path: root/README
diff options
authorJens Axboe <>2013-04-10 22:13:30 +0200
committerJens Axboe <>2013-04-10 22:13:30 +0200
commit8079cb463d0934ef458788030922923ce4be1ac0 (patch)
tree30db3d24a65641f6496d37080dfe440255db0a61 /README
parent7fb6d4530b2018064f8011f7ff9e4f673002f615 (diff)
README: remove partial option list
The HOWTO or man page should be used, since either of those has the full list of option keywords. Signed-off-by: Jens Axboe <>
Diffstat (limited to 'README')
1 files changed, 3 insertions, 109 deletions
diff --git a/README b/README
index 317ddec6..8db962b6 100644
--- a/README
+++ b/README
@@ -224,115 +224,9 @@ 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, windowsaio for Windows 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, rdma for RDMA 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.
- numa_cpu_nodes=x,y-z Allow job to run on specified NUMA nodes' CPU.
- numa_mem_policy=m:x,y-z Setup numa memory allocation policy.
- 'm' stands for policy, such as local, interleave,
- bind, prefer, local. 'x, y-z' are numa node(s) for
- memory allocation according to policy.
- 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.
- read_iolog=x Open and read io pattern from file 'x'. The file format
- is described in the HOWTO.
- 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. Specify a separate file
- for each job, otherwise the iologs will be interspersed
- and the file may be corrupt.
- 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.
+The HOWTO or man page has a full list of all options, along with
+descriptions, etc. The --cmdhelp option also lists all options. If
+used with an option argument, it will detail that particular option.