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 Job files are in `ini' format. They consist of one or more
58 job definitions, which begin with a job name in square brackets and
59 extend to the next job name. The job name can be any ASCII string
60 except `global', which has a special meaning. Following the job name is
61 a sequence of zero or more parameters, one per line, that define the
62 behavior of the job. Any line starting with a `;' or `#' character is
63 considered a comment and ignored.
65 If \fIjobfile\fR is specified as `-', the job file will be read from
68 The global section contains default parameters for jobs specified in the
69 job file. A job is only affected by global sections residing above it,
70 and there may be any number of global sections. Specific job definitions
71 may override any parameter set in global sections.
74 Some parameters may take arguments of a specific type. The types used are:
77 String: a sequence of alphanumeric characters.
80 SI integer: a whole number, possibly containing a suffix denoting the base unit
81 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
82 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
83 respectively. The suffix is not case sensitive. If prefixed with '0x', the
84 value is assumed to be base 16 (hexadecimal). A suffix may include a trailing 'b',
85 for instance 'kb' is identical to 'k'. You can specify a base 10 value
86 by using 'KiB', 'MiB', 'GiB', etc. This is useful for disk drives where
87 values are often given in base 10 values. Specifying '30GiB' will get you
91 Boolean: a true or false value. `0' denotes false, `1' denotes true.
94 Integer range: a range of integers specified in the format
95 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
96 \fIupper\fR may contain a suffix as described above. If an option allows two
97 sets of ranges, they are separated with a `,' or `/' character. For example:
102 May be used to override the job name. On the command line, this parameter
103 has the special purpose of signalling the start of a new job.
105 .BI description \fR=\fPstr
106 Human-readable description of the job. It is printed when the job is run, but
107 otherwise has no special purpose.
109 .BI directory \fR=\fPstr
110 Prefix filenames with this directory. Used to place files in a location other
113 .BI filename \fR=\fPstr
115 normally makes up a file name based on the job name, thread number, and file
116 number. If you want to share files between threads in a job or several jobs,
117 specify a \fIfilename\fR for each of them to override the default. If the I/O
118 engine used is `net', \fIfilename\fR is the host and port to connect to in the
119 format \fIhost\fR/\fIport\fR. If the I/O engine is file-based, you can specify
120 a number of files by separating the names with a `:' character. `\-' is a
121 reserved name, meaning stdin or stdout, depending on the read/write direction
124 .BI lockfile \fR=\fPstr
125 Fio defaults to not locking any files before it does IO to them. If a file or
126 file descriptor is shared, fio can serialize IO to that file to make the end
127 result consistent. This is usual for emulating real workloads that share files.
133 No locking. This is the default.
136 Only one thread or process may do IO at the time, excluding all others.
139 Read-write locking on the file. Many readers may access the file at the same
140 time, but writes get exclusive access.
143 The option may be post-fixed with a lock batch number. If set, then each
144 thread/process may do that amount of IOs to the file before giving up the lock.
145 Since lock acquisition is expensive, batching the lock/unlocks will speed up IO.
148 .BI opendir \fR=\fPstr
149 Recursively open any files below directory \fIstr\fR.
151 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
152 Type of I/O pattern. Accepted values are:
169 Mixed sequential reads and writes.
172 Mixed random reads and writes.
175 For mixed I/O, the default split is 50/50. For certain types of io the result
176 may still be skewed a bit, since the speed may be different. It is possible to
177 specify a number of IO's to do before getting a new offset, this is one by
178 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
179 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
180 value of 8. See the \fBrw_sequencer\fR option.
183 .BI rw_sequencer \fR=\fPstr
184 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
185 then this option controls how that number modifies the IO offset being
186 generated. Accepted values are:
191 Generate sequential offset
194 Generate the same offset
197 \fBsequential\fR is only useful for random IO, where fio would normally
198 generate a new random offset for every IO. If you append eg 8 to randread, you
199 would get a new random offset for every 8 IO's. The result would be a seek for
200 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
201 that. As sequential IO is already sequential, setting \fBsequential\fR for that
202 would not result in any differences. \fBidentical\fR behaves in a similar
203 fashion, except it sends the same offset 8 number of times before generating a
208 .BI kb_base \fR=\fPint
209 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
210 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
211 reasons. Allow values are 1024 or 1000, with 1024 being the default.
213 .BI randrepeat \fR=\fPbool
214 Seed the random number generator in a predictable way so results are repeatable
215 across runs. Default: true.
217 .BI use_os_rand \fR=\fPbool
218 Fio can either use the random generator supplied by the OS to generator random
219 offsets, or it can use it's own internal generator (based on Tausworthe).
220 Default is to use the internal generator, which is often of better quality and
221 faster. Default: false.
223 .BI fallocate \fR=\fPstr
224 Whether pre-allocation is performed when laying down files. Accepted values
230 Do not pre-allocate space.
233 Pre-allocate via posix_fallocate().
236 Pre-allocate via fallocate() with FALLOC_FL_KEEP_SIZE set.
239 Backward-compatible alias for 'none'.
242 Backward-compatible alias for 'posix'.
245 May not be available on all supported platforms. 'keep' is only
246 available on Linux. If using ZFS on Solaris this must be set to 'none'
247 because ZFS doesn't support it. Default: 'posix'.
250 .BI fadvise_hint \fR=\fPbool
251 Disable use of \fIposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
252 are likely to be issued. Default: true.
255 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
256 been transfered, unless limited by other options (\fBruntime\fR, for instance).
257 Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
258 divided between the available files for the job. If not set, fio will use the
259 full size of the given files or devices. If the the files do not exist, size
260 must be given. It is also possible to give size as a percentage between 1 and
261 100. If size=20% is given, fio will use 20% of the full size of the given files
264 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
265 Sets size to something really large and waits for ENOSPC (no space left on
266 device) as the terminating condition. Only makes sense with sequential write.
267 For a read workload, the mount point will be filled first then IO started on
268 the result. This option doesn't make sense if operating on a raw device node,
269 since the size of that is already known by the file system. Additionally,
270 writing beyond end-of-device will not return ENOSPC there.
272 .BI filesize \fR=\fPirange
273 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
274 for files at random within the given range, limited to \fBsize\fR in total (if
275 that is given). If \fBfilesize\fR is not specified, each created file is the
278 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
279 Block size for I/O units. Default: 4k. Values for reads and writes can be
280 specified separately in the format \fIread\fR,\fIwrite\fR, either of
281 which may be empty to leave that value at its default.
283 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
284 Specify a range of I/O block sizes. The issued I/O unit will always be a
285 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
286 to both reads and writes if only one range is given, but can be specified
287 separately with a comma seperating the values. Example: bsrange=1k-4k,2k-8k.
288 Also (see \fBblocksize\fR).
290 .BI bssplit \fR=\fPstr
291 This option allows even finer grained control of the block sizes issued,
292 not just even splits between them. With this option, you can weight various
293 block sizes for exact control of the issued IO for a job that has mixed
294 block sizes. The format of the option is bssplit=blocksize/percentage,
295 optionally adding as many definitions as needed separated by a colon.
296 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
297 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
298 splits to reads and writes. The format is identical to what the
299 \fBbs\fR option accepts, the read and write parts are separated with a
302 .B blocksize_unaligned\fR,\fP bs_unaligned
303 If set, any size in \fBblocksize_range\fR may be used. This typically won't
304 work with direct I/O, as that normally requires sector alignment.
306 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
307 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
308 the minimum blocksize given. Minimum alignment is typically 512b
309 for using direct IO, though it usually depends on the hardware block size.
310 This option is mutually exclusive with using a random map for files, so it
311 will turn off that option.
314 Initialise buffers with all zeros. Default: fill buffers with random data.
317 If this option is given, fio will refill the IO buffers on every submit. The
318 default is to only fill it at init time and reuse that data. Only makes sense
319 if zero_buffers isn't specified, naturally. If data verification is enabled,
320 refill_buffers is also automatically enabled.
322 .BI nrfiles \fR=\fPint
323 Number of files to use for this job. Default: 1.
325 .BI openfiles \fR=\fPint
326 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
328 .BI file_service_type \fR=\fPstr
329 Defines how files to service are selected. The following types are defined:
334 Choose a file at random
337 Round robin over open files (default).
339 Do each file in the set sequentially.
342 The number of I/Os to issue before switching a new file can be specified by
343 appending `:\fIint\fR' to the service type.
346 .BI ioengine \fR=\fPstr
347 Defines how the job issues I/O. The following types are defined:
352 Basic \fIread\fR\|(2) or \fIwrite\fR\|(2) I/O. \fIfseek\fR\|(2) is used to
353 position the I/O location.
356 Basic \fIpread\fR\|(2) or \fIpwrite\fR\|(2) I/O.
359 Basic \fIreadv\fR\|(2) or \fIwritev\fR\|(2) I/O. Will emulate queuing by
360 coalescing adjacents IOs into a single submission.
363 Linux native asynchronous I/O.
366 POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
369 Solaris native asynchronous I/O.
372 Windows native asynchronous I/O.
375 File is memory mapped with \fImmap\fR\|(2) and data copied using
379 \fIsplice\fR\|(2) is used to transfer the data and \fIvmsplice\fR\|(2) to
380 transfer data from user-space to the kernel.
383 Use the syslet system calls to make regular read/write asynchronous.
386 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
387 the target is an sg character device, we use \fIread\fR\|(2) and
388 \fIwrite\fR\|(2) for asynchronous I/O.
391 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
392 itself and for debugging and testing purposes.
395 Transfer over the network. \fBfilename\fR must be set appropriately to
396 `\fIhost\fR/\fIport\fR' regardless of data direction. If receiving, only the
397 \fIport\fR argument is used.
400 Like \fBnet\fR, but uses \fIsplice\fR\|(2) and \fIvmsplice\fR\|(2) to map data
404 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
405 \fBcpucycles\fR parameters.
408 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
409 approach to asycnronous I/O.
411 See <http://www.xmailserver.org/guasi\-lib.html>.
414 Loads an external I/O engine object file. Append the engine filename as
419 .BI iodepth \fR=\fPint
420 Number of I/O units to keep in flight against the file. Note that increasing
421 iodepth beyond 1 will not affect synchronous ioengines (except for small
422 degress when verify_async is in use). Even async engines my impose OS
423 restrictions causing the desired depth not to be achieved. This may happen on
424 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
425 not async on that OS. Keep an eye on the IO depth distribution in the
426 fio output to verify that the achieved depth is as expected. Default: 1.
428 .BI iodepth_batch \fR=\fPint
429 Number of I/Os to submit at once. Default: \fBiodepth\fR.
431 .BI iodepth_batch_complete \fR=\fPint
432 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
433 means that we'll ask for a minimum of 1 IO in the retrieval process from the
434 kernel. The IO retrieval will go on until we hit the limit set by
435 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
436 completed events before queuing more IO. This helps reduce IO latency, at the
437 cost of more retrieval system calls.
439 .BI iodepth_low \fR=\fPint
440 Low watermark indicating when to start filling the queue again. Default:
443 .BI direct \fR=\fPbool
444 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
446 .BI buffered \fR=\fPbool
447 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
450 .BI offset \fR=\fPint
451 Offset in the file to start I/O. Data before the offset will not be touched.
454 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
455 0, don't sync. Default: 0.
457 .BI fdatasync \fR=\fPint
458 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
459 data parts of the file. Default: 0.
461 .BI sync_file_range \fR=\fPstr:int
462 Use sync_file_range() for every \fRval\fP number of write operations. Fio will
463 track range of writes that have happened since the last sync_file_range() call.
464 \fRstr\fP can currently be one or more of:
468 SYNC_FILE_RANGE_WAIT_BEFORE
471 SYNC_FILE_RANGE_WRITE
474 SYNC_FILE_RANGE_WRITE
478 So if you do sync_file_range=wait_before,write:8, fio would use
479 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
480 Also see the sync_file_range(2) man page. This option is Linux specific.
482 .BI overwrite \fR=\fPbool
483 If writing, setup the file first and do overwrites. Default: false.
485 .BI end_fsync \fR=\fPbool
486 Sync file contents when job exits. Default: false.
488 .BI fsync_on_close \fR=\fPbool
489 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
490 it will happen on every close, not just at the end of the job. Default: false.
492 .BI rwmixcycle \fR=\fPint
493 How many milliseconds before switching between reads and writes for a mixed
494 workload. Default: 500ms.
496 .BI rwmixread \fR=\fPint
497 Percentage of a mixed workload that should be reads. Default: 50.
499 .BI rwmixwrite \fR=\fPint
500 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
501 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
502 overrides the first. This may interfere with a given rate setting, if fio is
503 asked to limit reads or writes to a certain rate. If that is the case, then
504 the distribution may be skewed. Default: 50.
507 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
508 this parameter is given, a new offset will be chosen without looking at past
509 I/O history. This parameter is mutually exclusive with \fBverify\fR.
512 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
513 fails to allocate the map, if this option is set it will continue without a
514 random block map. As coverage will not be as complete as with random maps, this
515 option is disabled by default.
518 Run job with given nice value. See \fInice\fR\|(2).
521 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
524 .BI prioclass \fR=\fPint
525 Set I/O priority class. See \fIionice\fR\|(1).
527 .BI thinktime \fR=\fPint
528 Stall job for given number of microseconds between issuing I/Os.
530 .BI thinktime_spin \fR=\fPint
531 Pretend to spend CPU time for given number of microseconds, sleeping the rest
532 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
534 .BI thinktime_blocks \fR=\fPint
535 Number of blocks to issue before waiting \fBthinktime\fR microseconds.
539 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
540 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
541 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
542 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
543 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
544 limit writes (to 500KB/sec), the latter will only limit reads.
546 .BI ratemin \fR=\fPint
547 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
548 Failing to meet this requirement will cause the job to exit. The same format
549 as \fBrate\fR is used for read vs write separation.
551 .BI rate_iops \fR=\fPint
552 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
553 specified independently of bandwidth. The same format as \fBrate\fR is used for
554 read vs write seperation. If \fBblocksize\fR is a range, the smallest block
555 size is used as the metric.
557 .BI rate_iops_min \fR=\fPint
558 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
559 is used for read vs write seperation.
561 .BI ratecycle \fR=\fPint
562 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
563 milliseconds. Default: 1000ms.
565 .BI cpumask \fR=\fPint
566 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
567 may run on. See \fBsched_setaffinity\fR\|(2).
569 .BI cpus_allowed \fR=\fPstr
570 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
572 .BI startdelay \fR=\fPint
573 Delay start of job for the specified number of seconds.
575 .BI runtime \fR=\fPint
576 Terminate processing after the specified number of seconds.
579 If given, run for the specified \fBruntime\fR duration even if the files are
580 completely read or written. The same workload will be repeated as many times
581 as \fBruntime\fR allows.
583 .BI ramp_time \fR=\fPint
584 If set, fio will run the specified workload for this amount of time before
585 logging any performance numbers. Useful for letting performance settle before
586 logging results, thus minimizing the runtime required for stable results. Note
587 that the \fBramp_time\fR is considered lead in time for a job, thus it will
588 increase the total runtime if a special timeout or runtime is specified.
590 .BI invalidate \fR=\fPbool
591 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
594 Use synchronous I/O for buffered writes. For the majority of I/O engines,
595 this means using O_SYNC. Default: false.
597 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
598 Allocation method for I/O unit buffer. Allowed values are:
603 Allocate memory with \fImalloc\fR\|(3).
606 Use shared memory buffers allocated through \fIshmget\fR\|(2).
609 Same as \fBshm\fR, but use huge pages as backing.
612 Use \fImmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
613 is given after the option in the format `:\fIfile\fR'.
616 Same as \fBmmap\fR, but use huge files as backing.
619 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
620 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
621 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
622 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
623 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
624 and the documentation for that. Normally you just need to echo an appropriate
625 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
629 .BI iomem_align \fR=\fPint
630 This indiciates the memory alignment of the IO memory buffers. Note that the
631 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
632 the alignment of the following buffers are given by the \fBbs\fR used. In
633 other words, if using a \fBbs\fR that is a multiple of the page sized in the
634 system, all buffers will be aligned to this value. If using a \fBbs\fR that
635 is not page aligned, the alignment of subsequent IO memory buffers is the
636 sum of the \fBiomem_align\fR and \fBbs\fR used.
638 .BI hugepage\-size \fR=\fPint
639 Defines the size of a huge page. Must be at least equal to the system setting.
640 Should be a multiple of 1MB. Default: 4MB.
643 Terminate all jobs when one finishes. Default: wait for each job to finish.
645 .BI bwavgtime \fR=\fPint
646 Average bandwidth calculations over the given time in milliseconds. Default:
649 .BI create_serialize \fR=\fPbool
650 If true, serialize file creation for the jobs. Default: true.
652 .BI create_fsync \fR=\fPbool
653 \fIfsync\fR\|(2) data file after creation. Default: true.
655 .BI create_on_open \fR=\fPbool
656 If true, the files are not created until they are opened for IO by the job.
658 .BI pre_read \fR=\fPbool
659 If this is given, files will be pre-read into memory before starting the given
660 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
661 pointless to pre-read and then drop the cache. This will only work for IO
662 engines that are seekable, since they allow you to read the same data
663 multiple times. Thus it will not work on eg network or splice IO.
665 .BI unlink \fR=\fPbool
666 Unlink job files when done. Default: false.
669 Specifies the number of iterations (runs of the same workload) of this job.
672 .BI do_verify \fR=\fPbool
673 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
676 .BI verify \fR=\fPstr
677 Method of verifying file contents after each iteration of the job. Allowed
682 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1
683 Store appropriate checksum in the header of each block. crc32c-intel is
684 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
685 not supported by the system.
688 Write extra information about each I/O (timestamp, block number, etc.). The
689 block number is verified. See \fBverify_pattern\fR as well.
692 Pretend to verify. Used for testing internals.
695 This option can be used for repeated burn-in tests of a system to make sure
696 that the written data is also correctly read back. If the data direction given
697 is a read or random read, fio will assume that it should verify a previously
698 written file. If the data direction includes any form of write, the verify will
699 be of the newly written data.
702 .BI verify_sort \fR=\fPbool
703 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
704 read them back in a sorted manner. Default: true.
706 .BI verify_offset \fR=\fPint
707 Swap the verification header with data somewhere else in the block before
708 writing. It is swapped back before verifying.
710 .BI verify_interval \fR=\fPint
711 Write the verification header for this number of bytes, which should divide
712 \fBblocksize\fR. Default: \fBblocksize\fR.
714 .BI verify_pattern \fR=\fPstr
715 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
716 with totally random bytes, but sometimes it's interesting to fill with a known
717 pattern for io verification purposes. Depending on the width of the pattern,
718 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
719 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
720 has to be a hex number that starts with either "0x" or "0X". Use with
723 .BI verify_fatal \fR=\fPbool
724 If true, exit the job on the first observed verification failure. Default:
727 .BI verify_dump \fR=\fPbool
728 If set, dump the contents of both the original data block and the data block we
729 read off disk to files. This allows later analysis to inspect just what kind of
730 data corruption occurred. On by default.
732 .BI verify_async \fR=\fPint
733 Fio will normally verify IO inline from the submitting thread. This option
734 takes an integer describing how many async offload threads to create for IO
735 verification instead, causing fio to offload the duty of verifying IO contents
736 to one or more separate threads. If using this offload option, even sync IO
737 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
738 allows them to have IO in flight while verifies are running.
740 .BI verify_async_cpus \fR=\fPstr
741 Tell fio to set the given CPU affinity on the async IO verification threads.
742 See \fBcpus_allowed\fP for the format used.
744 .BI verify_backlog \fR=\fPint
745 Fio will normally verify the written contents of a job that utilizes verify
746 once that job has completed. In other words, everything is written then
747 everything is read back and verified. You may want to verify continually
748 instead for a variety of reasons. Fio stores the meta data associated with an
749 IO block in memory, so for large verify workloads, quite a bit of memory would
750 be used up holding this meta data. If this option is enabled, fio will write
751 only N blocks before verifying these blocks.
753 .BI verify_backlog_batch \fR=\fPint
754 Control how many blocks fio will verify if verify_backlog is set. If not set,
755 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
756 read back and verified). If \fBverify_backlog_batch\fR is less than
757 \fBverify_backlog\fR then not all blocks will be verified, if
758 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
759 will be verified more than once.
762 Wait for preceding jobs in the job file to exit before starting this one.
763 \fBstonewall\fR implies \fBnew_group\fR.
766 Start a new reporting group. If not given, all jobs in a file will be part
767 of the same reporting group, unless separated by a stonewall.
769 .BI numjobs \fR=\fPint
770 Number of clones (processes/threads performing the same workload) of this job.
774 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
778 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
779 with \fBfork\fR\|(2).
781 .BI zonesize \fR=\fPint
782 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
784 .BI zoneskip \fR=\fPint
785 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
788 .BI write_iolog \fR=\fPstr
789 Write the issued I/O patterns to the specified file. Specify a separate file
790 for each job, otherwise the iologs will be interspersed and the file may be
793 .BI read_iolog \fR=\fPstr
794 Replay the I/O patterns contained in the specified file generated by
795 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
797 .BI replay_no_stall \fR=\fPint
798 While replaying I/O patterns using \fBread_iolog\fR the default behavior
799 attempts to respect timing information between I/Os. Enabling
800 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
801 still respecting ordering.
803 .BI replay_redirect \fR=\fPstr
804 While replaying I/O patterns using \fBread_iolog\fR the default behavior
805 is to replay the IOPS onto the major/minor device that each IOP was recorded
806 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
807 single specified device regardless of the device it was recorded from.
809 .B write_bw_log \fR=\fPstr
810 If given, write a bandwidth log of the jobs in this job file. Can be used to
811 store data of the bandwidth of the jobs in their lifetime. The included
812 fio_generate_plots script uses gnuplot to turn these text files into nice
813 graphs. See \fBwrite_log_log\fR for behaviour of given filename. For this
814 option, the postfix is _bw.log.
816 .B write_lat_log \fR=\fPstr
817 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
818 filename is given with this option, the default filename of "jobname_type.log"
819 is used. Even if the filename is given, fio will still append the type of log.
821 .B disable_lat \fR=\fPbool
822 Disable measurements of total latency numbers. Useful only for cutting
823 back the number of calls to gettimeofday, as that does impact performance at
824 really high IOPS rates. Note that to really get rid of a large amount of these
825 calls, this option must be used with disable_slat and disable_bw as well.
827 .B disable_clat \fR=\fPbool
828 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
830 .B disable_slat \fR=\fPbool
831 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
833 .B disable_bw_measurement \fR=\fPbool
834 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
836 .BI lockmem \fR=\fPint
837 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
838 simulate a smaller amount of memory.
840 .BI exec_prerun \fR=\fPstr
841 Before running the job, execute the specified command with \fBsystem\fR\|(3).
843 .BI exec_postrun \fR=\fPstr
844 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
846 .BI ioscheduler \fR=\fPstr
847 Attempt to switch the device hosting the file to the specified I/O scheduler.
849 .BI cpuload \fR=\fPint
850 If the job is a CPU cycle-eater, attempt to use the specified percentage of
853 .BI cpuchunks \fR=\fPint
854 If the job is a CPU cycle-eater, split the load into cycles of the
855 given time in milliseconds.
857 .BI disk_util \fR=\fPbool
858 Generate disk utilization statistics if the platform supports it. Default: true.
860 .BI gtod_reduce \fR=\fPbool
861 Enable all of the gettimeofday() reducing options (disable_clat, disable_slat,
862 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
863 gettimeofday() call count. With this option enabled, we only do about 0.4% of
864 the gtod() calls we would have done if all time keeping was enabled.
866 .BI gtod_cpu \fR=\fPint
867 Sometimes it's cheaper to dedicate a single thread of execution to just getting
868 the current time. Fio (and databases, for instance) are very intensive on
869 gettimeofday() calls. With this option, you can set one CPU aside for doing
870 nothing but logging current time to a shared memory location. Then the other
871 threads/processes that run IO workloads need only copy that segment, instead of
872 entering the kernel with a gettimeofday() call. The CPU set aside for doing
873 these time calls will be excluded from other uses. Fio will manually clear it
874 from the CPU mask of other jobs.
876 .BI cgroup \fR=\fPstr
877 Add job to this control group. If it doesn't exist, it will be created.
878 The system must have a mounted cgroup blkio mount point for this to work. If
879 your system doesn't have it mounted, you can do so with:
881 # mount \-t cgroup \-o blkio none /cgroup
883 .BI cgroup_weight \fR=\fPint
884 Set the weight of the cgroup to this value. See the documentation that comes
885 with the kernel, allowed values are in the range of 100..1000.
887 .BI cgroup_nodelete \fR=\fPbool
888 Normally fio will delete the cgroups it has created after the job completion.
889 To override this behavior and to leave cgroups around after the job completion,
890 set cgroup_nodelete=1. This can be useful if one wants to inspect various
891 cgroup files after job completion. Default: false
894 Instead of running as the invoking user, set the user ID to this value before
895 the thread/process does any work.
898 Set group ID, see \fBuid\fR.
900 While running, \fBfio\fR will display the status of the created jobs. For
904 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
907 The characters in the first set of brackets denote the current status of each
908 threads. The possible values are:
914 Setup but not started.
920 Initialized, waiting.
923 Running, doing sequential reads.
926 Running, doing random reads.
929 Running, doing sequential writes.
932 Running, doing random writes.
935 Running, doing mixed sequential reads/writes.
938 Running, doing mixed random reads/writes.
941 Running, currently waiting for \fBfsync\fR\|(2).
944 Running, verifying written data.
947 Exited, not reaped by main thread.
950 Exited, thread reaped.
954 The second set of brackets shows the estimated completion percentage of
955 the current group. The third set shows the read and write I/O rate,
956 respectively. Finally, the estimated run time of the job is displayed.
958 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
959 for each thread, each group of threads, and each disk, in that order.
961 Per-thread statistics first show the threads client number, group-id, and
962 error code. The remaining figures are as follows:
966 Number of megabytes of I/O performed.
969 Average data rate (bandwidth).
975 Submission latency minimum, maximum, average and standard deviation. This is
976 the time it took to submit the I/O.
979 Completion latency minimum, maximum, average and standard deviation. This
980 is the time between submission and completion.
983 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
984 and standard deviation.
987 CPU usage statistics. Includes user and system time, number of context switches
988 this thread went through and number of major and minor page faults.
991 Distribution of I/O depths. Each depth includes everything less than (or equal)
992 to it, but greater than the previous depth.
995 Number of read/write requests issued, and number of short read/write requests.
998 Distribution of I/O completion latencies. The numbers follow the same pattern
1002 The group statistics show:
1007 Number of megabytes I/O performed.
1010 Aggregate bandwidth of threads in the group.
1013 Minimum average bandwidth a thread saw.
1016 Maximum average bandwidth a thread saw.
1019 Shortest runtime of threads in the group.
1022 Longest runtime of threads in the group.
1026 Finally, disk statistics are printed with reads first:
1031 Number of I/Os performed by all groups.
1034 Number of merges in the I/O scheduler.
1037 Number of ticks we kept the disk busy.
1040 Total time spent in the disk queue.
1047 If the \fB\-\-minimal\fR option is given, the results will be printed in a
1048 semicolon-delimited format suitable for scripted use - a job description
1049 (if provided) follows on a new line. Note that the first
1050 number in the line is the version number. If the output has to be changed
1051 for some reason, this number will be incremented by 1 to signify that
1052 change. The fields are:
1055 .B version, jobname, groupid, error
1059 .B KB I/O, bandwidth \fR(KB/s)\fP, runtime \fR(ms)\fP
1063 .B min, max, mean, standard deviation
1067 .B min, max, mean, standard deviation
1071 .B min, max, mean, standard deviation
1075 .B min, max, aggregate percentage of total, mean, standard deviation
1081 .B KB I/O, bandwidth \fR(KB/s)\fP, runtime \fR(ms)\fP
1085 .B min, max, mean, standard deviation
1089 .B min, max, mean, standard deviation
1093 .B min, max, mean, standard deviation
1097 .B min, max, aggregate percentage of total, mean, standard deviation
1103 .B user, system, context switches, major page faults, minor page faults
1106 IO depth distribution:
1108 .B <=1, 2, 4, 8, 16, 32, >=64
1111 IO latency distribution:
1115 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1119 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1123 Error Info (dependent on continue_on_error, default off):
1125 .B total # errors, first error code
1128 .B text description (if provided in config - appears on newline)
1132 was written by Jens Axboe <jens.axboe@oracle.com>,
1133 now Jens Axboe <jaxboe@fusionio.com>.
1135 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1136 on documentation by Jens Axboe.
1137 .SH "REPORTING BUGS"
1138 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1141 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1143 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob