mutex error handling
[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
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68
69Any parameters following the options will be assumed to be job files,
70unless they match a job file parameter. You can add as many as you want,
71each job file will be regarded as a separate group and fio will stonewall
72its execution.
972cfd25 73
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74
75Job file
76--------
77
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78See the HOWTO file for a more detailed description of parameters and what
79they mean. This file contains the terse version. Only a few options can
80be controlled with command line parameters, generally it's a lot easier to
81just write a simple job file to describe the workload. The job file format
82is in the ini style format, as it's easy to read and write for the user.
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83
84The job file parameters are:
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01452055 86 name=x Use 'x' as the identifier for this job.
61697c37 87 description=x 'x' is a text description of the job.
ebac4655 88 directory=x Use 'x' as the top level directory for storing files
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89 filename=x Force the use of 'x' as the filename for all files
90 in this thread. If not given, fio will make up
91 a suitable filename based on the thread and file
92 number.
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93 rw=x 'x' may be: read, randread, write, randwrite,
94 rw (read-write mix), randrw (read-write random mix)
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95 rwmixcycle=x Base cycle for switching between read and write
96 in msecs.
97 rwmixread=x 'x' percentage of rw mix ios will be reads. If
98 rwmixwrite is also given, the last of the two will
99 be used if they don't add up to 100%.
100 rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
101 rwmixread.
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102 rand_repeatable=x The sequence of random io blocks can be repeatable
103 across runs, if 'x' is 1.
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104 size=x Set file size to x bytes (x string can include k/m/g)
105 ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
106 posixaio for POSIX aio, sync for regular read/write io,
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107 mmap for mmap'ed io, syslet-rw for syslet driven
108 read/write, splice for using splice/vmsplice,
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109 sgio for direct SG_IO io, or net for network io. sgio
110 only works on Linux on SCSI (or SCSI-like devices,
111 such as usb-storage or sata/libata driven) devices.
112 Fio also has a null io engine, which is mainly used
113 for testing fio itself.
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114 iodepth=x For async io, allow 'x' ios in flight
115 overwrite=x If 'x', layout a write file first.
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116 nrfiles=x Spread io load over 'x' number of files per job,
117 if possible.
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118 prio=x Run io at prio X, 0-7 is the kernel allowed range
119 prioclass=x Run io at prio class X
120 bs=x Use 'x' for thread blocksize. May include k/m postfix.
121 bsrange=x-y Mix thread block sizes randomly between x and y. May
122 also include k/m postfix.
123 direct=x 1 for direct IO, 0 for buffered IO
124 thinktime=x "Think" x usec after each io
125 rate=x Throttle rate to x KiB/sec
126 ratemin=x Quit if rate of x KiB/sec can't be met
127 ratecycle=x ratemin averaged over x msecs
128 cpumask=x Only allow job to run on CPUs defined by mask.
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129 fsync=x If writing with buffered IO, fsync after every
130 'x' blocks have been written.
131 end_fsync=x If 'x', run fsync() after end-of-job.
ebac4655 132 startdelay=x Start this thread x seconds after startup
03b74b3e 133 runtime=x Terminate x seconds after startup. Can include a
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134 normal time suffix if not given in seconds, such as
135 'm' for minutes, 'h' for hours, and 'd' for days.
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136 offset=x Start io at offset x (x string can include k/m/g)
137 invalidate=x Invalidate page cache for file prior to doing io
795407ca 138 sync=x Use sync writes if x and writing buffered IO.
ebac4655 139 mem=x If x == malloc, use malloc for buffers. If x == shm,
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140 use shared memory for buffers. If x == mmap, use
141 anonymous mmap.
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142 exitall When one thread quits, terminate the others
143 bwavgtime=x Average bandwidth stats over an x msec window.
144 create_serialize=x If 'x', serialize file creation.
145 create_fsync=x If 'x', run fsync() after file creation.
f6cbb269 146 unlink If set, unlink files when done.
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147 loops=x Run the job 'x' number of times.
148 verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
149 use crc32 for verifies. md5 is 'safer', but crc32 is
150 a lot faster. Only makes sense for writing to a file.
151 stonewall Wait for preceeding jobs to end before running.
152 numjobs=x Create 'x' similar entries for this job
153 thread Use pthreads instead of forked jobs
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154 zonesize=x
155 zoneskip=y Zone options must be paired. If given, the job
156 will skip y bytes for every x read/written. This
157 can be used to gauge hard drive speed over the entire
158 platter, without reading everything. Both x/y can
159 include k/m/g suffix.
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160 iolog=x Open and read io pattern from file 'x'. The file must
161 contain one io action per line in the following format:
162 rw, offset, length
163 where with rw=0/1 for read/write, and the offset
164 and length entries being in bytes.
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165 write_iolog=x Write an iolog to file 'x' in the same format as iolog.
166 The iolog options are exclusive, if both given the
167 read iolog will be performed.
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168 write_bw_log Write a bandwidth log.
169 write_lat_log Write a latency log.
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170 lockmem=x Lock down x amount of memory on the machine, to
171 simulate a machine with less memory available. x can
172 include k/m/g suffix.
b6f4d880 173 nice=x Run job at given nice value.
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174 exec_prerun=x Run 'x' before job io is begun.
175 exec_postrun=x Run 'x' after job io has finished.
da86774e 176 ioscheduler=x Use ioscheduler 'x' for this job.
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177 cpuload=x For a CPU io thread, percentage of CPU time to attempt
178 to burn.
179 cpuchunks=x Split burn cycles into pieces of x.
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182Author
183------
184
aae22ca7 185Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
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186of the Linux IO subsystem and schedulers. He got tired of writing
187specific test applications to simulate a given workload, and found that
188the existing io benchmark/test tools out there weren't flexible enough
189to do what he wanted.
190
aae22ca7 191Jens Axboe <axboe@kernel.dk> 20060905
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