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
617 Read and write through Hadoop (HDFS). The \fBfilename\fR option is used to
618 specify host,port of the hdfs name-node to connect. This engine interprets
619 offsets a little differently. In HDFS, files once created cannot be modified.
620 So random writes are not possible. To imitate this, libhdfs engine expects
621 bunch of small files to be created over HDFS, and engine will randomly pick a
622 file out of those files based on the offset generated by fio backend. (see the
623 example job file to create such files, use rw=write option). Please note, you
624 might want to set necessary environment variables to work with hdfs/libhdfs
630 .BI iodepth \fR=\fPint
631 Number of I/O units to keep in flight against the file. Note that increasing
632 iodepth beyond 1 will not affect synchronous ioengines (except for small
633 degress when verify_async is in use). Even async engines may impose OS
634 restrictions causing the desired depth not to be achieved. This may happen on
635 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
636 not async on that OS. Keep an eye on the IO depth distribution in the
637 fio output to verify that the achieved depth is as expected. Default: 1.
639 .BI iodepth_batch \fR=\fPint
640 Number of I/Os to submit at once. Default: \fBiodepth\fR.
642 .BI iodepth_batch_complete \fR=\fPint
643 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
644 means that we'll ask for a minimum of 1 IO in the retrieval process from the
645 kernel. The IO retrieval will go on until we hit the limit set by
646 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
647 completed events before queuing more IO. This helps reduce IO latency, at the
648 cost of more retrieval system calls.
650 .BI iodepth_low \fR=\fPint
651 Low watermark indicating when to start filling the queue again. Default:
654 .BI direct \fR=\fPbool
655 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
657 .BI atomic \fR=\fPbool
658 If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
659 to be stable once acknowledged by the operating system. Only Linux supports
662 .BI buffered \fR=\fPbool
663 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
666 .BI offset \fR=\fPint
667 Offset in the file to start I/O. Data before the offset will not be touched.
669 .BI offset_increment \fR=\fPint
670 If this is provided, then the real offset becomes the
671 offset + offset_increment * thread_number, where the thread number is a
672 counter that starts at 0 and is incremented for each sub-job (i.e. when
673 numjobs option is specified). This option is useful if there are several jobs
674 which are intended to operate on a file in parallel disjoint segments, with
675 even spacing between the starting points.
677 .BI number_ios \fR=\fPint
678 Fio will normally perform IOs until it has exhausted the size of the region
679 set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
680 condition). With this setting, the range/size can be set independently of
681 the number of IOs to perform. When fio reaches this number, it will exit
682 normally and report status.
685 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
686 0, don't sync. Default: 0.
688 .BI fdatasync \fR=\fPint
689 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
690 data parts of the file. Default: 0.
692 .BI write_barrier \fR=\fPint
693 Make every Nth write a barrier write.
695 .BI sync_file_range \fR=\fPstr:int
696 Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
697 track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
698 \fRstr\fP can currently be one or more of:
702 SYNC_FILE_RANGE_WAIT_BEFORE
705 SYNC_FILE_RANGE_WRITE
708 SYNC_FILE_RANGE_WRITE
712 So if you do sync_file_range=wait_before,write:8, fio would use
713 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
714 Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
716 .BI overwrite \fR=\fPbool
717 If writing, setup the file first and do overwrites. Default: false.
719 .BI end_fsync \fR=\fPbool
720 Sync file contents when a write stage has completed. Default: false.
722 .BI fsync_on_close \fR=\fPbool
723 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
724 it will happen on every close, not just at the end of the job. Default: false.
726 .BI rwmixread \fR=\fPint
727 Percentage of a mixed workload that should be reads. Default: 50.
729 .BI rwmixwrite \fR=\fPint
730 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
731 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
732 overrides the first. This may interfere with a given rate setting, if fio is
733 asked to limit reads or writes to a certain rate. If that is the case, then
734 the distribution may be skewed. Default: 50.
736 .BI random_distribution \fR=\fPstr:float
737 By default, fio will use a completely uniform random distribution when asked
738 to perform random IO. Sometimes it is useful to skew the distribution in
739 specific ways, ensuring that some parts of the data is more hot than others.
740 Fio includes the following distribution models:
744 Uniform random distribution
754 When using a zipf or pareto distribution, an input value is also needed to
755 define the access pattern. For zipf, this is the zipf theta. For pareto,
756 it's the pareto power. Fio includes a test program, genzipf, that can be
757 used visualize what the given input values will yield in terms of hit rates.
758 If you wanted to use zipf with a theta of 1.2, you would use
759 random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
760 fio will disable use of the random map.
762 .BI percentage_random \fR=\fPint
763 For a random workload, set how big a percentage should be random. This defaults
764 to 100%, in which case the workload is fully random. It can be set from
765 anywhere from 0 to 100. Setting it to 0 would make the workload fully
766 sequential. It is possible to set different values for reads, writes, and
767 trim. To do so, simply use a comma separated list. See \fBblocksize\fR.
770 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
771 this parameter is given, a new offset will be chosen without looking at past
772 I/O history. This parameter is mutually exclusive with \fBverify\fR.
774 .BI softrandommap \fR=\fPbool
775 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
776 fails to allocate the map, if this option is set it will continue without a
777 random block map. As coverage will not be as complete as with random maps, this
778 option is disabled by default.
780 .BI random_generator \fR=\fPstr
781 Fio supports the following engines for generating IO offsets for random IO:
785 Strong 2^88 cycle random number generator
788 Linear feedback shift register generator
792 Tausworthe is a strong random number generator, but it requires tracking on the
793 side if we want to ensure that blocks are only read or written once. LFSR
794 guarantees that we never generate the same offset twice, and it's also less
795 computationally expensive. It's not a true random generator, however, though
796 for IO purposes it's typically good enough. LFSR only works with single block
797 sizes, not with workloads that use multiple block sizes. If used with such a
798 workload, fio may read or write some blocks multiple times.
801 Run job with given nice value. See \fBnice\fR\|(2).
804 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
807 .BI prioclass \fR=\fPint
808 Set I/O priority class. See \fBionice\fR\|(1).
810 .BI thinktime \fR=\fPint
811 Stall job for given number of microseconds between issuing I/Os.
813 .BI thinktime_spin \fR=\fPint
814 Pretend to spend CPU time for given number of microseconds, sleeping the rest
815 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
817 .BI thinktime_blocks \fR=\fPint
818 Only valid if thinktime is set - control how many blocks to issue, before
819 waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
820 make fio wait \fBthinktime\fR microseconds after every block. This
821 effectively makes any queue depth setting redundant, since no more than 1 IO
822 will be queued before we have to complete it and do our thinktime. In other
823 words, this setting effectively caps the queue depth if the latter is larger.
827 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
828 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
829 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
830 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
831 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
832 limit writes (to 500KB/sec), the latter will only limit reads.
834 .BI ratemin \fR=\fPint
835 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
836 Failing to meet this requirement will cause the job to exit. The same format
837 as \fBrate\fR is used for read vs write separation.
839 .BI rate_iops \fR=\fPint
840 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
841 specified independently of bandwidth. The same format as \fBrate\fR is used for
842 read vs write separation. If \fBblocksize\fR is a range, the smallest block
843 size is used as the metric.
845 .BI rate_iops_min \fR=\fPint
846 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
847 is used for read vs write separation.
849 .BI ratecycle \fR=\fPint
850 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
851 milliseconds. Default: 1000ms.
853 .BI latency_target \fR=\fPint
854 If set, fio will attempt to find the max performance point that the given
855 workload will run at while maintaining a latency below this target. The
856 values is given in microseconds. See \fBlatency_window\fR and
857 \fBlatency_percentile\fR.
859 .BI latency_window \fR=\fPint
860 Used with \fBlatency_target\fR to specify the sample window that the job
861 is run at varying queue depths to test the performance. The value is given
864 .BI latency_percentile \fR=\fPfloat
865 The percentage of IOs that must fall within the criteria specified by
866 \fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
867 to 100.0, meaning that all IOs must be equal or below to the value set
868 by \fBlatency_target\fR.
870 .BI max_latency \fR=\fPint
871 If set, fio will exit the job if it exceeds this maximum latency. It will exit
874 .BI cpumask \fR=\fPint
875 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
876 may run on. See \fBsched_setaffinity\fR\|(2).
878 .BI cpus_allowed \fR=\fPstr
879 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
881 .BI cpus_allowed_policy \fR=\fPstr
882 Set the policy of how fio distributes the CPUs specified by \fBcpus_allowed\fR
883 or \fBcpumask\fR. Two policies are supported:
888 All jobs will share the CPU set specified.
891 Each job will get a unique CPU from the CPU set.
894 \fBshared\fR is the default behaviour, if the option isn't specified. If
895 \fBsplit\fR is specified, then fio will assign one cpu per job. If not enough
896 CPUs are given for the jobs listed, then fio will roundrobin the CPUs in
901 .BI numa_cpu_nodes \fR=\fPstr
902 Set this job running on specified NUMA nodes' CPUs. The arguments allow
903 comma delimited list of cpu numbers, A-B ranges, or 'all'.
905 .BI numa_mem_policy \fR=\fPstr
906 Set this job's memory policy and corresponding NUMA nodes. Format of
910 .B <mode>[:<nodelist>]
913 is one of the following memory policy:
915 .B default, prefer, bind, interleave, local
918 For \fBdefault\fR and \fBlocal\fR memory policy, no \fBnodelist\fR is
919 needed to be specified. For \fBprefer\fR, only one node is
920 allowed. For \fBbind\fR and \fBinterleave\fR, \fBnodelist\fR allows
921 comma delimited list of numbers, A-B ranges, or 'all'.
923 .BI startdelay \fR=\fPirange
924 Delay start of job for the specified number of seconds. Supports all time
925 suffixes to allow specification of hours, minutes, seconds and
926 milliseconds - seconds are the default if a unit is ommited.
927 Can be given as a range which causes each thread to choose randomly out of the
930 .BI runtime \fR=\fPint
931 Terminate processing after the specified number of seconds.
934 If given, run for the specified \fBruntime\fR duration even if the files are
935 completely read or written. The same workload will be repeated as many times
936 as \fBruntime\fR allows.
938 .BI ramp_time \fR=\fPint
939 If set, fio will run the specified workload for this amount of time before
940 logging any performance numbers. Useful for letting performance settle before
941 logging results, thus minimizing the runtime required for stable results. Note
942 that the \fBramp_time\fR is considered lead in time for a job, thus it will
943 increase the total runtime if a special timeout or runtime is specified.
945 .BI invalidate \fR=\fPbool
946 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
949 Use synchronous I/O for buffered writes. For the majority of I/O engines,
950 this means using O_SYNC. Default: false.
952 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
953 Allocation method for I/O unit buffer. Allowed values are:
958 Allocate memory with \fBmalloc\fR\|(3).
961 Use shared memory buffers allocated through \fBshmget\fR\|(2).
964 Same as \fBshm\fR, but use huge pages as backing.
967 Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
968 is given after the option in the format `:\fIfile\fR'.
971 Same as \fBmmap\fR, but use huge files as backing.
974 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
975 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
976 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
977 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
978 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
979 and the documentation for that. Normally you just need to echo an appropriate
980 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
984 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
985 This indicates the memory alignment of the IO memory buffers. Note that the
986 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
987 the alignment of the following buffers are given by the \fBbs\fR used. In
988 other words, if using a \fBbs\fR that is a multiple of the page sized in the
989 system, all buffers will be aligned to this value. If using a \fBbs\fR that
990 is not page aligned, the alignment of subsequent IO memory buffers is the
991 sum of the \fBiomem_align\fR and \fBbs\fR used.
993 .BI hugepage\-size \fR=\fPint
994 Defines the size of a huge page. Must be at least equal to the system setting.
995 Should be a multiple of 1MB. Default: 4MB.
998 Terminate all jobs when one finishes. Default: wait for each job to finish.
1000 .BI bwavgtime \fR=\fPint
1001 Average bandwidth calculations over the given time in milliseconds. Default:
1004 .BI iopsavgtime \fR=\fPint
1005 Average IOPS calculations over the given time in milliseconds. Default:
1008 .BI create_serialize \fR=\fPbool
1009 If true, serialize file creation for the jobs. Default: true.
1011 .BI create_fsync \fR=\fPbool
1012 \fBfsync\fR\|(2) data file after creation. Default: true.
1014 .BI create_on_open \fR=\fPbool
1015 If true, the files are not created until they are opened for IO by the job.
1017 .BI create_only \fR=\fPbool
1018 If true, fio will only run the setup phase of the job. If files need to be
1019 laid out or updated on disk, only that will be done. The actual job contents
1022 .BI pre_read \fR=\fPbool
1023 If this is given, files will be pre-read into memory before starting the given
1024 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
1025 pointless to pre-read and then drop the cache. This will only work for IO
1026 engines that are seekable, since they allow you to read the same data
1027 multiple times. Thus it will not work on eg network or splice IO.
1029 .BI unlink \fR=\fPbool
1030 Unlink job files when done. Default: false.
1032 .BI loops \fR=\fPint
1033 Specifies the number of iterations (runs of the same workload) of this job.
1036 .BI verify_only \fR=\fPbool
1037 Do not perform the specified workload, only verify data still matches previous
1038 invocation of this workload. This option allows one to check data multiple
1039 times at a later date without overwriting it. This option makes sense only for
1040 workloads that write data, and does not support workloads with the
1041 \fBtime_based\fR option set.
1043 .BI do_verify \fR=\fPbool
1044 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
1047 .BI verify \fR=\fPstr
1048 Method of verifying file contents after each iteration of the job. Allowed
1053 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1 xxhash
1054 Store appropriate checksum in the header of each block. crc32c-intel is
1055 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
1056 not supported by the system.
1059 Write extra information about each I/O (timestamp, block number, etc.). The
1060 block number is verified. See \fBverify_pattern\fR as well.
1063 Pretend to verify. Used for testing internals.
1066 This option can be used for repeated burn-in tests of a system to make sure
1067 that the written data is also correctly read back. If the data direction given
1068 is a read or random read, fio will assume that it should verify a previously
1069 written file. If the data direction includes any form of write, the verify will
1070 be of the newly written data.
1073 .BI verifysort \fR=\fPbool
1074 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
1075 read them back in a sorted manner. Default: true.
1077 .BI verifysort_nr \fR=\fPint
1078 Pre-load and sort verify blocks for a read workload.
1080 .BI verify_offset \fR=\fPint
1081 Swap the verification header with data somewhere else in the block before
1082 writing. It is swapped back before verifying.
1084 .BI verify_interval \fR=\fPint
1085 Write the verification header for this number of bytes, which should divide
1086 \fBblocksize\fR. Default: \fBblocksize\fR.
1088 .BI verify_pattern \fR=\fPstr
1089 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
1090 with totally random bytes, but sometimes it's interesting to fill with a known
1091 pattern for io verification purposes. Depending on the width of the pattern,
1092 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
1093 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
1094 has to be a hex number that starts with either "0x" or "0X". Use with
1097 .BI verify_fatal \fR=\fPbool
1098 If true, exit the job on the first observed verification failure. Default:
1101 .BI verify_dump \fR=\fPbool
1102 If set, dump the contents of both the original data block and the data block we
1103 read off disk to files. This allows later analysis to inspect just what kind of
1104 data corruption occurred. Off by default.
1106 .BI verify_async \fR=\fPint
1107 Fio will normally verify IO inline from the submitting thread. This option
1108 takes an integer describing how many async offload threads to create for IO
1109 verification instead, causing fio to offload the duty of verifying IO contents
1110 to one or more separate threads. If using this offload option, even sync IO
1111 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
1112 allows them to have IO in flight while verifies are running.
1114 .BI verify_async_cpus \fR=\fPstr
1115 Tell fio to set the given CPU affinity on the async IO verification threads.
1116 See \fBcpus_allowed\fP for the format used.
1118 .BI verify_backlog \fR=\fPint
1119 Fio will normally verify the written contents of a job that utilizes verify
1120 once that job has completed. In other words, everything is written then
1121 everything is read back and verified. You may want to verify continually
1122 instead for a variety of reasons. Fio stores the meta data associated with an
1123 IO block in memory, so for large verify workloads, quite a bit of memory would
1124 be used up holding this meta data. If this option is enabled, fio will write
1125 only N blocks before verifying these blocks.
1127 .BI verify_backlog_batch \fR=\fPint
1128 Control how many blocks fio will verify if verify_backlog is set. If not set,
1129 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
1130 read back and verified). If \fBverify_backlog_batch\fR is less than
1131 \fBverify_backlog\fR then not all blocks will be verified, if
1132 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
1133 will be verified more than once.
1135 .BI trim_percentage \fR=\fPint
1136 Number of verify blocks to discard/trim.
1138 .BI trim_verify_zero \fR=\fPbool
1139 Verify that trim/discarded blocks are returned as zeroes.
1141 .BI trim_backlog \fR=\fPint
1142 Trim after this number of blocks are written.
1144 .BI trim_backlog_batch \fR=\fPint
1145 Trim this number of IO blocks.
1147 .BI experimental_verify \fR=\fPbool
1148 Enable experimental verification.
1150 .B stonewall "\fR,\fP wait_for_previous"
1151 Wait for preceding jobs in the job file to exit before starting this one.
1152 \fBstonewall\fR implies \fBnew_group\fR.
1155 Start a new reporting group. If not given, all jobs in a file will be part
1156 of the same reporting group, unless separated by a stonewall.
1158 .BI numjobs \fR=\fPint
1159 Number of clones (processes/threads performing the same workload) of this job.
1163 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
1167 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
1168 with \fBfork\fR\|(2).
1170 .BI zonesize \fR=\fPint
1171 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
1173 .BI zonerange \fR=\fPint
1174 Give size of an IO zone. See \fBzoneskip\fR.
1176 .BI zoneskip \fR=\fPint
1177 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
1180 .BI write_iolog \fR=\fPstr
1181 Write the issued I/O patterns to the specified file. Specify a separate file
1182 for each job, otherwise the iologs will be interspersed and the file may be
1185 .BI read_iolog \fR=\fPstr
1186 Replay the I/O patterns contained in the specified file generated by
1187 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
1189 .BI replay_no_stall \fR=\fPint
1190 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1191 attempts to respect timing information between I/Os. Enabling
1192 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
1193 still respecting ordering.
1195 .BI replay_redirect \fR=\fPstr
1196 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1197 is to replay the IOPS onto the major/minor device that each IOP was recorded
1198 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
1199 single specified device regardless of the device it was recorded from.
1201 .BI write_bw_log \fR=\fPstr
1202 If given, write a bandwidth log of the jobs in this job file. Can be used to
1203 store data of the bandwidth of the jobs in their lifetime. The included
1204 fio_generate_plots script uses gnuplot to turn these text files into nice
1205 graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
1206 option, the postfix is _bw.x.log, where x is the index of the job (1..N,
1207 where N is the number of jobs)
1209 .BI write_lat_log \fR=\fPstr
1210 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
1211 filename is given with this option, the default filename of
1212 "jobname_type.x.log" is used, where x is the index of the job (1..N, where
1213 N is the number of jobs). Even if the filename is given, fio will still
1214 append the type of log.
1216 .BI write_iops_log \fR=\fPstr
1217 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
1218 option, the default filename of "jobname_type.x.log" is used, where x is the
1219 index of the job (1..N, where N is the number of jobs). Even if the filename
1220 is given, fio will still append the type of log.
1222 .BI log_avg_msec \fR=\fPint
1223 By default, fio will log an entry in the iops, latency, or bw log for every
1224 IO that completes. When writing to the disk log, that can quickly grow to a
1225 very large size. Setting this option makes fio average the each log entry
1226 over the specified period of time, reducing the resolution of the log.
1229 .BI log_offset \fR=\fPbool
1230 If this is set, the iolog options will include the byte offset for the IO
1231 entry as well as the other data values.
1233 .BI log_compression \fR=\fPint
1234 If this is set, fio will compress the IO logs as it goes, to keep the memory
1235 footprint lower. When a log reaches the specified size, that chunk is removed
1236 and compressed in the background. Given that IO logs are fairly highly
1237 compressible, this yields a nice memory savings for longer runs. The downside
1238 is that the compression will consume some background CPU cycles, so it may
1239 impact the run. This, however, is also true if the logging ends up consuming
1240 most of the system memory. So pick your poison. The IO logs are saved
1241 normally at the end of a run, by decompressing the chunks and storing them
1242 in the specified log file. This feature depends on the availability of zlib.
1244 .BI log_store_compressed \fR=\fPbool
1245 If set, and \fBlog\fR_compression is also set, fio will store the log files in
1246 a compressed format. They can be decompressed with fio, using the
1247 \fB\-\-inflate-log\fR command line parameter. The files will be stored with a
1250 .BI disable_lat \fR=\fPbool
1251 Disable measurements of total latency numbers. Useful only for cutting
1252 back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
1253 really high IOPS rates. Note that to really get rid of a large amount of these
1254 calls, this option must be used with disable_slat and disable_bw as well.
1256 .BI disable_clat \fR=\fPbool
1257 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
1259 .BI disable_slat \fR=\fPbool
1260 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
1262 .BI disable_bw_measurement \fR=\fPbool
1263 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
1265 .BI lockmem \fR=\fPint
1266 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
1267 simulate a smaller amount of memory. The amount specified is per worker.
1269 .BI exec_prerun \fR=\fPstr
1270 Before running the job, execute the specified command with \fBsystem\fR\|(3).
1272 Output is redirected in a file called \fBjobname.prerun.txt\fR
1275 .BI exec_postrun \fR=\fPstr
1276 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
1278 Output is redirected in a file called \fBjobname.postrun.txt\fR
1281 .BI ioscheduler \fR=\fPstr
1282 Attempt to switch the device hosting the file to the specified I/O scheduler.
1284 .BI disk_util \fR=\fPbool
1285 Generate disk utilization statistics if the platform supports it. Default: true.
1287 .BI clocksource \fR=\fPstr
1288 Use the given clocksource as the base of timing. The supported options are:
1292 \fBgettimeofday\fR\|(2)
1295 \fBclock_gettime\fR\|(2)
1298 Internal CPU clock source
1302 \fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
1303 (and fio is heavy on time calls). Fio will automatically use this clocksource
1304 if it's supported and considered reliable on the system it is running on,
1305 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
1306 means supporting TSC Invariant.
1308 .BI gtod_reduce \fR=\fPbool
1309 Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
1310 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
1311 \fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
1312 the gtod() calls we would have done if all time keeping was enabled.
1314 .BI gtod_cpu \fR=\fPint
1315 Sometimes it's cheaper to dedicate a single thread of execution to just getting
1316 the current time. Fio (and databases, for instance) are very intensive on
1317 \fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
1318 nothing but logging current time to a shared memory location. Then the other
1319 threads/processes that run IO workloads need only copy that segment, instead of
1320 entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
1321 these time calls will be excluded from other uses. Fio will manually clear it
1322 from the CPU mask of other jobs.
1324 .BI ignore_error \fR=\fPstr
1325 Sometimes you want to ignore some errors during test in that case you can specify
1326 error list for each error type.
1328 ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
1330 errors for given error type is separated with ':'.
1331 Error may be symbol ('ENOSPC', 'ENOMEM') or an integer.
1333 Example: ignore_error=EAGAIN,ENOSPC:122 .
1335 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from WRITE.
1337 .BI error_dump \fR=\fPbool
1338 If set dump every error even if it is non fatal, true by default. If disabled
1339 only fatal error will be dumped
1341 .BI profile \fR=\fPstr
1342 Select a specific builtin performance test.
1344 .BI cgroup \fR=\fPstr
1345 Add job to this control group. If it doesn't exist, it will be created.
1346 The system must have a mounted cgroup blkio mount point for this to work. If
1347 your system doesn't have it mounted, you can do so with:
1349 # mount \-t cgroup \-o blkio none /cgroup
1351 .BI cgroup_weight \fR=\fPint
1352 Set the weight of the cgroup to this value. See the documentation that comes
1353 with the kernel, allowed values are in the range of 100..1000.
1355 .BI cgroup_nodelete \fR=\fPbool
1356 Normally fio will delete the cgroups it has created after the job completion.
1357 To override this behavior and to leave cgroups around after the job completion,
1358 set cgroup_nodelete=1. This can be useful if one wants to inspect various
1359 cgroup files after job completion. Default: false
1362 Instead of running as the invoking user, set the user ID to this value before
1363 the thread/process does any work.
1366 Set group ID, see \fBuid\fR.
1368 .BI unit_base \fR=\fPint
1369 Base unit for reporting. Allowed values are:
1373 Use auto-detection (default).
1383 .BI flow_id \fR=\fPint
1384 The ID of the flow. If not specified, it defaults to being a global flow. See
1388 Weight in token-based flow control. If this value is used, then there is a
1389 \fBflow counter\fR which is used to regulate the proportion of activity between
1390 two or more jobs. fio attempts to keep this flow counter near zero. The
1391 \fBflow\fR parameter stands for how much should be added or subtracted to the
1392 flow counter on each iteration of the main I/O loop. That is, if one job has
1393 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
1394 1:8 ratio in how much one runs vs the other.
1396 .BI flow_watermark \fR=\fPint
1397 The maximum value that the absolute value of the flow counter is allowed to
1398 reach before the job must wait for a lower value of the counter.
1400 .BI flow_sleep \fR=\fPint
1401 The period of time, in microseconds, to wait after the flow watermark has been
1402 exceeded before retrying operations
1404 .BI clat_percentiles \fR=\fPbool
1405 Enable the reporting of percentiles of completion latencies.
1407 .BI percentile_list \fR=\fPfloat_list
1408 Overwrite the default list of percentiles for completion
1409 latencies. Each number is a floating number in the range (0,100], and
1410 the maximum length of the list is 20. Use ':' to separate the
1411 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1412 report the values of completion latency below which 99.5% and 99.9% of
1413 the observed latencies fell, respectively.
1414 .SS "Ioengine Parameters List"
1415 Some parameters are only valid when a specific ioengine is in use. These are
1416 used identically to normal parameters, with the caveat that when used on the
1417 command line, they must come after the ioengine.
1419 .BI (cpu)cpuload \fR=\fPint
1420 Attempt to use the specified percentage of CPU cycles.
1422 .BI (cpu)cpuchunks \fR=\fPint
1423 Split the load into cycles of the given time. In microseconds.
1425 .BI (cpu)exit_on_io_done \fR=\fPbool
1426 Detect when IO threads are done, then exit.
1428 .BI (libaio)userspace_reap
1429 Normally, with the libaio engine in use, fio will use
1430 the io_getevents system call to reap newly returned events.
1431 With this flag turned on, the AIO ring will be read directly
1432 from user-space to reap events. The reaping mode is only
1433 enabled when polling for a minimum of 0 events (eg when
1434 iodepth_batch_complete=0).
1436 .BI (net,netsplice)hostname \fR=\fPstr
1437 The host name or IP address to use for TCP or UDP based IO.
1438 If the job is a TCP listener or UDP reader, the hostname is not
1439 used and must be omitted unless it is a valid UDP multicast address.
1441 .BI (net,netsplice)port \fR=\fPint
1442 The TCP or UDP port to bind to or connect to.
1444 .BI (net,netsplice)interface \fR=\fPstr
1445 The IP address of the network interface used to send or receive UDP multicast
1448 .BI (net,netsplice)ttl \fR=\fPint
1449 Time-to-live value for outgoing UDP multicast packets. Default: 1
1451 .BI (net,netsplice)nodelay \fR=\fPbool
1452 Set TCP_NODELAY on TCP connections.
1454 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1455 The network protocol to use. Accepted values are:
1460 Transmission control protocol
1463 Transmission control protocol V6
1466 User datagram protocol
1469 User datagram protocol V6
1475 When the protocol is TCP or UDP, the port must also be given,
1476 as well as the hostname if the job is a TCP listener or UDP
1477 reader. For unix sockets, the normal filename option should be
1478 used and the port is invalid.
1481 .BI (net,netsplice)listen
1482 For TCP network connections, tell fio to listen for incoming
1483 connections rather than initiating an outgoing connection. The
1484 hostname must be omitted if this option is used.
1486 .BI (net, pingpong) \fR=\fPbool
1487 Normally a network writer will just continue writing data, and a network reader
1488 will just consume packets. If pingpong=1 is set, a writer will send its normal
1489 payload to the reader, then wait for the reader to send the same payload back.
1490 This allows fio to measure network latencies. The submission and completion
1491 latencies then measure local time spent sending or receiving, and the
1492 completion latency measures how long it took for the other end to receive and
1493 send back. For UDP multicast traffic pingpong=1 should only be set for a single
1494 reader when multiple readers are listening to the same address.
1496 .BI (e4defrag,donorname) \fR=\fPstr
1497 File will be used as a block donor (swap extents between files)
1499 .BI (e4defrag,inplace) \fR=\fPint
1500 Configure donor file block allocation strategy
1503 Preallocate donor's file on init
1506 allocate space immediately inside defragment event, and free right after event
1509 .BI (rbd)rbdname \fR=\fPstr
1510 Specifies the name of the RBD.
1512 .BI (rbd)pool \fR=\fPstr
1513 Specifies the name of the Ceph pool containing the RBD.
1515 .BI (rbd)clientname \fR=\fPstr
1516 Specifies the username (without the 'client.' prefix) used to access the Ceph cluster.
1518 While running, \fBfio\fR will display the status of the created jobs. For
1522 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1525 The characters in the first set of brackets denote the current status of each
1526 threads. The possible values are:
1532 Setup but not started.
1538 Initialized, waiting.
1541 Running, doing sequential reads.
1544 Running, doing random reads.
1547 Running, doing sequential writes.
1550 Running, doing random writes.
1553 Running, doing mixed sequential reads/writes.
1556 Running, doing mixed random reads/writes.
1559 Running, currently waiting for \fBfsync\fR\|(2).
1562 Running, verifying written data.
1565 Exited, not reaped by main thread.
1568 Exited, thread reaped.
1572 The second set of brackets shows the estimated completion percentage of
1573 the current group. The third set shows the read and write I/O rate,
1574 respectively. Finally, the estimated run time of the job is displayed.
1576 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1577 for each thread, each group of threads, and each disk, in that order.
1579 Per-thread statistics first show the threads client number, group-id, and
1580 error code. The remaining figures are as follows:
1584 Number of megabytes of I/O performed.
1587 Average data rate (bandwidth).
1593 Submission latency minimum, maximum, average and standard deviation. This is
1594 the time it took to submit the I/O.
1597 Completion latency minimum, maximum, average and standard deviation. This
1598 is the time between submission and completion.
1601 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1602 and standard deviation.
1605 CPU usage statistics. Includes user and system time, number of context switches
1606 this thread went through and number of major and minor page faults.
1609 Distribution of I/O depths. Each depth includes everything less than (or equal)
1610 to it, but greater than the previous depth.
1613 Number of read/write requests issued, and number of short read/write requests.
1616 Distribution of I/O completion latencies. The numbers follow the same pattern
1620 The group statistics show:
1625 Number of megabytes I/O performed.
1628 Aggregate bandwidth of threads in the group.
1631 Minimum average bandwidth a thread saw.
1634 Maximum average bandwidth a thread saw.
1637 Shortest runtime of threads in the group.
1640 Longest runtime of threads in the group.
1644 Finally, disk statistics are printed with reads first:
1649 Number of I/Os performed by all groups.
1652 Number of merges in the I/O scheduler.
1655 Number of ticks we kept the disk busy.
1658 Total time spent in the disk queue.
1665 It is also possible to get fio to dump the current output while it is
1666 running, without terminating the job. To do that, send fio the \fBUSR1\fR
1669 If the \fB\-\-minimal\fR / \fB\-\-append-terse\fR options are given, the
1670 results will be printed/appended in a semicolon-delimited format suitable for
1672 A job description (if provided) follows on a new line. Note that the first
1673 number in the line is the version number. If the output has to be changed
1674 for some reason, this number will be incremented by 1 to signify that
1675 change. The fields are:
1678 .B terse version, fio version, jobname, groupid, error
1682 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1686 .B min, max, mean, standard deviation
1690 .B min, max, mean, standard deviation
1692 Completion latency percentiles (20 fields):
1694 .B Xth percentile=usec
1698 .B min, max, mean, standard deviation
1702 .B min, max, aggregate percentage of total, mean, standard deviation
1708 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1712 .B min, max, mean, standard deviation
1716 .B min, max, mean, standard deviation
1718 Completion latency percentiles (20 fields):
1720 .B Xth percentile=usec
1724 .B min, max, mean, standard deviation
1728 .B min, max, aggregate percentage of total, mean, standard deviation
1734 .B user, system, context switches, major page faults, minor page faults
1737 IO depth distribution:
1739 .B <=1, 2, 4, 8, 16, 32, >=64
1742 IO latency distribution:
1746 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1750 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1754 Disk utilization (1 for each disk used):
1756 .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
1759 Error Info (dependent on continue_on_error, default off):
1761 .B total # errors, first error code
1764 .B text description (if provided in config - appears on newline)
1767 Normally you would run fio as a stand-alone application on the machine
1768 where the IO workload should be generated. However, it is also possible to
1769 run the frontend and backend of fio separately. This makes it possible to
1770 have a fio server running on the machine(s) where the IO workload should
1771 be running, while controlling it from another machine.
1773 To start the server, you would do:
1775 \fBfio \-\-server=args\fR
1777 on that machine, where args defines what fio listens to. The arguments
1778 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1779 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain
1780 socket. 'hostname' is either a hostname or IP address, and 'port' is the port to
1781 listen to (only valid for TCP/IP, not a local socket). Some examples:
1785 Start a fio server, listening on all interfaces on the default port (8765).
1787 2) fio \-\-server=ip:hostname,4444
1789 Start a fio server, listening on IP belonging to hostname and on port 4444.
1791 3) fio \-\-server=ip6:::1,4444
1793 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1795 4) fio \-\-server=,4444
1797 Start a fio server, listening on all interfaces on port 4444.
1799 5) fio \-\-server=1.2.3.4
1801 Start a fio server, listening on IP 1.2.3.4 on the default port.
1803 6) fio \-\-server=sock:/tmp/fio.sock
1805 Start a fio server, listening on the local socket /tmp/fio.sock.
1807 When a server is running, you can connect to it from a client. The client
1810 fio \-\-local-args \-\-client=server \-\-remote-args <job file(s)>
1812 where \-\-local-args are arguments that are local to the client where it is
1813 running, 'server' is the connect string, and \-\-remote-args and <job file(s)>
1814 are sent to the server. The 'server' string follows the same format as it
1815 does on the server side, to allow IP/hostname/socket and port strings.
1816 You can connect to multiple clients as well, to do that you could run:
1818 fio \-\-client=server2 \-\-client=server2 <job file(s)>
1822 was written by Jens Axboe <jens.axboe@oracle.com>,
1823 now Jens Axboe <jaxboe@fusionio.com>.
1825 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1826 on documentation by Jens Axboe.
1827 .SH "REPORTING BUGS"
1828 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1831 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1833 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob