a string. The following types are used:
str String. This is a sequence of alpha characters.
-int Integer. A whole number value, can be negative.
+int Integer. A whole number value, can be negative. If prefixed with
+ 0x, the integer is assumed to be of base 16 (hexadecimal).
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.
+ or minus '-' to separate 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
- as 1024-4096. A colon may also be used as the seperator, eg
+ as 1024-4096. A colon may also be used as the separator, 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.
the ioengine used is 'net', the filename is the host and
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
+ by separating 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
opendir=str Tell fio to recursively add any file it can find in this
directory and down the file system tree.
+lockfile=str Fio defaults to not doing any locking files before it does
+ IO to them. If a file or file descriptor is shared, fio
+ can serialize IO to that file to make the end result
+ consistent. This is usual for emulating real workloads that
+ share files. The lock modes are:
+
+ none No locking. The default.
+ exclusive Only one thread/process may do IO,
+ excluding all others.
+ readwrite Read-write locking on the file. Many
+ readers may access the file at the
+ same time, but writes get exclusive
+ access.
+
+ The option may be post-fixed with a lock batch number. If
+ set, then each thread/process may do that amount of IOs to
+ the file before giving up the lock. Since lock acquisition is
+ expensive, batching the lock/unlocks will speed up IO.
+
readwrite=str
rw=str Type of io pattern. Accepted values are:
and limited to 'size' in total (if that is given). If not
given, each created file is the same size.
+fill_device=bool Sets size to something really large and waits for ENOSPC (no
+ space left on device) as the terminating condition. Only makes
+ sense with sequential write.
+
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
writes, however a second range can be given after a comma.
See bs=.
+bssplit=str Sometimes you want even finer grained control of the
+ block sizes issued, not just an even split between them.
+ This option allows you to weight various block sizes,
+ so that you are able to define a specific amount of
+ block sizes issued. The format for this option is:
+
+ bssplit=blocksize/percentage:blocksize/percentage
+
+ for as many block sizes as needed. So if you want to define
+ a workload that has 50% 64k blocks, 10% 4k blocks, and
+ 40% 32k blocks, you would write:
+
+ bssplit=4k/10:64k/50:32k/40
+
+ Ordering does not matter. If the percentage is left blank,
+ fio will fill in the remaining values evenly. So a bssplit
+ option like this one:
+
+ bssplit=4k/50:1k/:32k/
+
+ would have 50% 4k ios, and 25% 1k and 32k ios. The percentages
+ always add up to 100, if bssplit is given a range that adds
+ up to more, it will error out.
+
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
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.
+refill_buffers If this option is given, fio will refill the IO buffers
+ on every submit. The default is to only fill it at init
+ time and reuse that data. Only makes sense if zero_buffers
+ isn't specified, naturally. If data verification is enabled,
+ refill_buffers is also automatically enabled.
+
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
sync Basic read(2) or write(2) io. lseek(2) is
used to position the io location.
+ psync Basic pread(2) or pwrite(2) io.
+
+ vsync Basic readv(2) or writev(2) IO.
+
libaio Linux native asynchronous io.
posixaio glibc posix asynchronous io.
+ solarisaio Solaris native asynchronous io.
+
mmap File is memory mapped and data copied
to/from using memcpy(3).
netsplice Like net, but uses splice/vmsplice to
map data and send/receive.
- cpu Doesn't transfer any data, but burns CPU
+ 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.
+ 85% of the CPU. In case of SMP machines,
+ use numjobs=<no_of_cpu> to get desired CPU
+ usage, as the cpuload only loads a single
+ CPU at the desired rate.
guasi The GUASI IO engine is the Generic Userspace
Asyncronous Syscall Interface approach
job, can be overridden with a larger value for higher
concurrency.
+iodepth_batch_submit=int
iodepth_batch=int This defines how many pieces of IO to submit at once.
- It defaults to the same as iodepth, but can be set lower
- if one so desires.
+ It defaults to 1 which means that we submit each IO
+ as soon as it is available, but can be raised to submit
+ bigger batches of IO at the time.
+
+iodepth_batch_complete=int This defines how many pieces of IO to retrieve
+ at once. It defaults to 1 which means that we'll ask
+ for a minimum of 1 IO in the retrieval process from
+ the kernel. The IO retrieval will go on until we
+ hit the limit set by iodepth_low. If this variable is
+ set to 0, then fio will always check for completed
+ events before queuing more IO. This helps reduce
+ IO latency, at the cost of more retrieval system calls.
iodepth_low=int The low water mark indicating when to start filling
the queue again. Defaults to the same as iodepth, meaning
not sync the file. The exception is the sg io engine, which
synchronizes the disk cache anyway.
-overwrite=bool If writing to a file, setup the file first and do overwrites.
+overwrite=bool If true, writes to a file will always overwrite existing
+ data. If the file doesn't already exist, it will be
+ created before the write phase begins. If the file exists
+ and is large enough for the specified write phase, nothing
+ will be done.
end_fsync=bool If true, fsync file contents when the job exits.
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.
-
rwmixread=int How large a percentage of the mix should be reads.
rwmixwrite=int How large a percentage of the mix should be writes. If both
fio doesn't track potential block rewrites which may alter
the calculated checksum for that block.
+softrandommap See norandommap. If fio runs with the random block map enabled
+ and it fails to allocate the map, if this option is set it
+ will continue without a random block map. As coverage will
+ not be as complete as with random maps, this option is
+ disabled by default.
+
nice=int Run the job with the given nice value. See man nice(2).
prio=int Set the io priority value of this job. Linux limits us 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
+ specified even if the file(s) are completely read or
written. It will simply loop over the same workload
as many times as the runtime allows.
default.
unlink=bool Unlink the job files when done. Not the default, as repeated
- runs of that job would then waste time recreating the fileset
- again and again.
+ runs of that job would then waste time recreating the file
+ set again and again.
loops=int Run the specified number of iterations of this job. Used
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.
+
null Only pretend to verify. Useful for testing
internals with ioengine=null, not for much
else.
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_pattern=int If set, fio will fill the io buffers with this
+ pattern. Fio defaults to filling with totally random
+ bytes, but sometimes it's interesting to fill with a known
+ pattern for io verification purposes. Depending on the
+ width of the pattern, fio will fill 1/2/3/4 bytes of the
+ buffer at the time. The verify_pattern cannot be larger than
+ a 32-bit quantity.
+
+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
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
+ unless separated 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
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%
+ submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
+ complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=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%
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. This
- value can be in miliseconds or microseconds, fio will choose
+ value can be in milliseconds or microseconds, fio will choose
the most appropriate base and print that. In the example
- above, miliseconds is the best scale.
+ above, milliseconds 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 submit= How many pieces of IO were submitting in a single submit
+ call. Each entry denotes that amount and below, until
+ the previous entry - eg, 8=100% mean that we submitted
+ anywhere in between 5-8 ios per submit call.
+IO complete= Like the above submit number, but for completions instead.
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
Submission latency: min, max, mean, deviation
Completion latency: min, max, mean, deviation
Bw: min, max, aggregate percentage of total, mean, deviation
- CPU usage: user, system, context switches
+ CPU usage: user, system, context switches, major faults, minor faults
IO depths: <=1, 2, 4, 8, 16, 32, >=64
IO latencies: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000
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