Fix bug with stonewall option causing segfault
[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
17git://brick.kernel.dk/data/git/fio.git
18
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19Snapshots are frequently generated and they include the git meta data as
20well. You can download them here:
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21
22http://brick.kernel.dk/snaps/
23
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24Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository for
25SUSE variants, you can find them here:
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26
27http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
28
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29Dag Wieƫrs has RPMs for Red Hat related distros, find them here:
30
31http://dag.wieers.com/rpm/packages/fio/
32
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34Mailing list
35------------
36
37There's a mailing list associated with fio. It's meant for general
38discussion, bug reporting, questions - basically anything that has to
39do with fio. An automated mail detailing recent commits is automatically
40sent to the list at most daily. The list address is fio-devel@kernel.dk,
41subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
42
43
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44Building
45--------
46
47Just type 'make' and 'make install'. If on FreeBSD, for now you have to
48specify the FreeBSD Makefile with -f, eg:
49
50$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
51
edffcb96 52Likewise with OpenSolaris, use the Makefile.solaris to compile there.
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53This might change in the future if I opt for an autoconf type setup.
54
55
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56Command line
57------------
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58
59$ fio
b4692828 60 --output Write output to file
03b74b3e 61 --runtime Runtime in seconds
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62 --latency-log Generate per-job latency logs
63 --bandwidth-log Generate per-job bandwidth logs
64 --minimal Minimal (terse) output
65 --version Print version info and exit
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66 --help Print this page
67 --cmdhelp=cmd Print command help, "all" for all of them
cca73aa7 68 --showcmd Turn a job file into command line options
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69
70Any parameters following the options will be assumed to be job files,
71unless they match a job file parameter. You can add as many as you want,
72each job file will be regarded as a separate group and fio will stonewall
73its execution.
972cfd25 74
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75
76Job file
77--------
78
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79See the HOWTO file for a more detailed description of parameters and what
80they mean. This file contains the terse version. Only a few options can
81be controlled with command line parameters, generally it's a lot easier to
82just write a simple job file to describe the workload. The job file format
83is in the ini style format, as it's easy to read and write for the user.
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84
85The job file parameters are:
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01452055 87 name=x Use 'x' as the identifier for this job.
61697c37 88 description=x 'x' is a text description of the job.
ebac4655 89 directory=x Use 'x' as the top level directory for storing files
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90 filename=x Force the use of 'x' as the filename for all files
91 in this thread. If not given, fio will make up
92 a suitable filename based on the thread and file
93 number.
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94 rw=x 'x' may be: read, randread, write, randwrite,
95 rw (read-write mix), randrw (read-write random mix)
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96 rwmixcycle=x Base cycle for switching between read and write
97 in msecs.
98 rwmixread=x 'x' percentage of rw mix ios will be reads. If
99 rwmixwrite is also given, the last of the two will
100 be used if they don't add up to 100%.
101 rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
102 rwmixread.
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103 rand_repeatable=x The sequence of random io blocks can be repeatable
104 across runs, if 'x' is 1.
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105 size=x Set file size to x bytes (x string can include k/m/g)
106 ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
107 posixaio for POSIX aio, sync for regular read/write io,
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108 mmap for mmap'ed io, syslet-rw for syslet driven
109 read/write, splice for using splice/vmsplice,
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110 sgio for direct SG_IO io, net for network io, or cpuio
111 for a cycler burner load. sgio only works on Linux on
112 SCSI (or SCSI-like devices, such as usb-storage or
113 sata/libata driven) devices. Fio also has a null io
114 engine, which is mainly used for testing fio itself.
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115 iodepth=x For async io, allow 'x' ios in flight
116 overwrite=x If 'x', layout a write file first.
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117 nrfiles=x Spread io load over 'x' number of files per job,
118 if possible.
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119 prio=x Run io at prio X, 0-7 is the kernel allowed range
120 prioclass=x Run io at prio class X
121 bs=x Use 'x' for thread blocksize. May include k/m postfix.
122 bsrange=x-y Mix thread block sizes randomly between x and y. May
123 also include k/m postfix.
124 direct=x 1 for direct IO, 0 for buffered IO
125 thinktime=x "Think" x usec after each io
126 rate=x Throttle rate to x KiB/sec
127 ratemin=x Quit if rate of x KiB/sec can't be met
128 ratecycle=x ratemin averaged over x msecs
129 cpumask=x Only allow job to run on CPUs defined by mask.
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130 fsync=x If writing with buffered IO, fsync after every
131 'x' blocks have been written.
132 end_fsync=x If 'x', run fsync() after end-of-job.
ebac4655 133 startdelay=x Start this thread x seconds after startup
03b74b3e 134 runtime=x Terminate x seconds after startup. Can include a
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135 normal time suffix if not given in seconds, such as
136 'm' for minutes, 'h' for hours, and 'd' for days.
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137 offset=x Start io at offset x (x string can include k/m/g)
138 invalidate=x Invalidate page cache for file prior to doing io
795407ca 139 sync=x Use sync writes if x and writing buffered IO.
ebac4655 140 mem=x If x == malloc, use malloc for buffers. If x == shm,
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141 use shared memory for buffers. If x == mmap, use
142 anonymous mmap.
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143 exitall When one thread quits, terminate the others
144 bwavgtime=x Average bandwidth stats over an x msec window.
145 create_serialize=x If 'x', serialize file creation.
146 create_fsync=x If 'x', run fsync() after file creation.
f6cbb269 147 unlink If set, unlink files when done.
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148 loops=x Run the job 'x' number of times.
149 verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
150 use crc32 for verifies. md5 is 'safer', but crc32 is
151 a lot faster. Only makes sense for writing to a file.
152 stonewall Wait for preceeding jobs to end before running.
153 numjobs=x Create 'x' similar entries for this job
154 thread Use pthreads instead of forked jobs
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155 zonesize=x
156 zoneskip=y Zone options must be paired. If given, the job
157 will skip y bytes for every x read/written. This
158 can be used to gauge hard drive speed over the entire
159 platter, without reading everything. Both x/y can
160 include k/m/g suffix.
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161 iolog=x Open and read io pattern from file 'x'. The file must
162 contain one io action per line in the following format:
163 rw, offset, length
164 where with rw=0/1 for read/write, and the offset
165 and length entries being in bytes.
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166 write_iolog=x Write an iolog to file 'x' in the same format as iolog.
167 The iolog options are exclusive, if both given the
168 read iolog will be performed.
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169 write_bw_log Write a bandwidth log.
170 write_lat_log Write a latency log.
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171 lockmem=x Lock down x amount of memory on the machine, to
172 simulate a machine with less memory available. x can
173 include k/m/g suffix.
b6f4d880 174 nice=x Run job at given nice value.
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175 exec_prerun=x Run 'x' before job io is begun.
176 exec_postrun=x Run 'x' after job io has finished.
da86774e 177 ioscheduler=x Use ioscheduler 'x' for this job.
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178 cpuload=x For a CPU io thread, percentage of CPU time to attempt
179 to burn.
ba0fbe10 180 cpuchunks=x Split burn cycles into pieces of x usecs.
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183Author
184------
185
aae22ca7 186Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
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187of the Linux IO subsystem and schedulers. He got tired of writing
188specific test applications to simulate a given workload, and found that
189the existing io benchmark/test tools out there weren't flexible enough
190to do what he wanted.
191
aae22ca7 192Jens Axboe <axboe@kernel.dk> 20060905
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