-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
- 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.
- iodepth=x For async io, allow 'x' ios in flight
- overwrite=x If 'x', layout a write file first.
- 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, fsync after every x blocks have been written
- 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
- mem=x If x == malloc, use malloc for buffers. If x == shm,
- use shm for buffers. If x == mmap, use anon 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.
- end_fsync=x If 'x', run fsync() after end-of-job.
- 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.
- 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.
-
-
-Examples using a job file
--------------------------
-
-Example 1) Two random readers
-
-Lets say we want to simulate two threads reading randomly from a file
-each. They will be doing IO in 4KiB chunks, using raw (O_DIRECT) IO.
-Since they share most parameters, we'll put those in the [global]
-section. Job 1 will use a 128MiB file, job 2 will use a 256MiB file.
-
-; ---snip---
-
-[global]
-ioengine=sync ; regular read/write(2), the default
-rw=randread
-bs=4k
-direct=1
-
-[file1]
-size=128m
-
-[file2]
-size=256m
-
-; ---snip---
-
-Generally the [] bracketed name specifies a file name, but the "global"
-keyword is reserved for setting options that are inherited by each
-subsequent job description. It's possible to have several [global]
-sections in the job file, each one adds options that are inherited by
-jobs defined below it. The name can also point to a block device, such
-as /dev/sda. To run the above job file, simply do:
-
-$ fio jobfile
-
-Example 2) Many random writers
-
-Say we want to exercise the IO subsystem some more. We'll define 64
-threads doing random buffered writes. We'll let each thread use async io
-with a depth of 4 ios in flight. A job file would then look like this:
-
-; ---snip---
-
-[global]
-ioengine=libaio
-iodepth=4
-rw=randwrite
-bs=32k
-direct=0
-size=64m
-
-[files]
-numjobs=64
-
-; ---snip---
-
-This will create files.[0-63] and perform the random writes to them.
-
-There are endless ways to define jobs, the examples/ directory contains
-a few more examples.
-
-
-Interpreting the output
------------------------
-
-fio spits out a lot of output. While running, fio will display the
-status of the jobs created. An example of that would be:
-
-Threads running: 1: [_r] [24.79% done] [eta 00h:01m:31s]
-
-The characters inside the square brackets denote the current status of
-each thread. The possible values (in typical life cycle order) are:
-
-Idle Run
----- ---
-P Thread setup, but not started.
-C Thread created.
-I Thread initialized, waiting.
- R Running, doing sequential reads.
- r Running, doing random reads.
- W Running, doing sequential writes.
- w Running, doing random writes.
- M Running, doing mixed sequential reads/writes.
- m Running, doing mixed random reads/writes.
- F Running, currently waiting for fsync()
-V Running, doing verification of written data.
-E Thread exited, not reaped by main thread yet.
-_ Thread reaped.
-
-The other values are fairly self explanatory - number of threads
-currently running and doing io, and the estimated completion percentage
-and time for the running group. It's impossible to estimate runtime
-of the following groups (if any).
-
-When fio is done (or interrupted by ctrl-c), it will show the data for
-each thread, group of threads, and disks in that order. For each data
-direction, the output looks like:
-
-Client1 (g=0): err= 0:
- write: io= 32MiB, bw= 666KiB/s, runt= 50320msec
- slat (msec): min= 0, max= 136, avg= 0.03, dev= 1.92
- clat (msec): min= 0, max= 631, avg=48.50, dev=86.82
- bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, dev=681.68
- cpu : usr=1.49%, sys=0.25%, ctx=7969
-
-The client number is printed, along with the group id and error of that
-thread. Below is the io statistics, here for writes. In the order listed,
-they denote:
-
-io= Number of megabytes io performed
-bw= Average bandwidth rate
-runt= The runtime of that thread
- slat= Submission latency (avg being the average, dev being the
- standard deviation). This is the time it took to submit
- the io. For sync io, the slat is really the completion
- latency, since queue/complete is one operation there.
- clat= Completion latency. Same names as slat, this denotes the
- time from submission to completion of the io pieces. For
- sync io, clat will usually be equal (or very close) to 0,
- as the time from submit to complete is basically just
- CPU time (io has already been done, see slat explanation).
- bw= Bandwidth. Same names as the xlat stats, but also includes
- an approximate percentage of total aggregate bandwidth
- this thread received in this group. This last value is
- only really useful if the threads in this group are on the
- same disk, since they are then competing for disk access.
-cpu= CPU usage. User and system time, along with the number
- of context switches this thread went through.
-
-After each client has been listed, the group statistics are printed. They
-will look like this:
-
-Run status group 0 (all jobs):
- READ: io=64MiB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec
- WRITE: io=64MiB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec
-
-For each data direction, it prints:
-
-io= Number of megabytes io performed.
-aggrb= Aggregate bandwidth of threads in this group.
-minb= The minimum average bandwidth a thread saw.
-maxb= The maximum average bandwidth a thread saw.
-mint= The smallest runtime of the threads in that group.
-maxt= The longest runtime of the threads in that group.
-
-And finally, the disk statistics are printed. They will look like this:
-
-Disk stats (read/write):
- sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
-
-Each value is printed for both reads and writes, with reads first. The
-numbers denote:
-
-ios= Number of ios performed by all groups.
-merge= Number of merges io the io scheduler.
-ticks= Number of ticks we kept the disk busy.
-io_queue= Total time spent in the disk queue.
-util= The disk utilization. A value of 100% means we kept the disk
- busy constantly, 50% would be a disk idling half of the time.
-
-
-Terse output