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, and development - 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@vger.kernel.org, subscribe by sending an email to

majordomo@vger.kernel.org with

subscribe fio

in the body of the email. There is no archive for the new list yet,

archives for the old list can be found here:

http://maillist.kernel.dk/fio-devel/

Building

--------

Just type 'make' and 'make install'. If on FreeBSD, for now you have to

specify the FreeBSD Makefile with -f and use gmake (not make), eg:

$ gmake -f Makefile.Freebsd && gmake -f Makefile.FreeBSD install

Likewise with OpenSolaris, use the Makefile.solaris to compile there.

The OpenSolaris make should work fine. This might change in the

future if I opt for an autoconf type setup.

If your compile fails with an error like this:

CC gettime.o

In file included from fio.h:23,

from gettime.c:8:

os/os.h:15:20: error: libaio.h: No such file or directory

In file included from gettime.c:8:

fio.h:119: error: field 'iocb' has incomplete type

make: *** [gettime.o] Error 1

Check that you have the libaio development package installed. On RPM

based distros, it's typically called libaio-devel.

Command line

------------

$ fio

--debug Enable some debugging options (see below)

--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

--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, preventing writes

--eta=when When ETA estimate should be printed

May be "always", "never" or "auto"

--section=name Only run specified section in job file

--alloc-size=kb Set smalloc pool to this size in kb (def 1024)

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.

The debug switch allows adding options that trigger certain logging

options in fio. Currently the options are:

process Dump info related to processes

file Dump info related to file actions

io Dump info related to IO queuing

mem Dump info related to memory allocations

blktrace Dump info related to blktrace setup

verify Dump info related to IO verification

all Enable all debug options

random Dump info related to random offset generation

parse Dump info related to option matching and parsing

diskutil Dump info related to disk utilization updates

job:x Dump info only related to job number x

mutex Dump info only related to mutex up/down ops

? or help Show available debug options.

You can specify as many as you want, eg --debug=file,mem will enable

file and memory debugging.

The section switch is meant to make it easier to ship a bigger job file

instead of several smaller ones. Say you define a job file with light,

moderate, and heavy parts. Then you can ask fio to run the given part

only by giving it a --section=heavy command line option. The section

option only applies to job sections, the reserved 'global' section is

always parsed and taken into account.

Fio has an internal allocator for shared memory called smalloc. It

allocates shared structures from this pool. The pool defaults to 1024k

in size, and can grow to 128 pools. If running large jobs with randommap

enabled it can run out of memory, in which case the --alloc-size switch

is handy for starting with a larger pool size. The backing store is

files in /tmp. Fio cleans up after itself, while it is running you

may see .fio_smalloc.* files in /tmp.

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, solarisaio for Solaris

native async IO, sync for regular read/write io,

psync for regular pread/pwrite io, vsync for regular

readv/writev (with queuing emulation) mmap for mmap'ed

io, syslet-rw for syslet driven read/write, splice for

using splice/vmsplice, sg for direct SG_IO io, net

for network io, or cpuio for a cycler burner load. sg

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 KB/sec

ratemin=x Quit if rate of x KB/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.

For other types of checksumming, see HOWTO.

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.

Platforms

---------

Fio works on (at least) Linux, Solaris, and FreeBSD. Some features and/or

options may only be available on some of the platforms, typically because

those features only apply to that platform (like the solarisaio engine, or

the splice engine on Linux).

Some features are not available on FreeBSD/Solaris even if they could be

implemented, I'd be happy to take patches for that. An example of that is

disk utility statistics and (I think) huge page support, support for that

does exist in FreeBSD/Solaris.

Fio uses pthread mutexes for signalling and locking and FreeBSD does not

support process shared pthread mutexes. As a result, only threads are

supported on FreeBSD. This could be fixed with sysv ipc locking or

other locking alternatives.

Other *BSD platforms are untested, but fio should work there almost out

of the box. Since I don't do test runs or even compiles on those platforms,

your mileage may vary. Sending me patches for other platforms is greatly

appreciated. There's a lot of value in having the same test/benchmark tool

available on all platforms.

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