could be using splice, async io, or even
SG (SCSI generic sg).
- IO depth If the io engine is async, how large a queueing
+ IO depth If the io engine is async, how large a queuing
depth do we want to maintain?
IO type Should we be doing buffered io, or direct/raw io?
fio does not need to run as root, except if the files or devices specified
in the job section requires that. Some other options may also be restricted,
-such as memory locking, io scheduler switching, and descreasing the nice value.
+such as memory locking, io scheduler switching, and decreasing the nice value.
4.0 Job file format
int Integer. A whole number value, may be negative.
siint SI integer. A whole number value, which may contain a postfix
describing the base of the number. Accepted postfixes are k/m/g,
- meaning kilo, mega, and giga. So if you want to specifiy 4096,
+ meaning kilo, mega, and giga. So if you want to specify 4096,
you could either write out '4096' or just give 4k. The postfixes
signify base 2 values, so 1024 is 1k and 1024k is 1m and so on.
bool Boolean. Usually parsed as an integer, however only defined for
name=str ASCII name of the job. This may be used to override the
name printed by fio for this job. Otherwise the job
name is used. On the command line this parameter has the
- special purpose of also signalling the start of a new
+ special purpose of also signaling the start of a new
job.
directory=str Prefix filenames with this directory. Used to places files
size if larger than the current file size. If this parameter
is not given and the file exists, the file size will be used.
-bs=siint The block size used for the io units. Defaults to 4k.
-
-read_bs=siint
-write_bs=siint If the workload is a mixed read-write workload, you can use
- these options to set seperate block sizes.
+bs=siint The block size used for the io units. Defaults to 4k. Values
+ can be given for both read and writes. If a single siint is
+ given, it will apply to both. If a second siint is specified
+ after a comma, it will apply to writes only. In other words,
+ the format is either bs=read_and_write or bs=read,write.
+ bs=4k,8k will thus use 4k blocks for reads, and 8k blocks
+ for writes. If you only wish to set the write size, you
+ can do so by passing an empty read size - bs=,8k will set
+ 8k for writes and leave the read default value.
bsrange=irange Instead of giving a single block size, specify a range
and fio will mix the issued io block sizes. The issued
io unit will always be a multiple of the minimum value
- given (also see bs_unaligned).
-
-read_bsrange=irange
-write_bsrange=irange
- If the workload is a mixed read-write workload, you can use
- one of these options to set separate block size ranges for
- reads and writes.
+ given (also see bs_unaligned). Applies to both reads and
+ writes, however a second range can be given after a comma.
+ See bs=.
bs_unaligned If this option is given, any byte size value within bsrange
may be used as a block range. This typically wont work with
space to the kernel.
sg SCSI generic sg v3 io. May either be
- syncrhonous using the SG_IO ioctl, or if
+ synchronous using the SG_IO ioctl, or if
the target is an sg character device
we use read(2) and write(2) for asynchronous
io.
32 as a parameter, fio will sync the file for every 32
writes issued. If fio is using non-buffered io, we may
not sync the file. The exception is the sg io engine, which
- syncronizes the disk cache anyway.
+ synchronizes the disk cache anyway.
overwrite=bool If writing to a file, setup the file first and do overwrites.
end_fsync=bool If true, fsync file contents when the job exits.
-rwmixcycle=int Value in miliseconds describing how often to switch between
+rwmixcycle=int Value in milliseconds describing how often to switch between
reads and writes for a mixed workload. The default is
500 msecs.
bandwidth.
ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number
- of miliseconds.
+ of milliseconds.
cpumask=int Set the CPU affinity of this job. The parameter given is a
bitmask of allowed CPU's the job may run on. See man
desired action.
bwavgtime=int Average the calculated bandwidth over the given time. Value
- is specified in miliseconds.
+ is specified in milliseconds.
create_serialize=bool If true, serialize the file creating for the jobs.
This may be handy to avoid interleaving of data
crc32 Use a crc32 sum of the data area and store
it in the header of each block.
- This option can be used for repeated burnin tests of a
+ This option can be used for repeated burn-in tests of a
system to make sure that the written data is also
correctly read back.
percentage of CPU cycles.
cpuchunks=int If the job is a CPU cycle eater, split the load into
- cycles of the given time. In miliseconds.
+ cycles of the given time. In milliseconds.
6.0 Interpreting the output
----------------
For scripted usage where you typically want to generate tables or graphs
-of the results, fio can output the results in a comma seperated format.
+of the results, fio can output the results in a comma separated format.
The format is one long line of values, such as:
client1,0,0,936,331,2894,0,0,0.000000,0.000000,1,170,22.115385,34.290410,16,714,84.252874%,366.500000,566.417819,3496,1237,2894,0,0,0.000000,0.000000,0,246,6.671625,21.436952,0,2534,55.465300%,1406.600000,2008.044216,0.000000%,0.431928%,1109
KiB IO, bandwidth (KiB/sec), runtime (msec)
Submission latency: min, max, mean, deviation
Completion latency: min, max, mean, deviation
- Bw: min, max, aggreate percentage of total, mean, deviation
+ Bw: min, max, aggregate percentage of total, mean, deviation
WRITE status:
KiB IO, bandwidth (KiB/sec), runtime (msec)
Submission latency: min, max, mean, deviation
Completion latency: min, max, mean, deviation
- Bw: min, max, aggreate percentage of total, mean, deviation
+ Bw: min, max, aggregate percentage of total, mean, deviation
CPU usage: user, system, context switches
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