a string. The following types are used:
str String. This is a sequence of alpha characters.
-int Integer. A whole number value, may be negative.
+int Integer. A whole number value, can be negative. If prefixed with
+ 0x, the integer is assumed to be of base 16 (hexidecimal).
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 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.
+ If the option accepts an upper and lower range, use a colon ':'
+ or minus '-' to seperate such values. See irange.
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
files between threads in a job or several jobs, specify
a filename for each of them to override the default. If
the ioengine used is 'net', the filename is the host and
- port to connect to in the format of =host:port.
-
+ port to connect to in the format of =host/port. If the
+ ioengine is file based, you can specify a number of files
+ by seperating the names with a ':' colon. So if you wanted
+ a job to open /dev/sda and /dev/sdb as the two working files,
+ you would use filename=/dev/sda:/dev/sdb. '-' is a reserved
+ name, meaning stdin or stdout. Which of the two depends
+ on the read/write direction set.
+
+opendir=str Tell fio to recursively add any file it can find in this
+ directory and down the file system tree.
+
+readwrite=str
rw=str Type of io pattern. Accepted values are:
read Sequential reads
For the mixed io types, the default is to split them 50/50.
For certain types of io the result may still be skewed a bit,
- since the speed may be different.
+ since the speed may be different. It is possible to specify
+ a number of IO's to do before getting a new offset - this
+ is only useful for random IO, where fio would normally
+ generate a new random offset for every IO. If you append
+ eg 8 to randread, you would get a new random offset for
+ every 8 IO's. The result would be a seek for only every 8
+ IO's, instead of for every IO. Use rw=randread:8 to specify
+ that.
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
- file already exists, the file size will be adjusted to this
- size if larger than the current file size. If this parameter
- is not given and the file exists, the file size will be used.
-
+fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
+ on what IO patterns it is likely to issue. Sometimes you
+ want to test specific IO patterns without telling the
+ kernel about it, in which case you can disable this option.
+ If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
+ IO and POSIX_FADV_RANDOM for random IO.
+
+size=siint The total size of file io for this job. Fio will run until
+ this many bytes has been transferred, unless runtime is
+ limited by other options (such as 'runtime', for instance).
+ Unless specific nr_files and filesize options are given,
+ fio will divide this size between the available files
+ specified by the job.
+
+filesize=siint Individual file sizes. May be a range, in which case fio
+ will select sizes for files at random within the given range
+ and limited to 'size' in total (if that is given). If not
+ given, each created file is the same size.
+
+blocksize=siint
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
can do so by passing an empty read size - bs=,8k will set
8k for writes and leave the read default value.
+blocksize_range=irange
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
writes, however a second range can be given after a comma.
See bs=.
+blocksize_unaligned
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
direct IO, as that normally requires sector alignment.
+zero_buffers If this option is given, fio will init the IO buffers to
+ all zeroes. The default is to fill them with random data.
+
nrfiles=int Number of files to use for this job. Defaults to 1.
+openfiles=int Number of files to keep open at the same time. Defaults to
+ the same as nrfiles, can be set smaller to limit the number
+ simultaneous opens.
+
file_service_type=str Defines how fio decides which file from a job to
service next. The following types are defined:
roundrobin Round robin over open files. This
is the default.
+ The string can have a number appended, indicating how
+ often to switch to a new file. So if option random:4 is
+ given, fio will switch to a new random file after 4 ios
+ have been issued.
+
ioengine=str Defines how the job issues io to the file. The following
types are defined:
net Transfer over the network to given host:port.
'filename' must be set appropriately to
- filename=host:port regardless of send
+ filename=host/port regardless of send
or receive, if the latter only the port
argument is used.
+ netsplice Like net, but uses splice/vmsplice to
+ map data and send/receive.
+
+ cpuio Doesn't transfer any data, but burns CPU
+ cycles according to the cpuload= and
+ cpucycle= options. Setting cpuload=85
+ will cause that job to do nothing but burn
+ 85% of the CPU.
+
+ guasi The GUASI IO engine is the Generic Userspace
+ Asyncronous Syscall Interface approach
+ to async IO. See
+
+ http://www.xmailserver.org/guasi-lib.html
+
+ for more info on GUASI.
+
external Prefix to specify loading an external
IO engine object file. Append the engine
filename, eg ioengine=external:/tmp/foo.o
end_fsync=bool If true, fsync file contents when the job exits.
+fsync_on_close=bool If true, fio will fsync() a dirty file on close.
+ This differs from end_fsync in that it will happen on every
+ file close, not just at the end of the job.
+
rwmixcycle=int Value in milliseconds describing how often to switch between
reads and writes for a mixed workload. The default is
500 msecs.
new random offset without looking at past io history. This
means that some blocks may not be read or written, and that
some blocks may be read/written more than once. This option
- is mutually exclusive with verify= for that reason.
+ is mutually exclusive with verify= for that reason, since
+ fio doesn't track potential block rewrites which may alter
+ the calculated checksum for that block.
nice=int Run the job with the given nice value. See man nice(2).
rate=int Cap the bandwidth used by this job to this number of KiB/sec.
ratemin=int Tell fio to do whatever it can to maintain at least this
- bandwidth.
+ bandwidth. Failing to meet this requirement, will cause
+ the job to exit.
+
+rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same
+ as rate, just specified independently of bandwidth. If the
+ job is given a block size range instead of a fixed value,
+ the smallest block size is used as the metric.
+
+rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
+ the job to exit.
ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number
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
- sched_setaffinity(2).
+ bitmask of allowed CPU's the job may run on. So if you want
+ the allowed CPUs to be 1 and 5, you would pass the decimal
+ value of (1 << 1 | 1 << 5), or 34. See man
+ sched_setaffinity(2). This may not work on all supported
+ operating systems or kernel versions.
+
+cpus_allowed=str Controls the same options as cpumask, but it allows a text
+ setting of the permitted CPUs instead. So to use CPUs 1 and
+ 5, you would specify cpus_allowed=1,5.
startdelay=int Start this job the specified number of seconds after fio
has started. Only useful if the job file contains several
a specified job will run, so this parameter is handy to
cap the total runtime to a given time.
+time_based If set, fio will run for the duration of the runtime
+ specified even if the file(s) are completey read or
+ written. It will simply loop over the same workload
+ as many times as the runtime allows.
+
invalidate=bool Invalidate the buffer/page cache parts for this file prior
to starting io. Defaults to true.
sync=bool Use sync io for buffered writes. For the majority of the
io engines, this means using O_SYNC.
+iomem=str
mem=str Fio can use various types of memory as the io unit buffer.
The allowed values are:
to repeat the same workload a given number of times. Defaults
to 1.
+do_verify=bool Run the verify phase after a write phase. Only makes sense if
+ verify is set. Defaults to 1.
+
verify=str If writing to a file, fio can verify the file contents
after each iteration of the job. The allowed values are:
md5 Use an md5 sum of the data area and store
it in the header of each block.
+ crc64 Use an experimental crc64 sum of the data
+ area and store it in the header of each
+ block.
+
crc32 Use a crc32 sum of the data area and store
it in the header of each block.
+ crc16 Use a crc16 sum of the data area and store
+ it in the header of each block.
+
+ crc7 Use a crc7 sum of the data area and store
+ it in the header of each block.
+
+ sha512 Use sha512 as the checksum function.
+
+ sha256 Use sha256 as the checksum function.
+
+ meta Write extra information about each io
+ (timestamp, block number etc.). The block
+ number is verified.
+
+ pattern Fill the IO buffers with a specific pattern,
+ that we can use to verify. Depending on the
+ width of the pattern, fio will fill 1/2/3/4
+ bytes of the buffer at the time. The pattern
+ cannot be larger than a 32-bit quantity. The
+ given pattern is given as a postfix to this
+ option, ala: verify=pattern:0x5a. It accepts
+ both hex and dec values.
+
+ null Only pretend to verify. Useful for testing
+ internals with ioengine=null, not for much
+ else.
+
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.
+verifysort=bool If set, fio will sort written verify blocks when it deems
+ it faster to read them back in a sorted manner. This is
+ often the case when overwriting an existing file, since
+ the blocks are already laid out in the file system. You
+ can ignore this option unless doing huge amounts of really
+ fast IO where the red-black tree sorting CPU time becomes
+ significant.
+
+verify_offset=siint Swap the verification header with data somewhere else
+ in the block before writing. Its swapped back before
+ verifying.
+
+verify_interval=siint Write the verification header at a finer granularity
+ than the blocksize. It will be written for chunks the
+ size of header_interval. blocksize should divide this
+ evenly.
+
+verify_fatal=bool Normally fio will keep checking the entire contents
+ before quitting on a block verification failure. If this
+ option is set, fio will exit the job on the first observed
+ failure.
+
stonewall Wait for preceeding jobs in the job file to exit, before
starting this one. Can be used to insert serialization
- points in the job file.
+ points in the job file. A stone wall also implies starting
+ a new reporting group.
+
+new_group Start a new reporting group. If this option isn't given,
+ jobs in a file will be part of the same reporting group
+ unless seperated by a stone wall (or if it's a group
+ by itself, with the numjobs option).
numjobs=int Create the specified number of clones of this job. May be
used to setup a larger number of threads/processes doing
read_iolog=str Open an iolog with the specified file name and replay the
io patterns it contains. This can be used to store a
- workload and replay it sometime later.
+ workload and replay it sometime later. The iolog given
+ may also be a blktrace binary file, which allows fio
+ to replay a workload captured by blktrace. See blktrace
+ for how to capture such logging data. For blktrace replay,
+ the file needs to be turned into a blkparse binary data
+ file first (blktrace <device> -d file_for_fio.bin).
write_bw_log If given, write a bandwidth log of the jobs in this job
file. Can be used to store data of the bandwidth of the
cpuchunks=int If the job is a CPU cycle eater, split the load into
cycles of the given time. In milliseconds.
+disk_util=bool Generate disk utilization statistics, if the platform
+ supports it. Defaults to on.
+
6.0 Interpreting the output
---------------------------
_ Thread reaped.
The other values are fairly self explanatory - number of threads
-currently running and doing io, rate of io since last check, and the estimated
-completion percentage and time for the running group. It's impossible to
-estimate runtime of the following groups (if any).
+currently running and doing io, rate of io since last check (read speed
+listed first, then write speed), 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
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
+ cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17
IO depths : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0%
+ issued r/w: total=0/32768, short=0/0
lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%,
lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0%
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
+ slat= Submission latency (avg being the average, stdev 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.
+ latency, since queue/complete is one operation there. This
+ value can be in miliseconds or microseconds, fio will choose
+ the most appropriate base and print that. In the example
+ above, miliseconds is the best scale.
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,
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.
+ of context switches this thread went through, usage of
+ system and user time, and finally the number of major
+ and minor page faults.
IO depths= The distribution of io depths over the job life time. The
numbers are divided into powers of 2, so for example the
16= entries includes depths up to that value but higher
than the previous entry. In other words, it covers the
range from 16 to 31.
+IO issued= The number of read/write requests issued, and how many
+ of them were short.
IO latencies= The distribution of IO completion latencies. This is the
time from when IO leaves fio and when it gets completed.
The numbers follow the same pattern as the IO depths,
----------------
For scripted usage where you typically want to generate tables or graphs
-of the results, fio can output the results in a comma separated format.
+of the results, fio can output the results in a semicolon 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
+client1;0;0;1906777;1090804;1790;0;0;0.000000;0.000000;0;0;0.000000;0.000000;929380;1152890;25.510151%;1078276.333333;128948.113404;0;0;0;0;0;0.000000;0.000000;0;0;0.000000;0.000000;0;0;0.000000%;0.000000;0.000000;100.000000%;0.000000%;324;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%;0.0%;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%
+;0.0%;0.0%;0.0%;0.0%;0.0%
Split up, the format is as follows:
projects / fio.git / blobdiff