net,netsplice)nodelay \fR=\fPbool
1515 Set TCP_NODELAY on TCP connections.
1517 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1518 The network protocol to use. Accepted values are:
1523 Transmission control protocol
1526 Transmission control protocol V6
1529 User datagram protocol
1532 User datagram protocol V6
1538 When the protocol is TCP or UDP, the port must also be given,
1539 as well as the hostname if the job is a TCP listener or UDP
1540 reader. For unix sockets, the normal filename option should be
1541 used and the port is invalid.
1544 .BI (net,netsplice)listen
1545 For TCP network connections, tell fio to listen for incoming
1546 connections rather than initiating an outgoing connection. The
1547 hostname must be omitted if this option is used.
1549 .BI (net, pingpong) \fR=\fPbool
1550 Normally a network writer will just continue writing data, and a network reader
1551 will just consume packets. If pingpong=1 is set, a writer will send its normal
1552 payload to the reader, then wait for the reader to send the same payload back.
1553 This allows fio to measure network latencies. The submission and completion
1554 latencies then measure local time spent sending or receiving, and the
1555 completion latency measures how long it took for the other end to receive and
1556 send back. For UDP multicast traffic pingpong=1 should only be set for a single
1557 reader when multiple readers are listening to the same address.
1559 .BI (net, window_size) \fR=\fPint
1560 Set the desired socket buffer size for the connection.
1562 .BI (net, mss) \fR=\fPint
1563 Set the TCP maximum segment size (TCP_MAXSEG).
1565 .BI (e4defrag,donorname) \fR=\fPstr
1566 File will be used as a block donor (swap extents between files)
1568 .BI (e4defrag,inplace) \fR=\fPint
1569 Configure donor file block allocation strategy
1572 Preallocate donor's file on init
1575 allocate space immediately inside defragment event, and free right after event
1578 .BI (rbd)rbdname \fR=\fPstr
1579 Specifies the name of the RBD.
1581 .BI (rbd)pool \fR=\fPstr
1582 Specifies the name of the Ceph pool containing the RBD.
1584 .BI (rbd)clientname \fR=\fPstr
1585 Specifies the username (without the 'client.' prefix) used to access the Ceph cluster.
1587 .BI (mtd)skipbad \fR=\fPbool
1588 Skip operations against known bad blocks.
1590 While running, \fBfio\fR will display the status of the created jobs. For
1594 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1597 The characters in the first set of brackets denote the current status of each
1598 threads. The possible values are:
1604 Setup but not started.
1610 Initialized, waiting.
1613 Running, doing sequential reads.
1616 Running, doing random reads.
1619 Running, doing sequential writes.
1622 Running, doing random writes.
1625 Running, doing mixed sequential reads/writes.
1628 Running, doing mixed random reads/writes.
1631 Running, currently waiting for \fBfsync\fR\|(2).
1634 Running, verifying written data.
1637 Exited, not reaped by main thread.
1640 Exited, thread reaped.
1644 The second set of brackets shows the estimated completion percentage of
1645 the current group. The third set shows the read and write I/O rate,
1646 respectively. Finally, the estimated run time of the job is displayed.
1648 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1649 for each thread, each group of threads, and each disk, in that order.
1651 Per-thread statistics first show the threads client number, group-id, and
1652 error code. The remaining figures are as follows:
1656 Number of megabytes of I/O performed.
1659 Average data rate (bandwidth).
1665 Submission latency minimum, maximum, average and standard deviation. This is
1666 the time it took to submit the I/O.
1669 Completion latency minimum, maximum, average and standard deviation. This
1670 is the time between submission and completion.
1673 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1674 and standard deviation.
1677 CPU usage statistics. Includes user and system time, number of context switches
1678 this thread went through and number of major and minor page faults.
1681 Distribution of I/O depths. Each depth includes everything less than (or equal)
1682 to it, but greater than the previous depth.
1685 Number of read/write requests issued, and number of short read/write requests.
1688 Distribution of I/O completion latencies. The numbers follow the same pattern
1692 The group statistics show:
1697 Number of megabytes I/O performed.
1700 Aggregate bandwidth of threads in the group.
1703 Minimum average bandwidth a thread saw.
1706 Maximum average bandwidth a thread saw.
1709 Shortest runtime of threads in the group.
1712 Longest runtime of threads in the group.
1716 Finally, disk statistics are printed with reads first:
1721 Number of I/Os performed by all groups.
1724 Number of merges in the I/O scheduler.
1727 Number of ticks we kept the disk busy.
1730 Total time spent in the disk queue.
1737 It is also possible to get fio to dump the current output while it is
1738 running, without terminating the job. To do that, send fio the \fBUSR1\fR
1741 If the \fB\-\-minimal\fR / \fB\-\-append-terse\fR options are given, the
1742 results will be printed/appended in a semicolon-delimited format suitable for
1744 A job description (if provided) follows on a new line. Note that the first
1745 number in the line is the version number. If the output has to be changed
1746 for some reason, this number will be incremented by 1 to signify that
1747 change. The fields are:
1750 .B terse version, fio version, jobname, groupid, error
1754 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1758 .B min, max, mean, standard deviation
1762 .B min, max, mean, standard deviation
1764 Completion latency percentiles (20 fields):
1766 .B Xth percentile=usec
1770 .B min, max, mean, standard deviation
1774 .B min, max, aggregate percentage of total, mean, standard deviation
1780 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1784 .B min, max, mean, standard deviation
1788 .B min, max, mean, standard deviation
1790 Completion latency percentiles (20 fields):
1792 .B Xth percentile=usec
1796 .B min, max, mean, standard deviation
1800 .B min, max, aggregate percentage of total, mean, standard deviation
1806 .B user, system, context switches, major page faults, minor page faults
1809 IO depth distribution:
1811 .B <=1, 2, 4, 8, 16, 32, >=64
1814 IO latency distribution:
1818 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1822 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1826 Disk utilization (1 for each disk used):
1828 .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
1831 Error Info (dependent on continue_on_error, default off):
1833 .B total # errors, first error code
1836 .B text description (if provided in config - appears on newline)
1839 Normally you would run fio as a stand-alone application on the machine
1840 where the IO workload should be generated. However, it is also possible to
1841 run the frontend and backend of fio separately. This makes it possible to
1842 have a fio server running on the machine(s) where the IO workload should
1843 be running, while controlling it from another machine.
1845 To start the server, you would do:
1847 \fBfio \-\-server=args\fR
1849 on that machine, where args defines what fio listens to. The arguments
1850 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1851 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain
1852 socket. 'hostname' is either a hostname or IP address, and 'port' is the port to
1853 listen to (only valid for TCP/IP, not a local socket). Some examples:
1857 Start a fio server, listening on all interfaces on the default port (8765).
1859 2) fio \-\-server=ip:hostname,4444
1861 Start a fio server, listening on IP belonging to hostname and on port 4444.
1863 3) fio \-\-server=ip6:::1,4444
1865 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1867 4) fio \-\-server=,4444
1869 Start a fio server, listening on all interfaces on port 4444.
1871 5) fio \-\-server=1.2.3.4
1873 Start a fio server, listening on IP 1.2.3.4 on the default port.
1875 6) fio \-\-server=sock:/tmp/fio.sock
1877 Start a fio server, listening on the local socket /tmp/fio.sock.
1879 When a server is running, you can connect to it from a client. The client
1882 fio \-\-local-args \-\-client=server \-\-remote-args <job file(s)>
1884 where \-\-local-args are arguments that are local to the client where it is
1885 running, 'server' is the connect string, and \-\-remote-args and <job file(s)>
1886 are sent to the server. The 'server' string follows the same format as it
1887 does on the server side, to allow IP/hostname/socket and port strings.
1888 You can connect to multiple clients as well, to do that you could run:
1890 fio \-\-client=server2 \-\-client=server2 <job file(s)>
1892 If the job file is located on the fio server, then you can tell the server
1893 to load a local file as well. This is done by using \-\-remote-config:
1895 fio \-\-client=server \-\-remote-config /path/to/file.fio
1897 Then the fio serer will open this local (to the server) job file instead
1898 of being passed one from the client.
1902 was written by Jens Axboe <jens.axboe@oracle.com>,
1903 now Jens Axboe <axboe@fb.com>.
1905 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1906 on documentation by Jens Axboe.
1907 .SH "REPORTING BUGS"
1908 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1911 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1913 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob