-.TH fio 1 "September 2007" "User Manual"
+.TH fio 1 "October 2013" "User Manual"
.SH NAME
fio \- flexible I/O tester
.SH SYNOPSIS
.TP
.I float_list
List of floating numbers: A list of floating numbers, separated by
-a ':' charcater.
+a ':' character.
.SS "Parameter List"
.TP
.BI name \fR=\fPstr
Seed the random number generator in a predictable way so results are repeatable
across runs. Default: true.
.TP
+.BI randseed \fR=\fPint
+Seed the random number generators based on this seed value, to be able to
+control what sequence of output is being generated. If not set, the random
+sequence depends on the \fBrandrepeat\fR setting.
+.TP
.BI use_os_rand \fR=\fPbool
Fio can either use the random generator supplied by the OS to generator random
offsets, or it can use it's own internal generator (based on Tausworthe).
Do not pre-allocate space.
.TP
.B posix
-Pre-allocate via posix_fallocate().
+Pre-allocate via \fBposix_fallocate\fR\|(3).
.TP
.B keep
-Pre-allocate via fallocate() with FALLOC_FL_KEEP_SIZE set.
+Pre-allocate via \fBfallocate\fR\|(2) with FALLOC_FL_KEEP_SIZE set.
.TP
.B 0
Backward-compatible alias for 'none'.
.RE
.TP
.BI fadvise_hint \fR=\fPbool
-Use of \fIposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
+Use of \fBposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
are likely to be issued. Default: true.
.TP
.BI size \fR=\fPint
been transferred, unless limited by other options (\fBruntime\fR, for instance).
Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
divided between the available files for the job. If not set, fio will use the
-full size of the given files or devices. If the the files do not exist, size
+full size of the given files or devices. If the files do not exist, size
must be given. It is also possible to give size as a percentage between 1 and
100. If size=20% is given, fio will use 20% of the full size of the given files
or devices.
the remaining zeroed. With this set to some chunk size smaller than the block
size, fio can alternate random and zeroed data throughout the IO buffer.
.TP
+.BI buffer_pattern \fR=\fPstr
+If set, fio will fill the io buffers with this pattern. If not set, the contents
+of io buffers is defined by the other options related to buffer contents. The
+setting can be any pattern of bytes, and can be prefixed with 0x for hex
+values.
+.TP
.BI nrfiles \fR=\fPint
Number of files to use for this job. Default: 1.
.TP
.RS
.TP
.B sync
-Basic \fIread\fR\|(2) or \fIwrite\fR\|(2) I/O. \fIfseek\fR\|(2) is used to
+Basic \fBread\fR\|(2) or \fBwrite\fR\|(2) I/O. \fBfseek\fR\|(2) is used to
position the I/O location.
.TP
.B psync
-Basic \fIpread\fR\|(2) or \fIpwrite\fR\|(2) I/O.
+Basic \fBpread\fR\|(2) or \fBpwrite\fR\|(2) I/O.
.TP
.B vsync
-Basic \fIreadv\fR\|(2) or \fIwritev\fR\|(2) I/O. Will emulate queuing by
-coalescing adjacents IOs into a single submission.
+Basic \fBreadv\fR\|(2) or \fBwritev\fR\|(2) I/O. Will emulate queuing by
+coalescing adjacent IOs into a single submission.
.TP
.B pvsync
-Basic \fIpreadv\fR\|(2) or \fIpwritev\fR\|(2) I/O.
+Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
.TP
.B libaio
Linux native asynchronous I/O. This ioengine defines engine specific options.
.TP
.B posixaio
-POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
+POSIX asynchronous I/O using \fBaio_read\fR\|(3) and \fBaio_write\fR\|(3).
.TP
.B solarisaio
Solaris native asynchronous I/O.
Windows native asynchronous I/O.
.TP
.B mmap
-File is memory mapped with \fImmap\fR\|(2) and data copied using
-\fImemcpy\fR\|(3).
+File is memory mapped with \fBmmap\fR\|(2) and data copied using
+\fBmemcpy\fR\|(3).
.TP
.B splice
-\fIsplice\fR\|(2) is used to transfer the data and \fIvmsplice\fR\|(2) to
+\fBsplice\fR\|(2) is used to transfer the data and \fBvmsplice\fR\|(2) to
transfer data from user-space to the kernel.
.TP
.B syslet-rw
.TP
.B sg
SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
-the target is an sg character device, we use \fIread\fR\|(2) and
-\fIwrite\fR\|(2) for asynchronous I/O.
+the target is an sg character device, we use \fBread\fR\|(2) and
+\fBwrite\fR\|(2) for asynchronous I/O.
.TP
.B null
Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
This ioengine defines engine specific options.
.TP
.B netsplice
-Like \fBnet\fR, but uses \fIsplice\fR\|(2) and \fIvmsplice\fR\|(2) to map data
+Like \fBnet\fR, but uses \fBsplice\fR\|(2) and \fBvmsplice\fR\|(2) to map data
and send/receive. This ioengine defines engine specific options.
.TP
.B cpuio
.TP
.B guasi
The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
-approach to asycnronous I/O.
+approach to asynchronous I/O.
.br
See <http://www.xmailserver.org/guasi\-lib.html>.
.TP
`:\fIenginepath\fR'.
.TP
.B falloc
- IO engine that does regular linux native fallocate callt to simulate data
+ IO engine that does regular linux native fallocate call to simulate data
transfer as fio ioengine
.br
DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
.BI direct \fR=\fPbool
If true, use non-buffered I/O (usually O_DIRECT). Default: false.
.TP
+.BI atomic \fR=\fPbool
+If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
+to be stable once acknowledged by the operating system. Only Linux supports
+O_ATOMIC right now.
+.TP
.BI buffered \fR=\fPbool
If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
Default: true.
Make every Nth write a barrier write.
.TP
.BI sync_file_range \fR=\fPstr:int
-Use sync_file_range() for every \fRval\fP number of write operations. Fio will
-track range of writes that have happened since the last sync_file_range() call.
+Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
+track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
\fRstr\fP can currently be one or more of:
.RS
.TP
.P
So if you do sync_file_range=wait_before,write:8, fio would use
\fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
-Also see the sync_file_range(2) man page. This option is Linux specific.
+Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
.TP
.BI overwrite \fR=\fPbool
If writing, setup the file first and do overwrites. Default: false.
workload, fio may read or write some blocks multiple times.
.TP
.BI nice \fR=\fPint
-Run job with given nice value. See \fInice\fR\|(2).
+Run job with given nice value. See \fBnice\fR\|(2).
.TP
.BI prio \fR=\fPint
Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
-\fIionice\fR\|(1).
+\fBionice\fR\|(1).
.TP
.BI prioclass \fR=\fPint
-Set I/O priority class. See \fIionice\fR\|(1).
+Set I/O priority class. See \fBionice\fR\|(1).
.TP
.BI thinktime \fR=\fPint
Stall job for given number of microseconds between issuing I/Os.
Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
milliseconds. Default: 1000ms.
.TP
+.BI latency_target \fR=\fPint
+If set, fio will attempt to find the max performance point that the given
+workload will run at while maintaining a latency below this target. The
+values is given in microseconds. See \fBlatency_window\fR and
+\fBlatency_percentile\fR.
+.TP
+.BI latency_window \fR=\fPint
+Used with \fBlatency_target\fR to specify the sample window that the job
+is run at varying queue depths to test the performance. The value is given
+in microseconds.
+.TP
+.BI latency_percentile \fR=\fPfloat
+The percentage of IOs that must fall within the criteria specified by
+\fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
+to 100.0, meaning that all IOs must be equal or below to the value set
+by \fBlatency_target\fR.
+.TP
.BI max_latency \fR=\fPint
If set, fio will exit the job if it exceeds this maximum latency. It will exit
with an ETIME error.
Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
.TP
.BI numa_cpu_nodes \fR=\fPstr
-Set this job running on spcified NUMA nodes' CPUs. The arguments allow
+Set this job running on specified NUMA nodes' CPUs. The arguments allow
comma delimited list of cpu numbers, A-B ranges, or 'all'.
.TP
.BI numa_mem_policy \fR=\fPstr
Set this job's memory policy and corresponding NUMA nodes. Format of
-the argements:
+the arguments:
.RS
.TP
.B <mode>[:<nodelist>]
.RS
.TP
.B malloc
-Allocate memory with \fImalloc\fR\|(3).
+Allocate memory with \fBmalloc\fR\|(3).
.TP
.B shm
-Use shared memory buffers allocated through \fIshmget\fR\|(2).
+Use shared memory buffers allocated through \fBshmget\fR\|(2).
.TP
.B shmhuge
Same as \fBshm\fR, but use huge pages as backing.
.TP
.B mmap
-Use \fImmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
+Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
is given after the option in the format `:\fIfile\fR'.
.TP
.B mmaphuge
.RE
.TP
.BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
-This indiciates the memory alignment of the IO memory buffers. Note that the
+This indicates the memory alignment of the IO memory buffers. Note that the
given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
the alignment of the following buffers are given by the \fBbs\fR used. In
other words, if using a \fBbs\fR that is a multiple of the page sized in the
If true, serialize file creation for the jobs. Default: true.
.TP
.BI create_fsync \fR=\fPbool
-\fIfsync\fR\|(2) data file after creation. Default: true.
+\fBfsync\fR\|(2) data file after creation. Default: true.
.TP
.BI create_on_open \fR=\fPbool
If true, the files are not created until they are opened for IO by the job.
If given, write a bandwidth log of the jobs in this job file. Can be used to
store data of the bandwidth of the jobs in their lifetime. The included
fio_generate_plots script uses gnuplot to turn these text files into nice
-graphs. See \fBwrite_log_log\fR for behaviour of given filename. For this
+graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
option, the postfix is _bw.log.
.TP
.BI write_lat_log \fR=\fPstr
.TP
.BI disable_lat \fR=\fPbool
Disable measurements of total latency numbers. Useful only for cutting
-back the number of calls to gettimeofday, as that does impact performance at
+back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
really high IOPS rates. Note that to really get rid of a large amount of these
calls, this option must be used with disable_slat and disable_bw as well.
.TP
.RS
.TP
.B gettimeofday
-gettimeofday(2)
+\fBgettimeofday\fR\|(2)
.TP
.B clock_gettime
-clock_gettime(2)
+\fBclock_gettime\fR\|(2)
.TP
.B cpu
Internal CPU clock source
means supporting TSC Invariant.
.TP
.BI gtod_reduce \fR=\fPbool
-Enable all of the gettimeofday() reducing options (disable_clat, disable_slat,
+Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
disable_bw) plus reduce precision of the timeout somewhat to really shrink the
-gettimeofday() call count. With this option enabled, we only do about 0.4% of
+\fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
the gtod() calls we would have done if all time keeping was enabled.
.TP
.BI gtod_cpu \fR=\fPint
Sometimes it's cheaper to dedicate a single thread of execution to just getting
the current time. Fio (and databases, for instance) are very intensive on
-gettimeofday() calls. With this option, you can set one CPU aside for doing
+\fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
nothing but logging current time to a shared memory location. Then the other
threads/processes that run IO workloads need only copy that segment, instead of
-entering the kernel with a gettimeofday() call. The CPU set aside for doing
+entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
these time calls will be excluded from other uses. Fio will manually clear it
from the CPU mask of other jobs.
.TP
hostname must be omitted if this option is used.
.TP
.BI (net, pingpong) \fR=\fPbool
-Normaly a network writer will just continue writing data, and a network reader
+Normally a network writer will just continue writing data, and a network reader
will just consume packages. If pingpong=1 is set, a writer will send its normal
payload to the reader, then wait for the reader to send the same payload back.
This allows fio to measure network latencies. The submission and completion
Preallocate donor's file on init
.TP
.BI 1:
-allocate space immidietly inside defragment event, and free right after event
+allocate space immediately inside defragment event, and free right after event
.RE
-.TP
.SH OUTPUT
While running, \fBfio\fR will display the status of the created jobs. For
example:
projects / fio.git / blobdiff