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. If prefixed with
- 0x, the integer is assumed to be of base 16 (hexadecimal).
time Integer with possible time postfix. In seconds unless otherwise
specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds,
minutes, and hours.
-siint SI integer. A whole number value, which may contain a postfix
+int 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 separate such values. See irange.
+ or minus '-' to separate such values. May also include a prefix
+ to indicate numbers base. If 0x is used, the number is assumed to
+ be hexadecimal. 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 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.
+ int.
With the above in mind, here follows the complete list of fio job
parameters.
thread number, and file number. If you want to share
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. If the
- ioengine is file based, you can specify a number of files
- 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
- on the read/write direction set.
+ the ioengine used is 'net', the filename is the host, port,
+ and protocol to use in the format of =host/port/protocol.
+ See ioengine=net for more. If the ioengine is file based, you
+ can specify a number of files 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 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.
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
+size=int 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
+filesize=int 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.
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
- given, it will apply to both. If a second siint is specified
+blocksize=int
+bs=int The block size used for the io units. Defaults to 4k. Values
+ can be given for both read and writes. If a single int is
+ given, it will apply to both. If a second int 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
roundrobin Round robin over open files. This
is the default.
+ sequential Finish one file before moving on to
+ the next. Multiple files can still be
+ open depending on 'openfiles'.
+
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
vsync Basic readv(2) or writev(2) IO.
- libaio Linux native asynchronous io.
+ libaio Linux native asynchronous io. Note that Linux
+ may only support queued behaviour with
+ non-buffered IO (set direct=1 or buffered=0).
posixaio glibc posix asynchronous io.
net Transfer over the network to given host:port.
'filename' must be set appropriately to
- filename=host/port regardless of send
+ filename=host/port/protocol regardless of send
or receive, if the latter only the port
- argument is used.
+ argument is used. 'host' may be an IP address
+ or hostname, port is the port number to be used,
+ and protocol may be 'udp' or 'tcp'. If no
+ protocol is given, TCP is used.
netsplice Like net, but uses splice/vmsplice to
map data and send/receive.
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
+offset=int Start io at the given offset in the file. The data before
the given offset will not be touched. This effectively
caps the file size at real_size - offset.
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, since
- fio doesn't track potential block rewrites which may alter
- the calculated checksum for that block.
+ is mutually exclusive with verify= if and only if multiple
+ blocksizes (via bsrange=) are used, since fio only tracks
+ complete rewrites of blocks.
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
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.
+ operating systems or kernel versions. This option doesn't
+ work well for a higher CPU count than what you can store in
+ an integer mask, so it can only control cpus 1-32. For
+ boxes with larger CPU counts, use cpus_allowed.
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.
+ 5, you would specify cpus_allowed=1,5. This options also
+ allows a range of CPUs. Say you wanted a binding to CPUs
+ 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15.
startdelay=time Start this job the specified number of seconds after fio
has started. Only useful if the job file contains several
location should point there. So if it's mounted in /huge,
you would use mem=mmaphuge:/huge/somefile.
-hugepage-size=siint
+hugepage-size=int
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
create_fsync=bool fsync the data file after creation. This is the
default.
+create_on_open=bool Don't pre-setup the files for IO, just create open()
+ when it's time to do IO to that file.
+
unlink=bool Unlink the job files when done. Not the default, as repeated
runs of that job would then waste time recreating the file
set again and again.
fast IO where the red-black tree sorting CPU time becomes
significant.
-verify_offset=siint Swap the verification header with data somewhere else
+verify_offset=int 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
+verify_interval=int 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.
given, fio will use pthread_create(3) to create threads
instead.
-zonesize=siint Divide a file into zones of the specified size. See zoneskip.
+zonesize=int Divide a file into zones of the specified size. See zoneskip.
-zoneskip=siint Skip the specified number of bytes when zonesize data has
+zoneskip=int Skip the specified number of bytes when zonesize data has
been read. The two zone options can be used to only do
io on zones of a file.
The actual log names will be foo_clat.log and foo_slat.log.
This helps fio_generate_plot fine the logs automatically.
-lockmem=siint Pin down the specified amount of memory with mlock(2). Can
+lockmem=int Pin down the specified amount of memory with mlock(2). Can
potentially be used instead of removing memory or booting
with less memory to simulate a smaller amount of memory.
we only do about 0.4% of the gtod() calls we would have
done if all time keeping was enabled.
+gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of
+ execution to just getting the current time. Fio (and
+ databases, for instance) are very intensive on gettimeofday()
+ calls. With this option, you can set one CPU aside for
+ doing nothing but logging current time to a shared memory
+ location. Then the other threads/processes that run IO
+ workloads need only copy that segment, instead of entering
+ the kernel with a gettimeofday() call. The CPU set aside
+ for doing these time calls will be excluded from other
+ uses. Fio will manually clear it from the CPU mask of other
+ jobs.
+
6.0 Interpreting the output
---------------------------
projects / fio.git / blobdiff