1 .TH fio 1 "September 2007" "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 \-\-output \fR=\fPfilename
16 Write output to \fIfilename\fR.
18 .BI \-\-timeout \fR=\fPtimeout
19 Limit run time to \fItimeout\fR seconds.
22 Generate per-job latency logs.
25 Generate per-job bandwidth logs.
28 Print statistics in a terse, semicolon-delimited format.
30 .BI \-\-showcmd \fR=\fPjobfile
31 Convert \fIjobfile\fR to a set of command-line options.
34 Enable read-only safety checks.
36 .BI \-\-eta \fR=\fPwhen
37 Specifies when real-time ETA estimate should be printed. \fIwhen\fR may
38 be one of `always', `never' or `auto'.
40 .BI \-\-section \fR=\fPsec
41 Only run section \fIsec\fR from job file.
43 .BI \-\-cmdhelp \fR=\fPcommand
44 Print help information for \fIcommand\fR. May be `all' for all commands.
46 .BI \-\-debug \fR=\fPtype
47 Enable verbose tracing of various fio actions. May be `all' for all types
48 or individual types separated by a comma (eg \-\-debug=io,file). `help' will
49 list all available tracing options.
52 Display usage information and exit.
55 Display version information and exit.
57 .B \-\-terse\-version\fR=\fPtype
58 Terse version output format
60 Job files are in `ini' format. They consist of one or more
61 job definitions, which begin with a job name in square brackets and
62 extend to the next job name. The job name can be any ASCII string
63 except `global', which has a special meaning. Following the job name is
64 a sequence of zero or more parameters, one per line, that define the
65 behavior of the job. Any line starting with a `;' or `#' character is
66 considered a comment and ignored.
68 If \fIjobfile\fR is specified as `-', the job file will be read from
71 The global section contains default parameters for jobs specified in the
72 job file. A job is only affected by global sections residing above it,
73 and there may be any number of global sections. Specific job definitions
74 may override any parameter set in global sections.
77 Some parameters may take arguments of a specific type. The types used are:
80 String: a sequence of alphanumeric characters.
83 SI integer: a whole number, possibly containing a suffix denoting the base unit
84 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
85 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
86 respectively. The suffix is not case sensitive. If prefixed with '0x', the
87 value is assumed to be base 16 (hexadecimal). A suffix may include a trailing 'b',
88 for instance 'kb' is identical to 'k'. You can specify a base 10 value
89 by using 'KiB', 'MiB', 'GiB', etc. This is useful for disk drives where
90 values are often given in base 10 values. Specifying '30GiB' will get you
94 Boolean: a true or false value. `0' denotes false, `1' denotes true.
97 Integer range: a range of integers specified in the format
98 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
99 \fIupper\fR may contain a suffix as described above. If an option allows two
100 sets of ranges, they are separated with a `,' or `/' character. For example:
104 List of floating numbers: A list of floating numbers, separated by
109 May be used to override the job name. On the command line, this parameter
110 has the special purpose of signalling the start of a new job.
112 .BI description \fR=\fPstr
113 Human-readable description of the job. It is printed when the job is run, but
114 otherwise has no special purpose.
116 .BI directory \fR=\fPstr
117 Prefix filenames with this directory. Used to place files in a location other
120 .BI filename \fR=\fPstr
122 normally makes up a file name based on the job name, thread number, and file
123 number. If you want to share files between threads in a job or several jobs,
124 specify a \fIfilename\fR for each of them to override the default. If the I/O
125 engine used is `net', \fIfilename\fR is the host and port to connect to in the
126 format \fIhost\fR/\fIport\fR. If the I/O engine is file-based, you can specify
127 a number of files by separating the names with a `:' character. `\-' is a
128 reserved name, meaning stdin or stdout, depending on the read/write direction
131 .BI lockfile \fR=\fPstr
132 Fio defaults to not locking any files before it does IO to them. If a file or
133 file descriptor is shared, fio can serialize IO to that file to make the end
134 result consistent. This is usual for emulating real workloads that share files.
140 No locking. This is the default.
143 Only one thread or process may do IO at the time, excluding all others.
146 Read-write locking on the file. Many readers may access the file at the same
147 time, but writes get exclusive access.
150 The option may be post-fixed with a lock batch number. If set, then each
151 thread/process may do that amount of IOs to the file before giving up the lock.
152 Since lock acquisition is expensive, batching the lock/unlocks will speed up IO.
155 .BI opendir \fR=\fPstr
156 Recursively open any files below directory \fIstr\fR.
158 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
159 Type of I/O pattern. Accepted values are:
176 Mixed sequential reads and writes.
179 Mixed random reads and writes.
182 For mixed I/O, the default split is 50/50. For certain types of io the result
183 may still be skewed a bit, since the speed may be different. It is possible to
184 specify a number of IO's to do before getting a new offset, this is one by
185 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
186 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
187 value of 8. If the postfix is used with a sequential IO pattern, then the value
188 specified will be added to the generated offset for each IO. For instance,
189 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
190 into sequential IO with holes. See the \fBrw_sequencer\fR option.
193 .BI rw_sequencer \fR=\fPstr
194 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
195 then this option controls how that number modifies the IO offset being
196 generated. Accepted values are:
201 Generate sequential offset
204 Generate the same offset
207 \fBsequential\fR is only useful for random IO, where fio would normally
208 generate a new random offset for every IO. If you append eg 8 to randread, you
209 would get a new random offset for every 8 IO's. The result would be a seek for
210 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
211 that. As sequential IO is already sequential, setting \fBsequential\fR for that
212 would not result in any differences. \fBidentical\fR behaves in a similar
213 fashion, except it sends the same offset 8 number of times before generating a
218 .BI kb_base \fR=\fPint
219 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
220 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
221 reasons. Allow values are 1024 or 1000, with 1024 being the default.
223 .BI randrepeat \fR=\fPbool
224 Seed the random number generator in a predictable way so results are repeatable
225 across runs. Default: true.
227 .BI use_os_rand \fR=\fPbool
228 Fio can either use the random generator supplied by the OS to generator random
229 offsets, or it can use it's own internal generator (based on Tausworthe).
230 Default is to use the internal generator, which is often of better quality and
231 faster. Default: false.
233 .BI fallocate \fR=\fPstr
234 Whether pre-allocation is performed when laying down files. Accepted values
240 Do not pre-allocate space.
243 Pre-allocate via posix_fallocate().
246 Pre-allocate via fallocate() with FALLOC_FL_KEEP_SIZE set.
249 Backward-compatible alias for 'none'.
252 Backward-compatible alias for 'posix'.
255 May not be available on all supported platforms. 'keep' is only
256 available on Linux. If using ZFS on Solaris this must be set to 'none'
257 because ZFS doesn't support it. Default: 'posix'.
260 .BI fadvise_hint \fR=\fPbool
261 Disable use of \fIposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
262 are likely to be issued. Default: true.
265 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
266 been transfered, unless limited by other options (\fBruntime\fR, for instance).
267 Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
268 divided between the available files for the job. If not set, fio will use the
269 full size of the given files or devices. If the the files do not exist, size
270 must be given. It is also possible to give size as a percentage between 1 and
271 100. If size=20% is given, fio will use 20% of the full size of the given files
274 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
275 Sets size to something really large and waits for ENOSPC (no space left on
276 device) as the terminating condition. Only makes sense with sequential write.
277 For a read workload, the mount point will be filled first then IO started on
278 the result. This option doesn't make sense if operating on a raw device node,
279 since the size of that is already known by the file system. Additionally,
280 writing beyond end-of-device will not return ENOSPC there.
282 .BI filesize \fR=\fPirange
283 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
284 for files at random within the given range, limited to \fBsize\fR in total (if
285 that is given). If \fBfilesize\fR is not specified, each created file is the
288 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
289 Block size for I/O units. Default: 4k. Values for reads and writes can be
290 specified separately in the format \fIread\fR,\fIwrite\fR, either of
291 which may be empty to leave that value at its default.
293 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
294 Specify a range of I/O block sizes. The issued I/O unit will always be a
295 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
296 to both reads and writes if only one range is given, but can be specified
297 separately with a comma seperating the values. Example: bsrange=1k-4k,2k-8k.
298 Also (see \fBblocksize\fR).
300 .BI bssplit \fR=\fPstr
301 This option allows even finer grained control of the block sizes issued,
302 not just even splits between them. With this option, you can weight various
303 block sizes for exact control of the issued IO for a job that has mixed
304 block sizes. The format of the option is bssplit=blocksize/percentage,
305 optionally adding as many definitions as needed separated by a colon.
306 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
307 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
308 splits to reads and writes. The format is identical to what the
309 \fBbs\fR option accepts, the read and write parts are separated with a
312 .B blocksize_unaligned\fR,\fP bs_unaligned
313 If set, any size in \fBblocksize_range\fR may be used. This typically won't
314 work with direct I/O, as that normally requires sector alignment.
316 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
317 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
318 the minimum blocksize given. Minimum alignment is typically 512b
319 for using direct IO, though it usually depends on the hardware block size.
320 This option is mutually exclusive with using a random map for files, so it
321 will turn off that option.
324 Initialise buffers with all zeros. Default: fill buffers with random data.
327 If this option is given, fio will refill the IO buffers on every submit. The
328 default is to only fill it at init time and reuse that data. Only makes sense
329 if zero_buffers isn't specified, naturally. If data verification is enabled,
330 refill_buffers is also automatically enabled.
332 .BI scramble_buffers \fR=\fPbool
333 If \fBrefill_buffers\fR is too costly and the target is using data
334 deduplication, then setting this option will slightly modify the IO buffer
335 contents to defeat normal de-dupe attempts. This is not enough to defeat
336 more clever block compression attempts, but it will stop naive dedupe
337 of blocks. Default: true.
339 .BI nrfiles \fR=\fPint
340 Number of files to use for this job. Default: 1.
342 .BI openfiles \fR=\fPint
343 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
345 .BI file_service_type \fR=\fPstr
346 Defines how files to service are selected. The following types are defined:
351 Choose a file at random
354 Round robin over open files (default).
356 Do each file in the set sequentially.
359 The number of I/Os to issue before switching a new file can be specified by
360 appending `:\fIint\fR' to the service type.
363 .BI ioengine \fR=\fPstr
364 Defines how the job issues I/O. The following types are defined:
369 Basic \fIread\fR\|(2) or \fIwrite\fR\|(2) I/O. \fIfseek\fR\|(2) is used to
370 position the I/O location.
373 Basic \fIpread\fR\|(2) or \fIpwrite\fR\|(2) I/O.
376 Basic \fIreadv\fR\|(2) or \fIwritev\fR\|(2) I/O. Will emulate queuing by
377 coalescing adjacents IOs into a single submission.
380 Linux native asynchronous I/O. This engine also has a sub-option,
381 \fBuserspace_reap\fR. To set it, use \fBioengine=libaio:userspace_reap\fR.
382 Normally, with the libaio engine in use, fio will use the
383 \fIio_getevents\fR\|(3) system call to reap newly returned events. With this
384 flag turned on, the AIO ring will be read directly from user-space to reap
385 events. The reaping mode is only enabled when polling for a minimum of \fB0\fR
386 events (eg when \fBiodepth_batch_complete=0\fR).
389 POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
392 Solaris native asynchronous I/O.
395 Windows native asynchronous I/O.
398 File is memory mapped with \fImmap\fR\|(2) and data copied using
402 \fIsplice\fR\|(2) is used to transfer the data and \fIvmsplice\fR\|(2) to
403 transfer data from user-space to the kernel.
406 Use the syslet system calls to make regular read/write asynchronous.
409 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
410 the target is an sg character device, we use \fIread\fR\|(2) and
411 \fIwrite\fR\|(2) for asynchronous I/O.
414 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
415 itself and for debugging and testing purposes.
418 Transfer over the network. \fBfilename\fR must be set appropriately to
419 `\fIhost\fR,\fIport\fR,\fItype\fR' regardless of data direction. \fItype\fR
420 is one of \fBtcp\fR, \fBudp\fR, or \fBunix\fR. For UNIX domain sockets,
421 the \fIhost\fR parameter is a file system path.
424 Like \fBnet\fR, but uses \fIsplice\fR\|(2) and \fIvmsplice\fR\|(2) to map data
428 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
429 \fBcpucycles\fR parameters.
432 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
433 approach to asycnronous I/O.
435 See <http://www.xmailserver.org/guasi\-lib.html>.
438 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
439 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
442 Loads an external I/O engine object file. Append the engine filename as
447 .BI iodepth \fR=\fPint
448 Number of I/O units to keep in flight against the file. Note that increasing
449 iodepth beyond 1 will not affect synchronous ioengines (except for small
450 degress when verify_async is in use). Even async engines my impose OS
451 restrictions causing the desired depth not to be achieved. This may happen on
452 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
453 not async on that OS. Keep an eye on the IO depth distribution in the
454 fio output to verify that the achieved depth is as expected. Default: 1.
456 .BI iodepth_batch \fR=\fPint
457 Number of I/Os to submit at once. Default: \fBiodepth\fR.
459 .BI iodepth_batch_complete \fR=\fPint
460 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
461 means that we'll ask for a minimum of 1 IO in the retrieval process from the
462 kernel. The IO retrieval will go on until we hit the limit set by
463 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
464 completed events before queuing more IO. This helps reduce IO latency, at the
465 cost of more retrieval system calls.
467 .BI iodepth_low \fR=\fPint
468 Low watermark indicating when to start filling the queue again. Default:
471 .BI direct \fR=\fPbool
472 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
474 .BI buffered \fR=\fPbool
475 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
478 .BI offset \fR=\fPint
479 Offset in the file to start I/O. Data before the offset will not be touched.
482 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
483 0, don't sync. Default: 0.
485 .BI fdatasync \fR=\fPint
486 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
487 data parts of the file. Default: 0.
489 .BI sync_file_range \fR=\fPstr:int
490 Use sync_file_range() for every \fRval\fP number of write operations. Fio will
491 track range of writes that have happened since the last sync_file_range() call.
492 \fRstr\fP can currently be one or more of:
496 SYNC_FILE_RANGE_WAIT_BEFORE
499 SYNC_FILE_RANGE_WRITE
502 SYNC_FILE_RANGE_WRITE
506 So if you do sync_file_range=wait_before,write:8, fio would use
507 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
508 Also see the sync_file_range(2) man page. This option is Linux specific.
510 .BI overwrite \fR=\fPbool
511 If writing, setup the file first and do overwrites. Default: false.
513 .BI end_fsync \fR=\fPbool
514 Sync file contents when job exits. Default: false.
516 .BI fsync_on_close \fR=\fPbool
517 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
518 it will happen on every close, not just at the end of the job. Default: false.
520 .BI rwmixcycle \fR=\fPint
521 How many milliseconds before switching between reads and writes for a mixed
522 workload. Default: 500ms.
524 .BI rwmixread \fR=\fPint
525 Percentage of a mixed workload that should be reads. Default: 50.
527 .BI rwmixwrite \fR=\fPint
528 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
529 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
530 overrides the first. This may interfere with a given rate setting, if fio is
531 asked to limit reads or writes to a certain rate. If that is the case, then
532 the distribution may be skewed. Default: 50.
535 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
536 this parameter is given, a new offset will be chosen without looking at past
537 I/O history. This parameter is mutually exclusive with \fBverify\fR.
539 .BI softrandommap \fR=\fPbool
540 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
541 fails to allocate the map, if this option is set it will continue without a
542 random block map. As coverage will not be as complete as with random maps, this
543 option is disabled by default.
546 Run job with given nice value. See \fInice\fR\|(2).
549 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
552 .BI prioclass \fR=\fPint
553 Set I/O priority class. See \fIionice\fR\|(1).
555 .BI thinktime \fR=\fPint
556 Stall job for given number of microseconds between issuing I/Os.
558 .BI thinktime_spin \fR=\fPint
559 Pretend to spend CPU time for given number of microseconds, sleeping the rest
560 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
562 .BI thinktime_blocks \fR=\fPint
563 Number of blocks to issue before waiting \fBthinktime\fR microseconds.
567 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
568 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
569 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
570 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
571 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
572 limit writes (to 500KB/sec), the latter will only limit reads.
574 .BI ratemin \fR=\fPint
575 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
576 Failing to meet this requirement will cause the job to exit. The same format
577 as \fBrate\fR is used for read vs write separation.
579 .BI rate_iops \fR=\fPint
580 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
581 specified independently of bandwidth. The same format as \fBrate\fR is used for
582 read vs write seperation. If \fBblocksize\fR is a range, the smallest block
583 size is used as the metric.
585 .BI rate_iops_min \fR=\fPint
586 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
587 is used for read vs write seperation.
589 .BI ratecycle \fR=\fPint
590 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
591 milliseconds. Default: 1000ms.
593 .BI cpumask \fR=\fPint
594 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
595 may run on. See \fBsched_setaffinity\fR\|(2).
597 .BI cpus_allowed \fR=\fPstr
598 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
600 .BI startdelay \fR=\fPint
601 Delay start of job for the specified number of seconds.
603 .BI runtime \fR=\fPint
604 Terminate processing after the specified number of seconds.
607 If given, run for the specified \fBruntime\fR duration even if the files are
608 completely read or written. The same workload will be repeated as many times
609 as \fBruntime\fR allows.
611 .BI ramp_time \fR=\fPint
612 If set, fio will run the specified workload for this amount of time before
613 logging any performance numbers. Useful for letting performance settle before
614 logging results, thus minimizing the runtime required for stable results. Note
615 that the \fBramp_time\fR is considered lead in time for a job, thus it will
616 increase the total runtime if a special timeout or runtime is specified.
618 .BI invalidate \fR=\fPbool
619 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
622 Use synchronous I/O for buffered writes. For the majority of I/O engines,
623 this means using O_SYNC. Default: false.
625 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
626 Allocation method for I/O unit buffer. Allowed values are:
631 Allocate memory with \fImalloc\fR\|(3).
634 Use shared memory buffers allocated through \fIshmget\fR\|(2).
637 Same as \fBshm\fR, but use huge pages as backing.
640 Use \fImmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
641 is given after the option in the format `:\fIfile\fR'.
644 Same as \fBmmap\fR, but use huge files as backing.
647 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
648 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
649 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
650 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
651 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
652 and the documentation for that. Normally you just need to echo an appropriate
653 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
657 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
658 This indiciates the memory alignment of the IO memory buffers. Note that the
659 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
660 the alignment of the following buffers are given by the \fBbs\fR used. In
661 other words, if using a \fBbs\fR that is a multiple of the page sized in the
662 system, all buffers will be aligned to this value. If using a \fBbs\fR that
663 is not page aligned, the alignment of subsequent IO memory buffers is the
664 sum of the \fBiomem_align\fR and \fBbs\fR used.
666 .BI hugepage\-size \fR=\fPint
667 Defines the size of a huge page. Must be at least equal to the system setting.
668 Should be a multiple of 1MB. Default: 4MB.
671 Terminate all jobs when one finishes. Default: wait for each job to finish.
673 .BI bwavgtime \fR=\fPint
674 Average bandwidth calculations over the given time in milliseconds. Default:
677 .BI iopsavgtime \fR=\fPint
678 Average IOPS calculations over the given time in milliseconds. Default:
681 .BI create_serialize \fR=\fPbool
682 If true, serialize file creation for the jobs. Default: true.
684 .BI create_fsync \fR=\fPbool
685 \fIfsync\fR\|(2) data file after creation. Default: true.
687 .BI create_on_open \fR=\fPbool
688 If true, the files are not created until they are opened for IO by the job.
690 .BI pre_read \fR=\fPbool
691 If this is given, files will be pre-read into memory before starting the given
692 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
693 pointless to pre-read and then drop the cache. This will only work for IO
694 engines that are seekable, since they allow you to read the same data
695 multiple times. Thus it will not work on eg network or splice IO.
697 .BI unlink \fR=\fPbool
698 Unlink job files when done. Default: false.
701 Specifies the number of iterations (runs of the same workload) of this job.
704 .BI do_verify \fR=\fPbool
705 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
708 .BI verify \fR=\fPstr
709 Method of verifying file contents after each iteration of the job. Allowed
714 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1
715 Store appropriate checksum in the header of each block. crc32c-intel is
716 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
717 not supported by the system.
720 Write extra information about each I/O (timestamp, block number, etc.). The
721 block number is verified. See \fBverify_pattern\fR as well.
724 Pretend to verify. Used for testing internals.
727 This option can be used for repeated burn-in tests of a system to make sure
728 that the written data is also correctly read back. If the data direction given
729 is a read or random read, fio will assume that it should verify a previously
730 written file. If the data direction includes any form of write, the verify will
731 be of the newly written data.
734 .BI verify_sort \fR=\fPbool
735 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
736 read them back in a sorted manner. Default: true.
738 .BI verify_offset \fR=\fPint
739 Swap the verification header with data somewhere else in the block before
740 writing. It is swapped back before verifying.
742 .BI verify_interval \fR=\fPint
743 Write the verification header for this number of bytes, which should divide
744 \fBblocksize\fR. Default: \fBblocksize\fR.
746 .BI verify_pattern \fR=\fPstr
747 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
748 with totally random bytes, but sometimes it's interesting to fill with a known
749 pattern for io verification purposes. Depending on the width of the pattern,
750 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
751 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
752 has to be a hex number that starts with either "0x" or "0X". Use with
755 .BI verify_fatal \fR=\fPbool
756 If true, exit the job on the first observed verification failure. Default:
759 .BI verify_dump \fR=\fPbool
760 If set, dump the contents of both the original data block and the data block we
761 read off disk to files. This allows later analysis to inspect just what kind of
762 data corruption occurred. On by default.
764 .BI verify_async \fR=\fPint
765 Fio will normally verify IO inline from the submitting thread. This option
766 takes an integer describing how many async offload threads to create for IO
767 verification instead, causing fio to offload the duty of verifying IO contents
768 to one or more separate threads. If using this offload option, even sync IO
769 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
770 allows them to have IO in flight while verifies are running.
772 .BI verify_async_cpus \fR=\fPstr
773 Tell fio to set the given CPU affinity on the async IO verification threads.
774 See \fBcpus_allowed\fP for the format used.
776 .BI verify_backlog \fR=\fPint
777 Fio will normally verify the written contents of a job that utilizes verify
778 once that job has completed. In other words, everything is written then
779 everything is read back and verified. You may want to verify continually
780 instead for a variety of reasons. Fio stores the meta data associated with an
781 IO block in memory, so for large verify workloads, quite a bit of memory would
782 be used up holding this meta data. If this option is enabled, fio will write
783 only N blocks before verifying these blocks.
785 .BI verify_backlog_batch \fR=\fPint
786 Control how many blocks fio will verify if verify_backlog is set. If not set,
787 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
788 read back and verified). If \fBverify_backlog_batch\fR is less than
789 \fBverify_backlog\fR then not all blocks will be verified, if
790 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
791 will be verified more than once.
793 .B stonewall "\fR,\fP wait_for_previous"
794 Wait for preceding jobs in the job file to exit before starting this one.
795 \fBstonewall\fR implies \fBnew_group\fR.
798 Start a new reporting group. If not given, all jobs in a file will be part
799 of the same reporting group, unless separated by a stonewall.
801 .BI numjobs \fR=\fPint
802 Number of clones (processes/threads performing the same workload) of this job.
806 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
810 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
811 with \fBfork\fR\|(2).
813 .BI zonesize \fR=\fPint
814 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
816 .BI zoneskip \fR=\fPint
817 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
820 .BI write_iolog \fR=\fPstr
821 Write the issued I/O patterns to the specified file. Specify a separate file
822 for each job, otherwise the iologs will be interspersed and the file may be
825 .BI read_iolog \fR=\fPstr
826 Replay the I/O patterns contained in the specified file generated by
827 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
829 .BI replay_no_stall \fR=\fPint
830 While replaying I/O patterns using \fBread_iolog\fR the default behavior
831 attempts to respect timing information between I/Os. Enabling
832 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
833 still respecting ordering.
835 .BI replay_redirect \fR=\fPstr
836 While replaying I/O patterns using \fBread_iolog\fR the default behavior
837 is to replay the IOPS onto the major/minor device that each IOP was recorded
838 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
839 single specified device regardless of the device it was recorded from.
841 .BI write_bw_log \fR=\fPstr
842 If given, write a bandwidth log of the jobs in this job file. Can be used to
843 store data of the bandwidth of the jobs in their lifetime. The included
844 fio_generate_plots script uses gnuplot to turn these text files into nice
845 graphs. See \fBwrite_log_log\fR for behaviour of given filename. For this
846 option, the postfix is _bw.log.
848 .BI write_lat_log \fR=\fPstr
849 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
850 filename is given with this option, the default filename of "jobname_type.log"
851 is used. Even if the filename is given, fio will still append the type of log.
853 .BI write_iops_log \fR=\fPstr
854 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
855 option, the default filename of "jobname_type.log" is used. Even if the
856 filename is given, fio will still append the type of log.
858 .BI disable_lat \fR=\fPbool
859 Disable measurements of total latency numbers. Useful only for cutting
860 back the number of calls to gettimeofday, as that does impact performance at
861 really high IOPS rates. Note that to really get rid of a large amount of these
862 calls, this option must be used with disable_slat and disable_bw as well.
864 .BI disable_clat \fR=\fPbool
865 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
867 .BI disable_slat \fR=\fPbool
868 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
870 .BI disable_bw_measurement \fR=\fPbool
871 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
873 .BI lockmem \fR=\fPint
874 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
875 simulate a smaller amount of memory.
877 .BI exec_prerun \fR=\fPstr
878 Before running the job, execute the specified command with \fBsystem\fR\|(3).
880 .BI exec_postrun \fR=\fPstr
881 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
883 .BI ioscheduler \fR=\fPstr
884 Attempt to switch the device hosting the file to the specified I/O scheduler.
886 .BI cpuload \fR=\fPint
887 If the job is a CPU cycle-eater, attempt to use the specified percentage of
890 .BI cpuchunks \fR=\fPint
891 If the job is a CPU cycle-eater, split the load into cycles of the
892 given time in milliseconds.
894 .BI disk_util \fR=\fPbool
895 Generate disk utilization statistics if the platform supports it. Default: true.
897 .BI gtod_reduce \fR=\fPbool
898 Enable all of the gettimeofday() reducing options (disable_clat, disable_slat,
899 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
900 gettimeofday() call count. With this option enabled, we only do about 0.4% of
901 the gtod() calls we would have done if all time keeping was enabled.
903 .BI gtod_cpu \fR=\fPint
904 Sometimes it's cheaper to dedicate a single thread of execution to just getting
905 the current time. Fio (and databases, for instance) are very intensive on
906 gettimeofday() calls. With this option, you can set one CPU aside for doing
907 nothing but logging current time to a shared memory location. Then the other
908 threads/processes that run IO workloads need only copy that segment, instead of
909 entering the kernel with a gettimeofday() call. The CPU set aside for doing
910 these time calls will be excluded from other uses. Fio will manually clear it
911 from the CPU mask of other jobs.
913 .BI cgroup \fR=\fPstr
914 Add job to this control group. If it doesn't exist, it will be created.
915 The system must have a mounted cgroup blkio mount point for this to work. If
916 your system doesn't have it mounted, you can do so with:
918 # mount \-t cgroup \-o blkio none /cgroup
920 .BI cgroup_weight \fR=\fPint
921 Set the weight of the cgroup to this value. See the documentation that comes
922 with the kernel, allowed values are in the range of 100..1000.
924 .BI cgroup_nodelete \fR=\fPbool
925 Normally fio will delete the cgroups it has created after the job completion.
926 To override this behavior and to leave cgroups around after the job completion,
927 set cgroup_nodelete=1. This can be useful if one wants to inspect various
928 cgroup files after job completion. Default: false
931 Instead of running as the invoking user, set the user ID to this value before
932 the thread/process does any work.
935 Set group ID, see \fBuid\fR.
937 .BI clat_percentiles \fR=\fPbool
938 Enable the reporting of percentiles of completion latencies.
940 .BI percentile_list \fR=\fPfloat_list
941 Overwrite the default list of percentiles for completion
942 latencies. Each number is a floating number in the range (0,100], and
943 the maximum length of the list is 20. Use ':' to separate the
944 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
945 report the values of completion latency below which 99.5% and 99.9% of
946 the observed latencies fell, respectively.
948 While running, \fBfio\fR will display the status of the created jobs. For
952 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
955 The characters in the first set of brackets denote the current status of each
956 threads. The possible values are:
962 Setup but not started.
968 Initialized, waiting.
971 Running, doing sequential reads.
974 Running, doing random reads.
977 Running, doing sequential writes.
980 Running, doing random writes.
983 Running, doing mixed sequential reads/writes.
986 Running, doing mixed random reads/writes.
989 Running, currently waiting for \fBfsync\fR\|(2).
992 Running, verifying written data.
995 Exited, not reaped by main thread.
998 Exited, thread reaped.
1002 The second set of brackets shows the estimated completion percentage of
1003 the current group. The third set shows the read and write I/O rate,
1004 respectively. Finally, the estimated run time of the job is displayed.
1006 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1007 for each thread, each group of threads, and each disk, in that order.
1009 Per-thread statistics first show the threads client number, group-id, and
1010 error code. The remaining figures are as follows:
1014 Number of megabytes of I/O performed.
1017 Average data rate (bandwidth).
1023 Submission latency minimum, maximum, average and standard deviation. This is
1024 the time it took to submit the I/O.
1027 Completion latency minimum, maximum, average and standard deviation. This
1028 is the time between submission and completion.
1031 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1032 and standard deviation.
1035 CPU usage statistics. Includes user and system time, number of context switches
1036 this thread went through and number of major and minor page faults.
1039 Distribution of I/O depths. Each depth includes everything less than (or equal)
1040 to it, but greater than the previous depth.
1043 Number of read/write requests issued, and number of short read/write requests.
1046 Distribution of I/O completion latencies. The numbers follow the same pattern
1050 The group statistics show:
1055 Number of megabytes I/O performed.
1058 Aggregate bandwidth of threads in the group.
1061 Minimum average bandwidth a thread saw.
1064 Maximum average bandwidth a thread saw.
1067 Shortest runtime of threads in the group.
1070 Longest runtime of threads in the group.
1074 Finally, disk statistics are printed with reads first:
1079 Number of I/Os performed by all groups.
1082 Number of merges in the I/O scheduler.
1085 Number of ticks we kept the disk busy.
1088 Total time spent in the disk queue.
1095 If the \fB\-\-minimal\fR option is given, the results will be printed in a
1096 semicolon-delimited format suitable for scripted use - a job description
1097 (if provided) follows on a new line. Note that the first
1098 number in the line is the version number. If the output has to be changed
1099 for some reason, this number will be incremented by 1 to signify that
1100 change. The fields are:
1103 .B version, jobname, groupid, error
1107 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, runtime \fR(ms)\fP
1111 .B min, max, mean, standard deviation
1115 .B min, max, mean, standard deviation
1119 .B min, max, mean, standard deviation
1123 .B min, max, aggregate percentage of total, mean, standard deviation
1129 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, runtime \fR(ms)\fP
1133 .B min, max, mean, standard deviation
1137 .B min, max, mean, standard deviation
1141 .B min, max, mean, standard deviation
1145 .B min, max, aggregate percentage of total, mean, standard deviation
1151 .B user, system, context switches, major page faults, minor page faults
1154 IO depth distribution:
1156 .B <=1, 2, 4, 8, 16, 32, >=64
1159 IO latency distribution:
1163 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1167 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1171 Error Info (dependent on continue_on_error, default off):
1173 .B total # errors, first error code
1176 .B text description (if provided in config - appears on newline)
1180 was written by Jens Axboe <jens.axboe@oracle.com>,
1181 now Jens Axboe <jaxboe@fusionio.com>.
1183 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1184 on documentation by Jens Axboe.
1185 .SH "REPORTING BUGS"
1186 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1189 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1191 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob