[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 for
SUSE variants, you can find them here:

http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio

Dag Wieërs has RPMs for Red Hat related distros, find them here:

http://dag.wieers.com/rpm/packages/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.
	description=x	'x' is a text description of the 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, syslet-rw for syslet driven
			read/write, splice for using splice/vmsplice,
			sgio for direct SG_IO io, or net for network io. sgio
			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
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 for
	25	SUSE variants, you can find them here:
	26
	27	http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
	28
	29	Dag Wieërs has RPMs for Red Hat related distros, find them here:
	30
	31	http://dag.wieers.com/rpm/packages/fio/
	32
	33
	34	Mailing list
	35	------------
	36
	37	There's a mailing list associated with fio. It's meant for general
	38	discussion, bug reporting, questions - basically anything that has to
	39	do with fio. An automated mail detailing recent commits is automatically
	40	sent to the list at most daily. The list address is fio-devel@kernel.dk,
	41	subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
	42
	43
	44	Building
	45	--------
	46
	47	Just type 'make' and 'make install'. If on FreeBSD, for now you have to
	48	specify the FreeBSD Makefile with -f, eg:
	49
	50	$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
	51
	52	Likewise with OpenSolaris, use the Makefile.solaris to compile there.
	53	This might change in the future if I opt for an autoconf type setup.
	54
	55
	56	Command line
	57	------------
	58
	59	$ fio
	60	--output Write output to file
	61	--runtime Runtime in seconds
	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
	66	--help Print this page
	67	--cmdhelp=cmd Print command help, "all" for all of them
	68
	69	Any parameters following the options will be assumed to be job files,
	70	unless they match a job file parameter. You can add as many as you want,
	71	each job file will be regarded as a separate group and fio will stonewall
	72	its execution.
	73
	74
	75	Job file
	76	--------
	77
	78	See the HOWTO file for a more detailed description of parameters and what
	79	they mean. This file contains the terse version. Only a few options can
	80	be controlled with command line parameters, generally it's a lot easier to
	81	just write a simple job file to describe the workload. The job file format
	82	is in the ini style format, as it's easy to read and write for the user.
	83
	84	The job file parameters are:
	85
	86	name=x Use 'x' as the identifier for this job.
	87	description=x 'x' is a text description of the job.
	88	directory=x Use 'x' as the top level directory for storing files
	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.
	93	rw=x 'x' may be: read, randread, write, randwrite,
	94	rw (read-write mix), randrw (read-write random mix)
	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.
	102	rand_repeatable=x The sequence of random io blocks can be repeatable
	103	across runs, if 'x' is 1.
	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,
	107	mmap for mmap'ed io, syslet-rw for syslet driven
	108	read/write, splice for using splice/vmsplice,
	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.
	114	iodepth=x For async io, allow 'x' ios in flight
	115	overwrite=x If 'x', layout a write file first.
	116	nrfiles=x Spread io load over 'x' number of files per job,
	117	if possible.
	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.
	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.
	132	startdelay=x Start this thread x seconds after startup
	133	runtime=x Terminate x seconds after startup. Can include a
	134	normal time suffix if not given in seconds, such as
	135	'm' for minutes, 'h' for hours, and 'd' for days.
	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
	138	sync=x Use sync writes if x and writing buffered IO.
	139	mem=x If x == malloc, use malloc for buffers. If x == shm,
	140	use shared memory for buffers. If x == mmap, use
	141	anonymous mmap.
	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.
	146	unlink If set, unlink files when done.
	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
	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.
	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.
	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.
	168	write_bw_log Write a bandwidth log.
	169	write_lat_log Write a latency log.
	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.
	173	nice=x Run job at given nice value.
	174	exec_prerun=x Run 'x' before job io is begun.
	175	exec_postrun=x Run 'x' after job io has finished.
	176	ioscheduler=x Use ioscheduler 'x' for this job.
	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.
	180
	181
	182	Author
	183	------
	184
	185	Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
	186	of the Linux IO subsystem and schedulers. He got tired of writing
	187	specific test applications to simulate a given workload, and found that
	188	the existing io benchmark/test tools out there weren't flexible enough
	189	to do what he wanted.
	190
	191	Jens Axboe <axboe@kernel.dk> 20060905
	192