bool Boolean. Usually parsed as an integer, however only defined for
true and false (1 and 0).
irange Integer range with postfix. Allows value range to be given, such
- as 1024-4096. Also see siint.
+ as 1024-4096. A colon may also be used as the seperator, eg
+ 1k:4k. If the option allows two sets of ranges, they can be
+ specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
+ siint.
With the above in mind, here follows the complete list of fio job
parameters.
For certain types of io the result may still be skewed a bit,
since the speed may be different.
+randrepeat=bool For random IO workloads, seed the generator in a predictable
+ way so that results are repeatable across repetitions.
+
size=siint The total size of file io for this job. This may describe
the size of the single file the job uses, or it may be
divided between the number of files in the job. If the
concurrency.
direct=bool If value is true, use non-buffered io. This is usually
- O_DIRECT. Defaults to true.
+ O_DIRECT.
+
+buffered=bool If value is true, use buffered io. This is the opposite
+ of the 'direct' option. Defaults to true.
offset=siint Start io at the given offset in the file. The data before
the given offset will not be touched. This effectively
thinktime=int Stall the job x microseconds after an io has completed before
issuing the next. May be used to simulate processing being
- done by an application.
+ done by an application. See thinktime_blocks.
+
+thinktime_blocks
+ Only valid if thinktime is set - control how many blocks
+ to issue, before waiting 'thinktime' usecs. If not set,
+ defaults to 1 which will make fio wait 'thinktime' usecs
+ after every block.
rate=int Cap the bandwidth used by this job to this number of KiB/sec.
jobs, and you want to delay starting some jobs to a certain
time.
-timeout=int Tell fio to terminate processing after the specified number
+runtime=int Tell fio to terminate processing after the specified number
of seconds. It can be quite hard to determine for how long
a specified job will run, so this parameter is handy to
cap the total runtime to a given time.
shmhuge Same as shm, but use huge pages as backing.
- mmap Use anonymous memory maps as the buffers.
- Allocated through mmap(2).
+ mmap Use mmap to allocate buffers. May either be
+ anonymous memory, or can be file backed if
+ a filename is given after the option. The
+ format is mem=mmap:/path/to/file.
mmaphuge Use a memory mapped huge file as the buffer
backing. Append filename after mmaphuge, ala
mem=mmaphuge:/hugetlbfs/file
The area allocated is a function of the maximum allowed
- bs size for the job, multiplied by the io depth given.
+ bs size for the job, multiplied by the io depth given. Note
+ that for shmhuge and mmaphuge to work, the system must have
+ free huge pages allocated. This can normally be checked
+ and set by reading/writing /proc/sys/vm/nr_hugepages on a
+ Linux system. Fio assumes a huge page is 4MiB in size. So
+ to calculate the number of huge pages you need for a given
+ job file, add up the io depth of all jobs (normally one unless
+ iodepth= is used) and multiply by the maximum bs set. Then
+ divide that number by the huge page size. You can see the
+ size of the huge pages in /proc/meminfo. If no huge pages
+ are allocated by having a non-zero number in nr_hugepages,
+ using mmaphuge or shmhuge will fail. Also see hugepage-size.
+
+ mmaphuge also needs to have hugetlbfs mounted and the file
+ location should point there. So if it's mounted in /huge,
+ you would use mem=mmaphuge:/huge/somefile.
+
+hugepage-size=siint
+ Defines the size of a huge page. Must at least be equal
+ to the system setting, see /proc/meminfo. Defaults to 4MiB.
+ Should probably always be a multiple of megabytes, so using
+ hugepage-size=Xm is the preferred way to set this to avoid
+ setting a non-pow-2 bad value.
exitall When one job finishes, terminate the rest. The default is
to wait for each job to finish, sometimes that is not the
create_fsync=bool fsync the data file after creation. This is the
default.
-unlink Unlink the job files when done. fio defaults to doing this,
+unlink=bool Unlink the job files when done. fio defaults to doing this,
if it created the file itself.
loops=int Run the specified number of iterations of this job. Used
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
+ slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92
+ clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82
+ bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=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
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