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fio
---
fio is a tool that will spawn a number of threads or processes doing a
particular type of io action as specified by the user. fio takes a
number of global parameters, each inherited by the thread unless
otherwise parameters given to them overriding that setting is given.
The typical use of fio is to write a job file matching the io load
one wants to simulate.
Source
------
fio resides in a git repo, the canonical place is:
git://brick.kernel.dk/data/git/fio.git
Snapshots are frequently generated and they include the git meta data as
well. You can download them here:
http://brick.kernel.dk/snaps/
Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository, you
can find them here:
http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
Mailing list
------------
There's a mailing list associated with fio. It's meant for general
discussion, bug reporting, questions - basically anything that has to
do with fio. An automated mail detailing recent commits is automatically
sent to the list at most daily. The list address is fio-devel@kernel.dk,
subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
Building
--------
Just type 'make' and 'make install'. If on FreeBSD, for now you have to
specify the FreeBSD Makefile with -f, eg:
$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
Likewise with OpenSolaris, use the Makefile.solaris to compile there.
This might change in the future if I opt for an autoconf type setup.
Command line
------------
$ fio
--output Write output to file
--runtime Runtime in seconds
--latency-log Generate per-job latency logs
--bandwidth-log Generate per-job bandwidth logs
--minimal Minimal (terse) output
--version Print version info and exit
--help Print this page
--cmdhelp=cmd Print command help, "all" for all of them
Any parameters following the options will be assumed to be job files,
unless they match a job file parameter. You can add as many as you want,
each job file will be regarded as a separate group and fio will stonewall
its execution.
Job file
--------
See the HOWTO file for a more detailed description of parameters and what
they mean. This file contains the terse version. Only a few options can
be controlled with command line parameters, generally it's a lot easier to
just write a simple job file to describe the workload. The job file format
is in the ini style format, as it's easy to read and write for the user.
The job file parameters are:
name=x Use 'x' as the identifier for this job.
directory=x Use 'x' as the top level directory for storing files
filename=x Force the use of 'x' as the filename for all files
in this thread. If not given, fio will make up
a suitable filename based on the thread and file
number.
rw=x 'x' may be: read, randread, write, randwrite,
rw (read-write mix), randrw (read-write random mix)
rwmixcycle=x Base cycle for switching between read and write
in msecs.
rwmixread=x 'x' percentage of rw mix ios will be reads. If
rwmixwrite is also given, the last of the two will
be used if they don't add up to 100%.
rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
rwmixread.
rand_repeatable=x The sequence of random io blocks can be repeatable
across runs, if 'x' is 1.
size=x Set file size to x bytes (x string can include k/m/g)
ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
posixaio for POSIX aio, sync for regular read/write io,
mmap for mmap'ed io, splice for using splice/vmsplice,
or sgio for direct SG_IO io. The latter only works on
Linux on SCSI (or SCSI-like devices, such as
usb-storage or sata/libata driven) devices. Fio also
has a null io engine, which is mainly used for testing
fio itself.
iodepth=x For async io, allow 'x' ios in flight
overwrite=x If 'x', layout a write file first.
nrfiles=x Spread io load over 'x' number of files per job,
if possible.
prio=x Run io at prio X, 0-7 is the kernel allowed range
prioclass=x Run io at prio class X
bs=x Use 'x' for thread blocksize. May include k/m postfix.
bsrange=x-y Mix thread block sizes randomly between x and y. May
also include k/m postfix.
direct=x 1 for direct IO, 0 for buffered IO
thinktime=x "Think" x usec after each io
rate=x Throttle rate to x KiB/sec
ratemin=x Quit if rate of x KiB/sec can't be met
ratecycle=x ratemin averaged over x msecs
cpumask=x Only allow job to run on CPUs defined by mask.
fsync=x If writing with buffered IO, fsync after every
'x' blocks have been written.
end_fsync=x If 'x', run fsync() after end-of-job.
startdelay=x Start this thread x seconds after startup
runtime=x Terminate x seconds after startup. Can include a
normal time suffix if not given in seconds, such as
'm' for minutes, 'h' for hours, and 'd' for days.
offset=x Start io at offset x (x string can include k/m/g)
invalidate=x Invalidate page cache for file prior to doing io
sync=x Use sync writes if x and writing buffered IO.
mem=x If x == malloc, use malloc for buffers. If x == shm,
use shared memory for buffers. If x == mmap, use
anonymous mmap.
exitall When one thread quits, terminate the others
bwavgtime=x Average bandwidth stats over an x msec window.
create_serialize=x If 'x', serialize file creation.
create_fsync=x If 'x', run fsync() after file creation.
unlink If set, unlink files when done.
loops=x Run the job 'x' number of times.
verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
use crc32 for verifies. md5 is 'safer', but crc32 is
a lot faster. Only makes sense for writing to a file.
stonewall Wait for preceeding jobs to end before running.
numjobs=x Create 'x' similar entries for this job
thread Use pthreads instead of forked jobs
zonesize=x
zoneskip=y Zone options must be paired. If given, the job
will skip y bytes for every x read/written. This
can be used to gauge hard drive speed over the entire
platter, without reading everything. Both x/y can
include k/m/g suffix.
iolog=x Open and read io pattern from file 'x'. The file must
contain one io action per line in the following format:
rw, offset, length
where with rw=0/1 for read/write, and the offset
and length entries being in bytes.
write_iolog=x Write an iolog to file 'x' in the same format as iolog.
The iolog options are exclusive, if both given the
read iolog will be performed.
write_bw_log Write a bandwidth log.
write_lat_log Write a latency log.
lockmem=x Lock down x amount of memory on the machine, to
simulate a machine with less memory available. x can
include k/m/g suffix.
nice=x Run job at given nice value.
exec_prerun=x Run 'x' before job io is begun.
exec_postrun=x Run 'x' after job io has finished.
ioscheduler=x Use ioscheduler 'x' for this job.
cpuload=x For a CPU io thread, percentage of CPU time to attempt
to burn.
cpuchunks=x Split burn cycles into pieces of x.
Author
------
Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
of the Linux IO subsystem and schedulers. He got tired of writing
specific test applications to simulate a given workload, and found that
the existing io benchmark/test tools out there weren't flexible enough
to do what he wanted.
Jens Axboe <axboe@kernel.dk> 20060905