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
483 .BI nrfiles \fR=\fPint
484 Number of files to use for this job. Default: 1.
486 .BI openfiles \fR=\fPint
487 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
489 .BI file_service_type \fR=\fPstr
490 Defines how files to service are selected. The following types are defined:
495 Choose a file at random.
498 Round robin over opened files (default).
501 Do each file in the set sequentially.
504 The number of I/Os to issue before switching to a new file can be specified by
505 appending `:\fIint\fR' to the service type.
508 .BI ioengine \fR=\fPstr
509 Defines how the job issues I/O. The following types are defined:
514 Basic \fBread\fR\|(2) or \fBwrite\fR\|(2) I/O. \fBfseek\fR\|(2) is used to
515 position the I/O location.
518 Basic \fBpread\fR\|(2) or \fBpwrite\fR\|(2) I/O.
521 Basic \fBreadv\fR\|(2) or \fBwritev\fR\|(2) I/O. Will emulate queuing by
522 coalescing adjacent IOs into a single submission.
525 Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
528 Linux native asynchronous I/O. This ioengine defines engine specific options.
531 POSIX asynchronous I/O using \fBaio_read\fR\|(3) and \fBaio_write\fR\|(3).
534 Solaris native asynchronous I/O.
537 Windows native asynchronous I/O.
540 File is memory mapped with \fBmmap\fR\|(2) and data copied using
544 \fBsplice\fR\|(2) is used to transfer the data and \fBvmsplice\fR\|(2) to
545 transfer data from user-space to the kernel.
548 Use the syslet system calls to make regular read/write asynchronous.
551 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
552 the target is an sg character device, we use \fBread\fR\|(2) and
553 \fBwrite\fR\|(2) for asynchronous I/O.
556 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
557 itself and for debugging and testing purposes.
560 Transfer over the network. The protocol to be used can be defined with the
561 \fBprotocol\fR parameter. Depending on the protocol, \fBfilename\fR,
562 \fBhostname\fR, \fBport\fR, or \fBlisten\fR must be specified.
563 This ioengine defines engine specific options.
566 Like \fBnet\fR, but uses \fBsplice\fR\|(2) and \fBvmsplice\fR\|(2) to map data
567 and send/receive. This ioengine defines engine specific options.
570 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
571 \fBcpucycles\fR parameters.
574 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
575 approach to asynchronous I/O.
577 See <http://www.xmailserver.org/guasi\-lib.html>.
580 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
581 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
584 Loads an external I/O engine object file. Append the engine filename as
588 IO engine that does regular linux native fallocate call to simulate data
589 transfer as fio ioengine
591 DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
593 DIR_WRITE does fallocate(,mode = 0)
595 DDIR_TRIM does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)
598 IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
599 request to DDIR_WRITE event
602 IO engine supporting direct access to Ceph Rados Block Devices (RBD) via librbd
603 without the need to use the kernel rbd driver. This ioengine defines engine specific
607 Using Glusterfs libgfapi sync interface to direct access to Glusterfs volumes without
608 having to go through FUSE. This ioengine defines engine specific
612 Using Glusterfs libgfapi async interface to direct access to Glusterfs volumes without
613 having to go through FUSE. This ioengine defines engine specific
619 .BI iodepth \fR=\fPint
620 Number of I/O units to keep in flight against the file. Note that increasing
621 iodepth beyond 1 will not affect synchronous ioengines (except for small
622 degress when verify_async is in use). Even async engines may impose OS
623 restrictions causing the desired depth not to be achieved. This may happen on
624 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
625 not async on that OS. Keep an eye on the IO depth distribution in the
626 fio output to verify that the achieved depth is as expected. Default: 1.
628 .BI iodepth_batch \fR=\fPint
629 Number of I/Os to submit at once. Default: \fBiodepth\fR.
631 .BI iodepth_batch_complete \fR=\fPint
632 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
633 means that we'll ask for a minimum of 1 IO in the retrieval process from the
634 kernel. The IO retrieval will go on until we hit the limit set by
635 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
636 completed events before queuing more IO. This helps reduce IO latency, at the
637 cost of more retrieval system calls.
639 .BI iodepth_low \fR=\fPint
640 Low watermark indicating when to start filling the queue again. Default:
643 .BI direct \fR=\fPbool
644 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
646 .BI atomic \fR=\fPbool
647 If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
648 to be stable once acknowledged by the operating system. Only Linux supports
651 .BI buffered \fR=\fPbool
652 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
655 .BI offset \fR=\fPint
656 Offset in the file to start I/O. Data before the offset will not be touched.
658 .BI offset_increment \fR=\fPint
659 If this is provided, then the real offset becomes the
660 offset + offset_increment * thread_number, where the thread number is a
661 counter that starts at 0 and is incremented for each sub-job (i.e. when
662 numjobs option is specified). This option is useful if there are several jobs
663 which are intended to operate on a file in parallel disjoint segments, with
664 even spacing between the starting points.
666 .BI number_ios \fR=\fPint
667 Fio will normally perform IOs until it has exhausted the size of the region
668 set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
669 condition). With this setting, the range/size can be set independently of
670 the number of IOs to perform. When fio reaches this number, it will exit
671 normally and report status.
674 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
675 0, don't sync. Default: 0.
677 .BI fdatasync \fR=\fPint
678 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
679 data parts of the file. Default: 0.
681 .BI write_barrier \fR=\fPint
682 Make every Nth write a barrier write.
684 .BI sync_file_range \fR=\fPstr:int
685 Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
686 track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
687 \fRstr\fP can currently be one or more of:
691 SYNC_FILE_RANGE_WAIT_BEFORE
694 SYNC_FILE_RANGE_WRITE
697 SYNC_FILE_RANGE_WRITE
701 So if you do sync_file_range=wait_before,write:8, fio would use
702 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
703 Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
705 .BI overwrite \fR=\fPbool
706 If writing, setup the file first and do overwrites. Default: false.
708 .BI end_fsync \fR=\fPbool
709 Sync file contents when a write stage has completed. Default: false.
711 .BI fsync_on_close \fR=\fPbool
712 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
713 it will happen on every close, not just at the end of the job. Default: false.
715 .BI rwmixread \fR=\fPint
716 Percentage of a mixed workload that should be reads. Default: 50.
718 .BI rwmixwrite \fR=\fPint
719 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
720 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
721 overrides the first. This may interfere with a given rate setting, if fio is
722 asked to limit reads or writes to a certain rate. If that is the case, then
723 the distribution may be skewed. Default: 50.
725 .BI random_distribution \fR=\fPstr:float
726 By default, fio will use a completely uniform random distribution when asked
727 to perform random IO. Sometimes it is useful to skew the distribution in
728 specific ways, ensuring that some parts of the data is more hot than others.
729 Fio includes the following distribution models:
733 Uniform random distribution
743 When using a zipf or pareto distribution, an input value is also needed to
744 define the access pattern. For zipf, this is the zipf theta. For pareto,
745 it's the pareto power. Fio includes a test program, genzipf, that can be
746 used visualize what the given input values will yield in terms of hit rates.
747 If you wanted to use zipf with a theta of 1.2, you would use
748 random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
749 fio will disable use of the random map.
751 .BI percentage_random \fR=\fPint
752 For a random workload, set how big a percentage should be random. This defaults
753 to 100%, in which case the workload is fully random. It can be set from
754 anywhere from 0 to 100. Setting it to 0 would make the workload fully
755 sequential. It is possible to set different values for reads, writes, and
756 trim. To do so, simply use a comma separated list. See \fBblocksize\fR.
759 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
760 this parameter is given, a new offset will be chosen without looking at past
761 I/O history. This parameter is mutually exclusive with \fBverify\fR.
763 .BI softrandommap \fR=\fPbool
764 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
765 fails to allocate the map, if this option is set it will continue without a
766 random block map. As coverage will not be as complete as with random maps, this
767 option is disabled by default.
769 .BI random_generator \fR=\fPstr
770 Fio supports the following engines for generating IO offsets for random IO:
774 Strong 2^88 cycle random number generator
777 Linear feedback shift register generator
781 Tausworthe is a strong random number generator, but it requires tracking on the
782 side if we want to ensure that blocks are only read or written once. LFSR
783 guarantees that we never generate the same offset twice, and it's also less
784 computationally expensive. It's not a true random generator, however, though
785 for IO purposes it's typically good enough. LFSR only works with single block
786 sizes, not with workloads that use multiple block sizes. If used with such a
787 workload, fio may read or write some blocks multiple times.
790 Run job with given nice value. See \fBnice\fR\|(2).
793 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
796 .BI prioclass \fR=\fPint
797 Set I/O priority class. See \fBionice\fR\|(1).
799 .BI thinktime \fR=\fPint
800 Stall job for given number of microseconds between issuing I/Os.
802 .BI thinktime_spin \fR=\fPint
803 Pretend to spend CPU time for given number of microseconds, sleeping the rest
804 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
806 .BI thinktime_blocks \fR=\fPint
807 Only valid if thinktime is set - control how many blocks to issue, before
808 waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
809 make fio wait \fBthinktime\fR microseconds after every block. This
810 effectively makes any queue depth setting redundant, since no more than 1 IO
811 will be queued before we have to complete it and do our thinktime. In other
812 words, this setting effectively caps the queue depth if the latter is larger.
816 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
817 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
818 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
819 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
820 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
821 limit writes (to 500KB/sec), the latter will only limit reads.
823 .BI ratemin \fR=\fPint
824 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
825 Failing to meet this requirement will cause the job to exit. The same format
826 as \fBrate\fR is used for read vs write separation.
828 .BI rate_iops \fR=\fPint
829 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
830 specified independently of bandwidth. The same format as \fBrate\fR is used for
831 read vs write separation. If \fBblocksize\fR is a range, the smallest block
832 size is used as the metric.
834 .BI rate_iops_min \fR=\fPint
835 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
836 is used for read vs write separation.
838 .BI ratecycle \fR=\fPint
839 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
840 milliseconds. Default: 1000ms.
842 .BI latency_target \fR=\fPint
843 If set, fio will attempt to find the max performance point that the given
844 workload will run at while maintaining a latency below this target. The
845 values is given in microseconds. See \fBlatency_window\fR and
846 \fBlatency_percentile\fR.
848 .BI latency_window \fR=\fPint
849 Used with \fBlatency_target\fR to specify the sample window that the job
850 is run at varying queue depths to test the performance. The value is given
853 .BI latency_percentile \fR=\fPfloat
854 The percentage of IOs that must fall within the criteria specified by
855 \fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
856 to 100.0, meaning that all IOs must be equal or below to the value set
857 by \fBlatency_target\fR.
859 .BI max_latency \fR=\fPint
860 If set, fio will exit the job if it exceeds this maximum latency. It will exit
863 .BI cpumask \fR=\fPint
864 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
865 may run on. See \fBsched_setaffinity\fR\|(2).
867 .BI cpus_allowed \fR=\fPstr
868 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
870 .BI cpus_allowed_policy \fR=\fPstr
871 Set the policy of how fio distributes the CPUs specified by \fBcpus_allowed\fR
872 or \fBcpumask\fR. Two policies are supported:
877 All jobs will share the CPU set specified.
880 Each job will get a unique CPU from the CPU set.
883 \fBshared\fR is the default behaviour, if the option isn't specified. If
884 \fBsplit\fR is specified, then fio will assign one cpu per job. If not enough
885 CPUs are given for the jobs listed, then fio will roundrobin the CPUs in
890 .BI numa_cpu_nodes \fR=\fPstr
891 Set this job running on specified NUMA nodes' CPUs. The arguments allow
892 comma delimited list of cpu numbers, A-B ranges, or 'all'.
894 .BI numa_mem_policy \fR=\fPstr
895 Set this job's memory policy and corresponding NUMA nodes. Format of
899 .B <mode>[:<nodelist>]
902 is one of the following memory policy:
904 .B default, prefer, bind, interleave, local
907 For \fBdefault\fR and \fBlocal\fR memory policy, no \fBnodelist\fR is
908 needed to be specified. For \fBprefer\fR, only one node is
909 allowed. For \fBbind\fR and \fBinterleave\fR, \fBnodelist\fR allows
910 comma delimited list of numbers, A-B ranges, or 'all'.
912 .BI startdelay \fR=\fPirange
913 Delay start of job for the specified number of seconds. Supports all time
914 suffixes to allow specification of hours, minutes, seconds and
915 milliseconds - seconds are the default if a unit is ommited.
916 Can be given as a range which causes each thread to choose randomly out of the
919 .BI runtime \fR=\fPint
920 Terminate processing after the specified number of seconds.
923 If given, run for the specified \fBruntime\fR duration even if the files are
924 completely read or written. The same workload will be repeated as many times
925 as \fBruntime\fR allows.
927 .BI ramp_time \fR=\fPint
928 If set, fio will run the specified workload for this amount of time before
929 logging any performance numbers. Useful for letting performance settle before
930 logging results, thus minimizing the runtime required for stable results. Note
931 that the \fBramp_time\fR is considered lead in time for a job, thus it will
932 increase the total runtime if a special timeout or runtime is specified.
934 .BI invalidate \fR=\fPbool
935 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
938 Use synchronous I/O for buffered writes. For the majority of I/O engines,
939 this means using O_SYNC. Default: false.
941 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
942 Allocation method for I/O unit buffer. Allowed values are:
947 Allocate memory with \fBmalloc\fR\|(3).
950 Use shared memory buffers allocated through \fBshmget\fR\|(2).
953 Same as \fBshm\fR, but use huge pages as backing.
956 Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
957 is given after the option in the format `:\fIfile\fR'.
960 Same as \fBmmap\fR, but use huge files as backing.
963 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
964 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
965 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
966 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
967 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
968 and the documentation for that. Normally you just need to echo an appropriate
969 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
973 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
974 This indicates the memory alignment of the IO memory buffers. Note that the
975 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
976 the alignment of the following buffers are given by the \fBbs\fR used. In
977 other words, if using a \fBbs\fR that is a multiple of the page sized in the
978 system, all buffers will be aligned to this value. If using a \fBbs\fR that
979 is not page aligned, the alignment of subsequent IO memory buffers is the
980 sum of the \fBiomem_align\fR and \fBbs\fR used.
982 .BI hugepage\-size \fR=\fPint
983 Defines the size of a huge page. Must be at least equal to the system setting.
984 Should be a multiple of 1MB. Default: 4MB.
987 Terminate all jobs when one finishes. Default: wait for each job to finish.
989 .BI bwavgtime \fR=\fPint
990 Average bandwidth calculations over the given time in milliseconds. Default:
993 .BI iopsavgtime \fR=\fPint
994 Average IOPS calculations over the given time in milliseconds. Default:
997 .BI create_serialize \fR=\fPbool
998 If true, serialize file creation for the jobs. Default: true.
1000 .BI create_fsync \fR=\fPbool
1001 \fBfsync\fR\|(2) data file after creation. Default: true.
1003 .BI create_on_open \fR=\fPbool
1004 If true, the files are not created until they are opened for IO by the job.
1006 .BI create_only \fR=\fPbool
1007 If true, fio will only run the setup phase of the job. If files need to be
1008 laid out or updated on disk, only that will be done. The actual job contents
1011 .BI pre_read \fR=\fPbool
1012 If this is given, files will be pre-read into memory before starting the given
1013 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
1014 pointless to pre-read and then drop the cache. This will only work for IO
1015 engines that are seekable, since they allow you to read the same data
1016 multiple times. Thus it will not work on eg network or splice IO.
1018 .BI unlink \fR=\fPbool
1019 Unlink job files when done. Default: false.
1021 .BI loops \fR=\fPint
1022 Specifies the number of iterations (runs of the same workload) of this job.
1025 .BI verify_only \fR=\fPbool
1026 Do not perform the specified workload, only verify data still matches previous
1027 invocation of this workload. This option allows one to check data multiple
1028 times at a later date without overwriting it. This option makes sense only for
1029 workloads that write data, and does not support workloads with the
1030 \fBtime_based\fR option set.
1032 .BI do_verify \fR=\fPbool
1033 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
1036 .BI verify \fR=\fPstr
1037 Method of verifying file contents after each iteration of the job. Allowed
1042 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1 xxhash
1043 Store appropriate checksum in the header of each block. crc32c-intel is
1044 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
1045 not supported by the system.
1048 Write extra information about each I/O (timestamp, block number, etc.). The
1049 block number is verified. See \fBverify_pattern\fR as well.
1052 Pretend to verify. Used for testing internals.
1055 This option can be used for repeated burn-in tests of a system to make sure
1056 that the written data is also correctly read back. If the data direction given
1057 is a read or random read, fio will assume that it should verify a previously
1058 written file. If the data direction includes any form of write, the verify will
1059 be of the newly written data.
1062 .BI verifysort \fR=\fPbool
1063 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
1064 read them back in a sorted manner. Default: true.
1066 .BI verifysort_nr \fR=\fPint
1067 Pre-load and sort verify blocks for a read workload.
1069 .BI verify_offset \fR=\fPint
1070 Swap the verification header with data somewhere else in the block before
1071 writing. It is swapped back before verifying.
1073 .BI verify_interval \fR=\fPint
1074 Write the verification header for this number of bytes, which should divide
1075 \fBblocksize\fR. Default: \fBblocksize\fR.
1077 .BI verify_pattern \fR=\fPstr
1078 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
1079 with totally random bytes, but sometimes it's interesting to fill with a known
1080 pattern for io verification purposes. Depending on the width of the pattern,
1081 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
1082 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
1083 has to be a hex number that starts with either "0x" or "0X". Use with
1086 .BI verify_fatal \fR=\fPbool
1087 If true, exit the job on the first observed verification failure. Default:
1090 .BI verify_dump \fR=\fPbool
1091 If set, dump the contents of both the original data block and the data block we
1092 read off disk to files. This allows later analysis to inspect just what kind of
1093 data corruption occurred. Off by default.
1095 .BI verify_async \fR=\fPint
1096 Fio will normally verify IO inline from the submitting thread. This option
1097 takes an integer describing how many async offload threads to create for IO
1098 verification instead, causing fio to offload the duty of verifying IO contents
1099 to one or more separate threads. If using this offload option, even sync IO
1100 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
1101 allows them to have IO in flight while verifies are running.
1103 .BI verify_async_cpus \fR=\fPstr
1104 Tell fio to set the given CPU affinity on the async IO verification threads.
1105 See \fBcpus_allowed\fP for the format used.
1107 .BI verify_backlog \fR=\fPint
1108 Fio will normally verify the written contents of a job that utilizes verify
1109 once that job has completed. In other words, everything is written then
1110 everything is read back and verified. You may want to verify continually
1111 instead for a variety of reasons. Fio stores the meta data associated with an
1112 IO block in memory, so for large verify workloads, quite a bit of memory would
1113 be used up holding this meta data. If this option is enabled, fio will write
1114 only N blocks before verifying these blocks.
1116 .BI verify_backlog_batch \fR=\fPint
1117 Control how many blocks fio will verify if verify_backlog is set. If not set,
1118 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
1119 read back and verified). If \fBverify_backlog_batch\fR is less than
1120 \fBverify_backlog\fR then not all blocks will be verified, if
1121 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
1122 will be verified more than once.
1124 .BI trim_percentage \fR=\fPint
1125 Number of verify blocks to discard/trim.
1127 .BI trim_verify_zero \fR=\fPbool
1128 Verify that trim/discarded blocks are returned as zeroes.
1130 .BI trim_backlog \fR=\fPint
1131 Trim after this number of blocks are written.
1133 .BI trim_backlog_batch \fR=\fPint
1134 Trim this number of IO blocks.
1136 .BI experimental_verify \fR=\fPbool
1137 Enable experimental verification.
1139 .B stonewall "\fR,\fP wait_for_previous"
1140 Wait for preceding jobs in the job file to exit before starting this one.
1141 \fBstonewall\fR implies \fBnew_group\fR.
1144 Start a new reporting group. If not given, all jobs in a file will be part
1145 of the same reporting group, unless separated by a stonewall.
1147 .BI numjobs \fR=\fPint
1148 Number of clones (processes/threads performing the same workload) of this job.
1152 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
1156 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
1157 with \fBfork\fR\|(2).
1159 .BI zonesize \fR=\fPint
1160 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
1162 .BI zonerange \fR=\fPint
1163 Give size of an IO zone. See \fBzoneskip\fR.
1165 .BI zoneskip \fR=\fPint
1166 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
1169 .BI write_iolog \fR=\fPstr
1170 Write the issued I/O patterns to the specified file. Specify a separate file
1171 for each job, otherwise the iologs will be interspersed and the file may be
1174 .BI read_iolog \fR=\fPstr
1175 Replay the I/O patterns contained in the specified file generated by
1176 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
1178 .BI replay_no_stall \fR=\fPint
1179 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1180 attempts to respect timing information between I/Os. Enabling
1181 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
1182 still respecting ordering.
1184 .BI replay_redirect \fR=\fPstr
1185 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1186 is to replay the IOPS onto the major/minor device that each IOP was recorded
1187 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
1188 single specified device regardless of the device it was recorded from.
1190 .BI write_bw_log \fR=\fPstr
1191 If given, write a bandwidth log of the jobs in this job file. Can be used to
1192 store data of the bandwidth of the jobs in their lifetime. The included
1193 fio_generate_plots script uses gnuplot to turn these text files into nice
1194 graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
1195 option, the postfix is _bw.x.log, where x is the index of the job (1..N,
1196 where N is the number of jobs)
1198 .BI write_lat_log \fR=\fPstr
1199 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
1200 filename is given with this option, the default filename of
1201 "jobname_type.x.log" is used, where x is the index of the job (1..N, where
1202 N is the number of jobs). Even if the filename is given, fio will still
1203 append the type of log.
1205 .BI write_iops_log \fR=\fPstr
1206 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
1207 option, the default filename of "jobname_type.x.log" is used, where x is the
1208 index of the job (1..N, where N is the number of jobs). Even if the filename
1209 is given, fio will still append the type of log.
1211 .BI log_avg_msec \fR=\fPint
1212 By default, fio will log an entry in the iops, latency, or bw log for every
1213 IO that completes. When writing to the disk log, that can quickly grow to a
1214 very large size. Setting this option makes fio average the each log entry
1215 over the specified period of time, reducing the resolution of the log.
1218 .BI log_offset \fR=\fPbool
1219 If this is set, the iolog options will include the byte offset for the IO
1220 entry as well as the other data values.
1222 .BI log_compression \fR=\fPint
1223 If this is set, fio will compress the IO logs as it goes, to keep the memory
1224 footprint lower. When a log reaches the specified size, that chunk is removed
1225 and compressed in the background. Given that IO logs are fairly highly
1226 compressible, this yields a nice memory savings for longer runs. The downside
1227 is that the compression will consume some background CPU cycles, so it may
1228 impact the run. This, however, is also true if the logging ends up consuming
1229 most of the system memory. So pick your poison. The IO logs are saved
1230 normally at the end of a run, by decompressing the chunks and storing them
1231 in the specified log file. This feature depends on the availability of zlib.
1233 .BI log_store_compressed \fR=\fPbool
1234 If set, and \fBlog\fR_compression is also set, fio will store the log files in
1235 a compressed format. They can be decompressed with fio, using the
1236 \fB\-\-inflate-log\fR command line parameter. The files will be stored with a
1239 .BI disable_lat \fR=\fPbool
1240 Disable measurements of total latency numbers. Useful only for cutting
1241 back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
1242 really high IOPS rates. Note that to really get rid of a large amount of these
1243 calls, this option must be used with disable_slat and disable_bw as well.
1245 .BI disable_clat \fR=\fPbool
1246 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
1248 .BI disable_slat \fR=\fPbool
1249 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
1251 .BI disable_bw_measurement \fR=\fPbool
1252 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
1254 .BI lockmem \fR=\fPint
1255 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
1256 simulate a smaller amount of memory. The amount specified is per worker.
1258 .BI exec_prerun \fR=\fPstr
1259 Before running the job, execute the specified command with \fBsystem\fR\|(3).
1261 Output is redirected in a file called \fBjobname.prerun.txt\fR
1264 .BI exec_postrun \fR=\fPstr
1265 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
1267 Output is redirected in a file called \fBjobname.postrun.txt\fR
1270 .BI ioscheduler \fR=\fPstr
1271 Attempt to switch the device hosting the file to the specified I/O scheduler.
1273 .BI disk_util \fR=\fPbool
1274 Generate disk utilization statistics if the platform supports it. Default: true.
1276 .BI clocksource \fR=\fPstr
1277 Use the given clocksource as the base of timing. The supported options are:
1281 \fBgettimeofday\fR\|(2)
1284 \fBclock_gettime\fR\|(2)
1287 Internal CPU clock source
1291 \fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
1292 (and fio is heavy on time calls). Fio will automatically use this clocksource
1293 if it's supported and considered reliable on the system it is running on,
1294 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
1295 means supporting TSC Invariant.
1297 .BI gtod_reduce \fR=\fPbool
1298 Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
1299 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
1300 \fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
1301 the gtod() calls we would have done if all time keeping was enabled.
1303 .BI gtod_cpu \fR=\fPint
1304 Sometimes it's cheaper to dedicate a single thread of execution to just getting
1305 the current time. Fio (and databases, for instance) are very intensive on
1306 \fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
1307 nothing but logging current time to a shared memory location. Then the other
1308 threads/processes that run IO workloads need only copy that segment, instead of
1309 entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
1310 these time calls will be excluded from other uses. Fio will manually clear it
1311 from the CPU mask of other jobs.
1313 .BI ignore_error \fR=\fPstr
1314 Sometimes you want to ignore some errors during test in that case you can specify
1315 error list for each error type.
1317 ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
1319 errors for given error type is separated with ':'.
1320 Error may be symbol ('ENOSPC', 'ENOMEM') or an integer.
1322 Example: ignore_error=EAGAIN,ENOSPC:122 .
1324 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from WRITE.
1326 .BI error_dump \fR=\fPbool
1327 If set dump every error even if it is non fatal, true by default. If disabled
1328 only fatal error will be dumped
1330 .BI profile \fR=\fPstr
1331 Select a specific builtin performance test.
1333 .BI cgroup \fR=\fPstr
1334 Add job to this control group. If it doesn't exist, it will be created.
1335 The system must have a mounted cgroup blkio mount point for this to work. If
1336 your system doesn't have it mounted, you can do so with:
1338 # mount \-t cgroup \-o blkio none /cgroup
1340 .BI cgroup_weight \fR=\fPint
1341 Set the weight of the cgroup to this value. See the documentation that comes
1342 with the kernel, allowed values are in the range of 100..1000.
1344 .BI cgroup_nodelete \fR=\fPbool
1345 Normally fio will delete the cgroups it has created after the job completion.
1346 To override this behavior and to leave cgroups around after the job completion,
1347 set cgroup_nodelete=1. This can be useful if one wants to inspect various
1348 cgroup files after job completion. Default: false
1351 Instead of running as the invoking user, set the user ID to this value before
1352 the thread/process does any work.
1355 Set group ID, see \fBuid\fR.
1357 .BI unit_base \fR=\fPint
1358 Base unit for reporting. Allowed values are:
1362 Use auto-detection (default).
1372 .BI flow_id \fR=\fPint
1373 The ID of the flow. If not specified, it defaults to being a global flow. See
1377 Weight in token-based flow control. If this value is used, then there is a
1378 \fBflow counter\fR which is used to regulate the proportion of activity between
1379 two or more jobs. fio attempts to keep this flow counter near zero. The
1380 \fBflow\fR parameter stands for how much should be added or subtracted to the
1381 flow counter on each iteration of the main I/O loop. That is, if one job has
1382 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
1383 1:8 ratio in how much one runs vs the other.
1385 .BI flow_watermark \fR=\fPint
1386 The maximum value that the absolute value of the flow counter is allowed to
1387 reach before the job must wait for a lower value of the counter.
1389 .BI flow_sleep \fR=\fPint
1390 The period of time, in microseconds, to wait after the flow watermark has been
1391 exceeded before retrying operations
1393 .BI clat_percentiles \fR=\fPbool
1394 Enable the reporting of percentiles of completion latencies.
1396 .BI percentile_list \fR=\fPfloat_list
1397 Overwrite the default list of percentiles for completion
1398 latencies. Each number is a floating number in the range (0,100], and
1399 the maximum length of the list is 20. Use ':' to separate the
1400 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1401 report the values of completion latency below which 99.5% and 99.9% of
1402 the observed latencies fell, respectively.
1403 .SS "Ioengine Parameters List"
1404 Some parameters are only valid when a specific ioengine is in use. These are
1405 used identically to normal parameters, with the caveat that when used on the
1406 command line, they must come after the ioengine.
1408 .BI (cpu)cpuload \fR=\fPint
1409 Attempt to use the specified percentage of CPU cycles.
1411 .BI (cpu)cpuchunks \fR=\fPint
1412 Split the load into cycles of the given time. In microseconds.
1414 .BI (cpu)exit_on_io_done \fR=\fPbool
1415 Detect when IO threads are done, then exit.
1417 .BI (libaio)userspace_reap
1418 Normally, with the libaio engine in use, fio will use
1419 the io_getevents system call to reap newly returned events.
1420 With this flag turned on, the AIO ring will be read directly
1421 from user-space to reap events. The reaping mode is only
1422 enabled when polling for a minimum of 0 events (eg when
1423 iodepth_batch_complete=0).
1425 .BI (net,netsplice)hostname \fR=\fPstr
1426 The host name or IP address to use for TCP or UDP based IO.
1427 If the job is a TCP listener or UDP reader, the hostname is not
1428 used and must be omitted unless it is a valid UDP multicast address.
1430 .BI (net,netsplice)port \fR=\fPint
1431 The TCP or UDP port to bind to or connect to.
1433 .BI (net,netsplice)interface \fR=\fPstr
1434 The IP address of the network interface used to send or receive UDP multicast
1437 .BI (net,netsplice)ttl \fR=\fPint
1438 Time-to-live value for outgoing UDP multicast packets. Default: 1
1440 .BI (net,netsplice)nodelay \fR=\fPbool
1441 Set TCP_NODELAY on TCP connections.
1443 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1444 The network protocol to use. Accepted values are:
1449 Transmission control protocol
1452 Transmission control protocol V6
1455 User datagram protocol
1458 User datagram protocol V6
1464 When the protocol is TCP or UDP, the port must also be given,
1465 as well as the hostname if the job is a TCP listener or UDP
1466 reader. For unix sockets, the normal filename option should be
1467 used and the port is invalid.
1470 .BI (net,netsplice)listen
1471 For TCP network connections, tell fio to listen for incoming
1472 connections rather than initiating an outgoing connection. The
1473 hostname must be omitted if this option is used.
1475 .BI (net, pingpong) \fR=\fPbool
1476 Normally a network writer will just continue writing data, and a network reader
1477 will just consume packets. If pingpong=1 is set, a writer will send its normal
1478 payload to the reader, then wait for the reader to send the same payload back.
1479 This allows fio to measure network latencies. The submission and completion
1480 latencies then measure local time spent sending or receiving, and the
1481 completion latency measures how long it took for the other end to receive and
1482 send back. For UDP multicast traffic pingpong=1 should only be set for a single
1483 reader when multiple readers are listening to the same address.
1485 .BI (e4defrag,donorname) \fR=\fPstr
1486 File will be used as a block donor (swap extents between files)
1488 .BI (e4defrag,inplace) \fR=\fPint
1489 Configure donor file block allocation strategy
1492 Preallocate donor's file on init
1495 allocate space immediately inside defragment event, and free right after event
1498 .BI (rbd)rbdname \fR=\fPstr
1499 Specifies the name of the RBD.
1501 .BI (rbd)pool \fR=\fPstr
1502 Specifies the name of the Ceph pool containing the RBD.
1504 .BI (rbd)clientname \fR=\fPstr
1505 Specifies the username (without the 'client.' prefix) used to access the Ceph cluster.
1507 While running, \fBfio\fR will display the status of the created jobs. For
1511 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1514 The characters in the first set of brackets denote the current status of each
1515 threads. The possible values are:
1521 Setup but not started.
1527 Initialized, waiting.
1530 Running, doing sequential reads.
1533 Running, doing random reads.
1536 Running, doing sequential writes.
1539 Running, doing random writes.
1542 Running, doing mixed sequential reads/writes.
1545 Running, doing mixed random reads/writes.
1548 Running, currently waiting for \fBfsync\fR\|(2).
1551 Running, verifying written data.
1554 Exited, not reaped by main thread.
1557 Exited, thread reaped.
1561 The second set of brackets shows the estimated completion percentage of
1562 the current group. The third set shows the read and write I/O rate,
1563 respectively. Finally, the estimated run time of the job is displayed.
1565 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1566 for each thread, each group of threads, and each disk, in that order.
1568 Per-thread statistics first show the threads client number, group-id, and
1569 error code. The remaining figures are as follows:
1573 Number of megabytes of I/O performed.
1576 Average data rate (bandwidth).
1582 Submission latency minimum, maximum, average and standard deviation. This is
1583 the time it took to submit the I/O.
1586 Completion latency minimum, maximum, average and standard deviation. This
1587 is the time between submission and completion.
1590 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1591 and standard deviation.
1594 CPU usage statistics. Includes user and system time, number of context switches
1595 this thread went through and number of major and minor page faults.
1598 Distribution of I/O depths. Each depth includes everything less than (or equal)
1599 to it, but greater than the previous depth.
1602 Number of read/write requests issued, and number of short read/write requests.
1605 Distribution of I/O completion latencies. The numbers follow the same pattern
1609 The group statistics show:
1614 Number of megabytes I/O performed.
1617 Aggregate bandwidth of threads in the group.
1620 Minimum average bandwidth a thread saw.
1623 Maximum average bandwidth a thread saw.
1626 Shortest runtime of threads in the group.
1629 Longest runtime of threads in the group.
1633 Finally, disk statistics are printed with reads first:
1638 Number of I/Os performed by all groups.
1641 Number of merges in the I/O scheduler.
1644 Number of ticks we kept the disk busy.
1647 Total time spent in the disk queue.
1654 It is also possible to get fio to dump the current output while it is
1655 running, without terminating the job. To do that, send fio the \fBUSR1\fR
1658 If the \fB\-\-minimal\fR / \fB\-\-append-terse\fR options are given, the
1659 results will be printed/appended in a semicolon-delimited format suitable for
1661 A job description (if provided) follows on a new line. Note that the first
1662 number in the line is the version number. If the output has to be changed
1663 for some reason, this number will be incremented by 1 to signify that
1664 change. The fields are:
1667 .B terse version, fio version, jobname, groupid, error
1671 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1675 .B min, max, mean, standard deviation
1679 .B min, max, mean, standard deviation
1681 Completion latency percentiles (20 fields):
1683 .B Xth percentile=usec
1687 .B min, max, mean, standard deviation
1691 .B min, max, aggregate percentage of total, mean, standard deviation
1697 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1701 .B min, max, mean, standard deviation
1705 .B min, max, mean, standard deviation
1707 Completion latency percentiles (20 fields):
1709 .B Xth percentile=usec
1713 .B min, max, mean, standard deviation
1717 .B min, max, aggregate percentage of total, mean, standard deviation
1723 .B user, system, context switches, major page faults, minor page faults
1726 IO depth distribution:
1728 .B <=1, 2, 4, 8, 16, 32, >=64
1731 IO latency distribution:
1735 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1739 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1743 Disk utilization (1 for each disk used):
1745 .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
1748 Error Info (dependent on continue_on_error, default off):
1750 .B total # errors, first error code
1753 .B text description (if provided in config - appears on newline)
1756 Normally you would run fio as a stand-alone application on the machine
1757 where the IO workload should be generated. However, it is also possible to
1758 run the frontend and backend of fio separately. This makes it possible to
1759 have a fio server running on the machine(s) where the IO workload should
1760 be running, while controlling it from another machine.
1762 To start the server, you would do:
1764 \fBfio \-\-server=args\fR
1766 on that machine, where args defines what fio listens to. The arguments
1767 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1768 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain
1769 socket. 'hostname' is either a hostname or IP address, and 'port' is the port to
1770 listen to (only valid for TCP/IP, not a local socket). Some examples:
1774 Start a fio server, listening on all interfaces on the default port (8765).
1776 2) fio \-\-server=ip:hostname,4444
1778 Start a fio server, listening on IP belonging to hostname and on port 4444.
1780 3) fio \-\-server=ip6:::1,4444
1782 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1784 4) fio \-\-server=,4444
1786 Start a fio server, listening on all interfaces on port 4444.
1788 5) fio \-\-server=1.2.3.4
1790 Start a fio server, listening on IP 1.2.3.4 on the default port.
1792 6) fio \-\-server=sock:/tmp/fio.sock
1794 Start a fio server, listening on the local socket /tmp/fio.sock.
1796 When a server is running, you can connect to it from a client. The client
1799 fio \-\-local-args \-\-client=server \-\-remote-args <job file(s)>
1801 where \-\-local-args are arguments that are local to the client where it is
1802 running, 'server' is the connect string, and \-\-remote-args and <job file(s)>
1803 are sent to the server. The 'server' string follows the same format as it
1804 does on the server side, to allow IP/hostname/socket and port strings.
1805 You can connect to multiple clients as well, to do that you could run:
1807 fio \-\-client=server2 \-\-client=server2 <job file(s)>
1811 was written by Jens Axboe <jens.axboe@oracle.com>,
1812 now Jens Axboe <jaxboe@fusionio.com>.
1814 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1815 on documentation by Jens Axboe.
1816 .SH "REPORTING BUGS"
1817 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1820 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1822 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob