[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://git.kernel.dk/fio.git

The http protocol also works, path is the same.

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/

Mandriva has integrated fio into their package repository, so installing
on that distro should be as easy as typing 'urpmi 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
	--showcmd	Turn a job file into command line options
	--readonly	Turn on safety read-only checks
	--eta=when	When ETA estimate should be printed
			May be "always", "never" or "auto"


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.

The --readonly switch is an extra safety guard to prevent accidentically
turning on a write setting when that is not desired. Fio will only write
if rw=write/randwrite/rw/randrw is given, but this extra safety net can
be used as an extra precaution. It will also enable a write check in the
io engine core to prevent an accidental write due to a fio bug.


Job file
--------

See the HOWTO file for a more detailed description of parameters and what
they mean. This file contains the terse version. You can describe big and
complex setups with the command line, but 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 that is 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, net for network io, or cpuio
			for a cycler burner load. 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.
	cpus_allowed=x	Like 'cpumask', but allow text setting of CPU affinity.
	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 usecs.


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://git.kernel.dk/fio.git
	18
	19	The http protocol also works, path is the same.
	20
	21	Snapshots are frequently generated and they include the git meta data as
	22	well. You can download them here:
	23
	24	http://brick.kernel.dk/snaps/
	25
	26	Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository for
	27	SUSE variants, you can find them here:
	28
	29	http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
	30
	31	Dag Wieërs has RPMs for Red Hat related distros, find them here:
	32
	33	http://dag.wieers.com/rpm/packages/fio/
	34
	35	Mandriva has integrated fio into their package repository, so installing
	36	on that distro should be as easy as typing 'urpmi fio'.
	37
	38
	39	Mailing list
	40	------------
	41
	42	There's a mailing list associated with fio. It's meant for general
	43	discussion, bug reporting, questions - basically anything that has to
	44	do with fio. An automated mail detailing recent commits is automatically
	45	sent to the list at most daily. The list address is fio-devel@kernel.dk,
	46	subscribe by sending an empty email to fio-devel+subscribe@kernel.dk.
	47
	48
	49	Building
	50	--------
	51
	52	Just type 'make' and 'make install'. If on FreeBSD, for now you have to
	53	specify the FreeBSD Makefile with -f, eg:
	54
	55	$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
	56
	57	Likewise with OpenSolaris, use the Makefile.solaris to compile there.
	58	This might change in the future if I opt for an autoconf type setup.
	59
	60
	61	Command line
	62	------------
	63
	64	$ fio
	65	--output Write output to file
	66	--runtime Runtime in seconds
	67	--latency-log Generate per-job latency logs
	68	--bandwidth-log Generate per-job bandwidth logs
	69	--minimal Minimal (terse) output
	70	--version Print version info and exit
	71	--help Print this page
	72	--cmdhelp=cmd Print command help, "all" for all of them
	73	--showcmd Turn a job file into command line options
	74	--readonly Turn on safety read-only checks
	75	--eta=when When ETA estimate should be printed
	76	May be "always", "never" or "auto"
	77
	78
	79	Any parameters following the options will be assumed to be job files,
	80	unless they match a job file parameter. You can add as many as you want,
	81	each job file will be regarded as a separate group and fio will stonewall
	82	its execution.
	83
	84	The --readonly switch is an extra safety guard to prevent accidentically
	85	turning on a write setting when that is not desired. Fio will only write
	86	if rw=write/randwrite/rw/randrw is given, but this extra safety net can
	87	be used as an extra precaution. It will also enable a write check in the
	88	io engine core to prevent an accidental write due to a fio bug.
	89
	90
	91	Job file
	92	--------
	93
	94	See the HOWTO file for a more detailed description of parameters and what
	95	they mean. This file contains the terse version. You can describe big and
	96	complex setups with the command line, but generally it's a lot easier to
	97	just write a simple job file to describe the workload. The job file format
	98	is in the ini style format, as that is easy to read and write for the user.
	99
	100	The job file parameters are:
	101
	102	name=x Use 'x' as the identifier for this job.
	103	description=x 'x' is a text description of the job.
	104	directory=x Use 'x' as the top level directory for storing files
	105	filename=x Force the use of 'x' as the filename for all files
	106	in this thread. If not given, fio will make up
	107	a suitable filename based on the thread and file
	108	number.
	109	rw=x 'x' may be: read, randread, write, randwrite,
	110	rw (read-write mix), randrw (read-write random mix)
	111	rwmixcycle=x Base cycle for switching between read and write
	112	in msecs.
	113	rwmixread=x 'x' percentage of rw mix ios will be reads. If
	114	rwmixwrite is also given, the last of the two will
	115	be used if they don't add up to 100%.
	116	rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
	117	rwmixread.
	118	rand_repeatable=x The sequence of random io blocks can be repeatable
	119	across runs, if 'x' is 1.
	120	size=x Set file size to x bytes (x string can include k/m/g)
	121	ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
	122	posixaio for POSIX aio, sync for regular read/write io,
	123	mmap for mmap'ed io, syslet-rw for syslet driven
	124	read/write, splice for using splice/vmsplice,
	125	sgio for direct SG_IO io, net for network io, or cpuio
	126	for a cycler burner load. sgio only works on Linux on
	127	SCSI (or SCSI-like devices, such as usb-storage or
	128	sata/libata driven) devices. Fio also has a null io
	129	engine, which is mainly used for testing fio itself.
	130	iodepth=x For async io, allow 'x' ios in flight
	131	overwrite=x If 'x', layout a write file first.
	132	nrfiles=x Spread io load over 'x' number of files per job,
	133	if possible.
	134	prio=x Run io at prio X, 0-7 is the kernel allowed range
	135	prioclass=x Run io at prio class X
	136	bs=x Use 'x' for thread blocksize. May include k/m postfix.
	137	bsrange=x-y Mix thread block sizes randomly between x and y. May
	138	also include k/m postfix.
	139	direct=x 1 for direct IO, 0 for buffered IO
	140	thinktime=x "Think" x usec after each io
	141	rate=x Throttle rate to x KiB/sec
	142	ratemin=x Quit if rate of x KiB/sec can't be met
	143	ratecycle=x ratemin averaged over x msecs
	144	cpumask=x Only allow job to run on CPUs defined by mask.
	145	cpus_allowed=x Like 'cpumask', but allow text setting of CPU affinity.
	146	fsync=x If writing with buffered IO, fsync after every
	147	'x' blocks have been written.
	148	end_fsync=x If 'x', run fsync() after end-of-job.
	149	startdelay=x Start this thread x seconds after startup
	150	runtime=x Terminate x seconds after startup. Can include a
	151	normal time suffix if not given in seconds, such as
	152	'm' for minutes, 'h' for hours, and 'd' for days.
	153	offset=x Start io at offset x (x string can include k/m/g)
	154	invalidate=x Invalidate page cache for file prior to doing io
	155	sync=x Use sync writes if x and writing buffered IO.
	156	mem=x If x == malloc, use malloc for buffers. If x == shm,
	157	use shared memory for buffers. If x == mmap, use
	158	anonymous mmap.
	159	exitall When one thread quits, terminate the others
	160	bwavgtime=x Average bandwidth stats over an x msec window.
	161	create_serialize=x If 'x', serialize file creation.
	162	create_fsync=x If 'x', run fsync() after file creation.
	163	unlink If set, unlink files when done.
	164	loops=x Run the job 'x' number of times.
	165	verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
	166	use crc32 for verifies. md5 is 'safer', but crc32 is
	167	a lot faster. Only makes sense for writing to a file.
	168	stonewall Wait for preceeding jobs to end before running.
	169	numjobs=x Create 'x' similar entries for this job
	170	thread Use pthreads instead of forked jobs
	171	zonesize=x
	172	zoneskip=y Zone options must be paired. If given, the job
	173	will skip y bytes for every x read/written. This
	174	can be used to gauge hard drive speed over the entire
	175	platter, without reading everything. Both x/y can
	176	include k/m/g suffix.
	177	iolog=x Open and read io pattern from file 'x'. The file must
	178	contain one io action per line in the following format:
	179	rw, offset, length
	180	where with rw=0/1 for read/write, and the offset
	181	and length entries being in bytes.
	182	write_iolog=x Write an iolog to file 'x' in the same format as iolog.
	183	The iolog options are exclusive, if both given the
	184	read iolog will be performed.
	185	write_bw_log Write a bandwidth log.
	186	write_lat_log Write a latency log.
	187	lockmem=x Lock down x amount of memory on the machine, to
	188	simulate a machine with less memory available. x can
	189	include k/m/g suffix.
	190	nice=x Run job at given nice value.
	191	exec_prerun=x Run 'x' before job io is begun.
	192	exec_postrun=x Run 'x' after job io has finished.
	193	ioscheduler=x Use ioscheduler 'x' for this job.
	194	cpuload=x For a CPU io thread, percentage of CPU time to attempt
	195	to burn.
	196	cpuchunks=x Split burn cycles into pieces of x usecs.
	197
	198
	199	Author
	200	------
	201
	202	Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
	203	of the Linux IO subsystem and schedulers. He got tired of writing
	204	specific test applications to simulate a given workload, and found that
	205	the existing io benchmark/test tools out there weren't flexible enough
	206	to do what he wanted.
	207
	208	Jens Axboe <axboe@kernel.dk> 20060905
	209