4 fio is a tool that will spawn a number of threads or processes doing a
5 particular type of io action as specified by the user. fio takes a
6 number of global parameters, each inherited by the thread unless
7 otherwise parameters given to them overriding that setting is given.
8 The typical use of fio is to write a job file matching the io load
15 fio resides in a git repo, the canonical place is:
17 git://brick.kernel.dk/data/git/fio.git
19 Snapshots are frequently generated and they include the git meta data as
20 well. You can download them here:
22 http://brick.kernel.dk/snaps/
24 Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository, you
27 http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
33 There's a mailing list associated with fio. It's meant for general
34 discussion, bug reporting, questions - basically anything that has to
35 do with fio. An automated mail detailing recent commits is automatically
36 sent to the list at most daily. The list address is fio-devel@kernel.dk,
37 subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
43 Just type 'make' and 'make install'. If on FreeBSD, for now you have to
44 specify the FreeBSD Makefile with -f, eg:
46 $ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
48 Likewise with OpenSolaris, use the Makefile.solaris to compile there.
49 This might change in the future if I opt for an autoconf type setup.
56 --output Write output to file
57 --timeout Runtime in seconds
58 --latency-log Generate per-job latency logs
59 --bandwidth-log Generate per-job bandwidth logs
60 --minimal Minimal (terse) output
61 --version Print version info and exit
63 Any parameters following the options will be assumed to be job files,
64 unless they match a job file parameter. You can add as many as you want,
65 each job file will be regarded as a separate group and fio will stonewall
72 See the HOWTO file for a more detailed description of parameters and what
73 they mean. This file contains the terse version. Only a few options can
74 be controlled with command line parameters, generally it's a lot easier to
75 just write a simple job file to describe the workload. The job file format
76 is in the ini style format, as it's easy to read and write for the user.
78 The job file parameters are:
80 name=x Use 'x' as the identifier for this job.
81 directory=x Use 'x' as the top level directory for storing files
82 filename=x Force the use of 'x' as the filename for all files
83 in this thread. If not given, fio will make up
84 a suitable filename based on the thread and file
86 rw=x 'x' may be: read, randread, write, randwrite,
87 rw (read-write mix), randrw (read-write random mix)
88 rwmixcycle=x Base cycle for switching between read and write
90 rwmixread=x 'x' percentage of rw mix ios will be reads. If
91 rwmixwrite is also given, the last of the two will
92 be used if they don't add up to 100%.
93 rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
95 rand_repeatable=x The sequence of random io blocks can be repeatable
96 across runs, if 'x' is 1.
97 size=x Set file size to x bytes (x string can include k/m/g)
98 ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
99 posixaio for POSIX aio, sync for regular read/write io,
100 mmap for mmap'ed io, splice for using splice/vmsplice,
101 or sgio for direct SG_IO io. The latter only works on
102 Linux on SCSI (or SCSI-like devices, such as
103 usb-storage or sata/libata driven) devices. Fio also
104 has a null io engine, which is mainly used for testing
106 iodepth=x For async io, allow 'x' ios in flight
107 overwrite=x If 'x', layout a write file first.
108 nrfiles=x Spread io load over 'x' number of files per job,
110 prio=x Run io at prio X, 0-7 is the kernel allowed range
111 prioclass=x Run io at prio class X
112 bs=x Use 'x' for thread blocksize. May include k/m postfix.
113 bsrange=x-y Mix thread block sizes randomly between x and y. May
114 also include k/m postfix.
115 direct=x 1 for direct IO, 0 for buffered IO
116 thinktime=x "Think" x usec after each io
117 rate=x Throttle rate to x KiB/sec
118 ratemin=x Quit if rate of x KiB/sec can't be met
119 ratecycle=x ratemin averaged over x msecs
120 cpumask=x Only allow job to run on CPUs defined by mask.
121 fsync=x If writing with buffered IO, fsync after every
122 'x' blocks have been written.
123 end_fsync=x If 'x', run fsync() after end-of-job.
124 startdelay=x Start this thread x seconds after startup
125 timeout=x Terminate x seconds after startup. Can include a
126 normal time suffix if not given in seconds, such as
127 'm' for minutes, 'h' for hours, and 'd' for days.
128 offset=x Start io at offset x (x string can include k/m/g)
129 invalidate=x Invalidate page cache for file prior to doing io
130 sync=x Use sync writes if x and writing buffered IO.
131 mem=x If x == malloc, use malloc for buffers. If x == shm,
132 use shared memory for buffers. If x == mmap, use
134 exitall When one thread quits, terminate the others
135 bwavgtime=x Average bandwidth stats over an x msec window.
136 create_serialize=x If 'x', serialize file creation.
137 create_fsync=x If 'x', run fsync() after file creation.
138 unlink If set, unlink files when done.
139 loops=x Run the job 'x' number of times.
140 verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
141 use crc32 for verifies. md5 is 'safer', but crc32 is
142 a lot faster. Only makes sense for writing to a file.
143 stonewall Wait for preceeding jobs to end before running.
144 numjobs=x Create 'x' similar entries for this job
145 thread Use pthreads instead of forked jobs
147 zoneskip=y Zone options must be paired. If given, the job
148 will skip y bytes for every x read/written. This
149 can be used to gauge hard drive speed over the entire
150 platter, without reading everything. Both x/y can
151 include k/m/g suffix.
152 iolog=x Open and read io pattern from file 'x'. The file must
153 contain one io action per line in the following format:
155 where with rw=0/1 for read/write, and the offset
156 and length entries being in bytes.
157 write_iolog=x Write an iolog to file 'x' in the same format as iolog.
158 The iolog options are exclusive, if both given the
159 read iolog will be performed.
160 write_bw_log Write a bandwidth log.
161 write_lat_log Write a latency log.
162 lockmem=x Lock down x amount of memory on the machine, to
163 simulate a machine with less memory available. x can
164 include k/m/g suffix.
165 nice=x Run job at given nice value.
166 exec_prerun=x Run 'x' before job io is begun.
167 exec_postrun=x Run 'x' after job io has finished.
168 ioscheduler=x Use ioscheduler 'x' for this job.
169 cpuload=x For a CPU io thread, percentage of CPU time to attempt
171 cpuchunks=x Split burn cycles into pieces of x.
177 Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
178 of the Linux IO subsystem and schedulers. He got tired of writing
179 specific test applications to simulate a given workload, and found that
180 the existing io benchmark/test tools out there weren't flexible enough
181 to do what he wanted.
183 Jens Axboe <axboe@kernel.dk> 20060905