fio: build warning fix on gcc-3.4.6-3
[fio.git] / README
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1fio
2---
3
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4fio is a tool that will spawn a number of threads or processes doing a
5particular type of io action as specified by the user. fio takes a
6number of global parameters, each inherited by the thread unless
7otherwise parameters given to them overriding that setting is given.
8The typical use of fio is to write a job file matching the io load
9one wants to simulate.
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11
12Source
13------
14
15fio resides in a git repo, the canonical place is:
16
6b3eccb1 17git://git.kernel.dk/fio.git
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18
19The http protocol also works, path is the same.
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21Snapshots are frequently generated and they include the git meta data as
22well. You can download them here:
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23
24http://brick.kernel.dk/snaps/
25
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26Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository for
27SUSE variants, you can find them here:
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28
29http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
30
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31Dag Wieƫrs has RPMs for Red Hat related distros, find them here:
32
33http://dag.wieers.com/rpm/packages/fio/
34
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35Mandriva has integrated fio into their package repository, so installing
36on that distro should be as easy as typing 'urpmi fio'.
37
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39Mailing list
40------------
41
42There's a mailing list associated with fio. It's meant for general
43discussion, bug reporting, questions - basically anything that has to
44do with fio. An automated mail detailing recent commits is automatically
45sent to the list at most daily. The list address is fio-devel@kernel.dk,
46subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
47
48
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49Building
50--------
51
52Just type 'make' and 'make install'. If on FreeBSD, for now you have to
53specify the FreeBSD Makefile with -f, eg:
54
55$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
56
edffcb96 57Likewise with OpenSolaris, use the Makefile.solaris to compile there.
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58This might change in the future if I opt for an autoconf type setup.
59
60
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61Command line
62------------
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63
64$ fio
b4692828 65 --output Write output to file
03b74b3e 66 --runtime Runtime in seconds
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67 --latency-log Generate per-job latency logs
68 --bandwidth-log Generate per-job bandwidth logs
69 --minimal Minimal (terse) output
70 --version Print version info and exit
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71 --help Print this page
72 --cmdhelp=cmd Print command help, "all" for all of them
cca73aa7 73 --showcmd Turn a job file into command line options
724e4435 74 --readonly Turn on safety read-only checks
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75 --eta=when When ETA estimate should be printed
76 May be "always", "never" or "auto"
77
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78
79Any parameters following the options will be assumed to be job files,
80unless they match a job file parameter. You can add as many as you want,
81each job file will be regarded as a separate group and fio will stonewall
82its execution.
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84The --readonly switch is an extra safety guard to prevent accidentically
85turning on a write setting when that is not desired. Fio will only write
86if rw=write/randwrite/rw/randrw is given, but this extra safety net can
87be used as an extra precaution. It will also enable a write check in the
88io engine core to prevent an accidental write due to a fio bug.
89
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90
91Job file
92--------
93
71bfa161 94See the HOWTO file for a more detailed description of parameters and what
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95they mean. This file contains the terse version. You can describe big and
96complex setups with the command line, but generally it's a lot easier to
71bfa161 97just write a simple job file to describe the workload. The job file format
4661f3d0 98is in the ini style format, as that is easy to read and write for the user.
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99
100The job file parameters are:
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01452055 102 name=x Use 'x' as the identifier for this job.
61697c37 103 description=x 'x' is a text description of the job.
ebac4655 104 directory=x Use 'x' as the top level directory for storing files
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105 filename=x Force the use of 'x' as the filename for all files
106 in this thread. If not given, fio will make up
107 a suitable filename based on the thread and file
108 number.
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109 rw=x 'x' may be: read, randread, write, randwrite,
110 rw (read-write mix), randrw (read-write random mix)
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111 rwmixcycle=x Base cycle for switching between read and write
112 in msecs.
113 rwmixread=x 'x' percentage of rw mix ios will be reads. If
114 rwmixwrite is also given, the last of the two will
115 be used if they don't add up to 100%.
116 rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
117 rwmixread.
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118 rand_repeatable=x The sequence of random io blocks can be repeatable
119 across runs, if 'x' is 1.
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120 size=x Set file size to x bytes (x string can include k/m/g)
121 ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
122 posixaio for POSIX aio, sync for regular read/write io,
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123 mmap for mmap'ed io, syslet-rw for syslet driven
124 read/write, splice for using splice/vmsplice,
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125 sgio for direct SG_IO io, net for network io, or cpuio
126 for a cycler burner load. sgio only works on Linux on
127 SCSI (or SCSI-like devices, such as usb-storage or
128 sata/libata driven) devices. Fio also has a null io
129 engine, which is mainly used for testing fio itself.
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130 iodepth=x For async io, allow 'x' ios in flight
131 overwrite=x If 'x', layout a write file first.
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132 nrfiles=x Spread io load over 'x' number of files per job,
133 if possible.
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134 prio=x Run io at prio X, 0-7 is the kernel allowed range
135 prioclass=x Run io at prio class X
136 bs=x Use 'x' for thread blocksize. May include k/m postfix.
137 bsrange=x-y Mix thread block sizes randomly between x and y. May
138 also include k/m postfix.
139 direct=x 1 for direct IO, 0 for buffered IO
140 thinktime=x "Think" x usec after each io
141 rate=x Throttle rate to x KiB/sec
142 ratemin=x Quit if rate of x KiB/sec can't be met
143 ratecycle=x ratemin averaged over x msecs
144 cpumask=x Only allow job to run on CPUs defined by mask.
d2e268b0 145 cpus_allowed=x Like 'cpumask', but allow text setting of CPU affinity.
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146 fsync=x If writing with buffered IO, fsync after every
147 'x' blocks have been written.
148 end_fsync=x If 'x', run fsync() after end-of-job.
ebac4655 149 startdelay=x Start this thread x seconds after startup
03b74b3e 150 runtime=x Terminate x seconds after startup. Can include a
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151 normal time suffix if not given in seconds, such as
152 'm' for minutes, 'h' for hours, and 'd' for days.
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153 offset=x Start io at offset x (x string can include k/m/g)
154 invalidate=x Invalidate page cache for file prior to doing io
795407ca 155 sync=x Use sync writes if x and writing buffered IO.
ebac4655 156 mem=x If x == malloc, use malloc for buffers. If x == shm,
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157 use shared memory for buffers. If x == mmap, use
158 anonymous mmap.
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159 exitall When one thread quits, terminate the others
160 bwavgtime=x Average bandwidth stats over an x msec window.
161 create_serialize=x If 'x', serialize file creation.
162 create_fsync=x If 'x', run fsync() after file creation.
f6cbb269 163 unlink If set, unlink files when done.
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164 loops=x Run the job 'x' number of times.
165 verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
166 use crc32 for verifies. md5 is 'safer', but crc32 is
167 a lot faster. Only makes sense for writing to a file.
168 stonewall Wait for preceeding jobs to end before running.
169 numjobs=x Create 'x' similar entries for this job
170 thread Use pthreads instead of forked jobs
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171 zonesize=x
172 zoneskip=y Zone options must be paired. If given, the job
173 will skip y bytes for every x read/written. This
174 can be used to gauge hard drive speed over the entire
175 platter, without reading everything. Both x/y can
176 include k/m/g suffix.
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177 iolog=x Open and read io pattern from file 'x'. The file must
178 contain one io action per line in the following format:
179 rw, offset, length
180 where with rw=0/1 for read/write, and the offset
181 and length entries being in bytes.
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182 write_iolog=x Write an iolog to file 'x' in the same format as iolog.
183 The iolog options are exclusive, if both given the
184 read iolog will be performed.
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185 write_bw_log Write a bandwidth log.
186 write_lat_log Write a latency log.
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187 lockmem=x Lock down x amount of memory on the machine, to
188 simulate a machine with less memory available. x can
189 include k/m/g suffix.
b6f4d880 190 nice=x Run job at given nice value.
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191 exec_prerun=x Run 'x' before job io is begun.
192 exec_postrun=x Run 'x' after job io has finished.
da86774e 193 ioscheduler=x Use ioscheduler 'x' for this job.
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194 cpuload=x For a CPU io thread, percentage of CPU time to attempt
195 to burn.
ba0fbe10 196 cpuchunks=x Split burn cycles into pieces of x usecs.
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199Author
200------
201
aae22ca7 202Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
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203of the Linux IO subsystem and schedulers. He got tired of writing
204specific test applications to simulate a given workload, and found that
205the existing io benchmark/test tools out there weren't flexible enough
206to do what he wanted.
207
aae22ca7 208Jens Axboe <axboe@kernel.dk> 20060905
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