[fio.git] / README

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


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
        --timeout       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

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
	timeout=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
Commit	Line	Data
	1	fio
	2	---
	3
	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
	9	one wants to simulate.
	10
	11
	12	Source
	13	------
	14
	15	fio resides in a git repo, the canonical place is:
	16
	17	git://brick.kernel.dk/data/git/fio.git
	18
	19	Snapshots are frequently generated and they include the git meta data as
	20	well. You can download them here:
	21
	22	http://brick.kernel.dk/snaps/
	23
	24	Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository, you
	25	can find them here:
	26
	27	http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
	28
	29
	30	Building
	31	--------
	32
	33	Just type 'make' and 'make install'. If on FreeBSD, for now you have to
	34	specify the FreeBSD Makefile with -f, eg:
	35
	36	$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
	37
	38	Likewise with OpenSolaris, use the Makefile.solaris to compile there.
	39	This might change in the future if I opt for an autoconf type setup.
	40
	41
	42	Command line
	43	------------
	44
	45	$ fio
	46	--output Write output to file
	47	--timeout Runtime in seconds
	48	--latency-log Generate per-job latency logs
	49	--bandwidth-log Generate per-job bandwidth logs
	50	--minimal Minimal (terse) output
	51	--version Print version info and exit
	52
	53	Any parameters following the options will be assumed to be job files,
	54	unless they match a job file parameter. You can add as many as you want,
	55	each job file will be regarded as a separate group and fio will stonewall
	56	its execution.
	57
	58
	59	Job file
	60	--------
	61
	62	See the HOWTO file for a more detailed description of parameters and what
	63	they mean. This file contains the terse version. Only a few options can
	64	be controlled with command line parameters, generally it's a lot easier to
	65	just write a simple job file to describe the workload. The job file format
	66	is in the ini style format, as it's easy to read and write for the user.
	67
	68	The job file parameters are:
	69
	70	name=x Use 'x' as the identifier for this job.
	71	directory=x Use 'x' as the top level directory for storing files
	72	filename=x Force the use of 'x' as the filename for all files
	73	in this thread. If not given, fio will make up
	74	a suitable filename based on the thread and file
	75	number.
	76	rw=x 'x' may be: read, randread, write, randwrite,
	77	rw (read-write mix), randrw (read-write random mix)
	78	rwmixcycle=x Base cycle for switching between read and write
	79	in msecs.
	80	rwmixread=x 'x' percentage of rw mix ios will be reads. If
	81	rwmixwrite is also given, the last of the two will
	82	be used if they don't add up to 100%.
	83	rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
	84	rwmixread.
	85	rand_repeatable=x The sequence of random io blocks can be repeatable
	86	across runs, if 'x' is 1.
	87	size=x Set file size to x bytes (x string can include k/m/g)
	88	ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
	89	posixaio for POSIX aio, sync for regular read/write io,
	90	mmap for mmap'ed io, splice for using splice/vmsplice,
	91	or sgio for direct SG_IO io. The latter only works on
	92	Linux on SCSI (or SCSI-like devices, such as
	93	usb-storage or sata/libata driven) devices. Fio also
	94	has a null io engine, which is mainly used for testing
	95	fio itself.
	96	iodepth=x For async io, allow 'x' ios in flight
	97	overwrite=x If 'x', layout a write file first.
	98	nrfiles=x Spread io load over 'x' number of files per job,
	99	if possible.
	100	prio=x Run io at prio X, 0-7 is the kernel allowed range
	101	prioclass=x Run io at prio class X
	102	bs=x Use 'x' for thread blocksize. May include k/m postfix.
	103	bsrange=x-y Mix thread block sizes randomly between x and y. May
	104	also include k/m postfix.
	105	direct=x 1 for direct IO, 0 for buffered IO
	106	thinktime=x "Think" x usec after each io
	107	rate=x Throttle rate to x KiB/sec
	108	ratemin=x Quit if rate of x KiB/sec can't be met
	109	ratecycle=x ratemin averaged over x msecs
	110	cpumask=x Only allow job to run on CPUs defined by mask.
	111	fsync=x If writing with buffered IO, fsync after every
	112	'x' blocks have been written.
	113	end_fsync=x If 'x', run fsync() after end-of-job.
	114	startdelay=x Start this thread x seconds after startup
	115	timeout=x Terminate x seconds after startup. Can include a
	116	normal time suffix if not given in seconds, such as
	117	'm' for minutes, 'h' for hours, and 'd' for days.
	118	offset=x Start io at offset x (x string can include k/m/g)
	119	invalidate=x Invalidate page cache for file prior to doing io
	120	sync=x Use sync writes if x and writing buffered IO.
	121	mem=x If x == malloc, use malloc for buffers. If x == shm,
	122	use shared memory for buffers. If x == mmap, use
	123	anonymous mmap.
	124	exitall When one thread quits, terminate the others
	125	bwavgtime=x Average bandwidth stats over an x msec window.
	126	create_serialize=x If 'x', serialize file creation.
	127	create_fsync=x If 'x', run fsync() after file creation.
	128	unlink If set, unlink files when done.
	129	loops=x Run the job 'x' number of times.
	130	verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
	131	use crc32 for verifies. md5 is 'safer', but crc32 is
	132	a lot faster. Only makes sense for writing to a file.
	133	stonewall Wait for preceeding jobs to end before running.
	134	numjobs=x Create 'x' similar entries for this job
	135	thread Use pthreads instead of forked jobs
	136	zonesize=x
	137	zoneskip=y Zone options must be paired. If given, the job
	138	will skip y bytes for every x read/written. This
	139	can be used to gauge hard drive speed over the entire
	140	platter, without reading everything. Both x/y can
	141	include k/m/g suffix.
	142	iolog=x Open and read io pattern from file 'x'. The file must
	143	contain one io action per line in the following format:
	144	rw, offset, length
	145	where with rw=0/1 for read/write, and the offset
	146	and length entries being in bytes.
	147	write_iolog=x Write an iolog to file 'x' in the same format as iolog.
	148	The iolog options are exclusive, if both given the
	149	read iolog will be performed.
	150	write_bw_log Write a bandwidth log.
	151	write_lat_log Write a latency log.
	152	lockmem=x Lock down x amount of memory on the machine, to
	153	simulate a machine with less memory available. x can
	154	include k/m/g suffix.
	155	nice=x Run job at given nice value.
	156	exec_prerun=x Run 'x' before job io is begun.
	157	exec_postrun=x Run 'x' after job io has finished.
	158	ioscheduler=x Use ioscheduler 'x' for this job.
	159	cpuload=x For a CPU io thread, percentage of CPU time to attempt
	160	to burn.
	161	cpuchunks=x Split burn cycles into pieces of x.
	162
	163
	164	Author
	165	------
	166
	167	Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
	168	of the Linux IO subsystem and schedulers. He got tired of writing
	169	specific test applications to simulate a given workload, and found that
	170	the existing io benchmark/test tools out there weren't flexible enough
	171	to do what he wanted.
	172
	173	Jens Axboe <axboe@kernel.dk> 20060905
	174