section residing above it. If the first character in a line is a ';' or a
'#', the entire line is discarded as a comment.
-So lets look at a really simple job file that define to threads, each
+So let's look at a really simple job file that defines two processes, each
randomly reading from a 128MiB file.
; -- start job file --
$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
-Lets look at an example that have a number of processes writing randomly
+Let's look at an example that has a number of processes writing randomly
to files.
; -- start job file --
$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
+fio also supports environment variable expansion in job files. Any
+substring of the form "${VARNAME}" as part of an option value (in other
+words, on the right of the `='), will be expanded to the value of the
+environment variable called VARNAME. If no such environment variable
+is defined, or VARNAME is the empty string, the empty string will be
+substituted.
+
+As an example, let's look at a sample fio invocation and job file:
+
+$ SIZE=64m NUMJOBS=4 fio jobfile.fio
+
+; -- start job file --
+[random-writers]
+rw=randwrite
+size=${SIZE}
+numjobs=${NUMJOBS}
+; -- end job file --
+
+This will expand to the following equivalent job file at runtime:
+
+; -- start job file --
+[random-writers]
+rw=randwrite
+size=64m
+numjobs=4
+; -- end job file --
+
fio ships with a few example job files, you can also look there for
inspiration.
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.
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.
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
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
+write_bw_log=str If given, write a bandwidth log of the jobs in this job
file. Can be used to store data of the bandwidth of the
jobs in their lifetime. The included fio_generate_plots
script uses gnuplot to turn these text files into nice
- graphs.
+ graphs. See write_log_log for behaviour of given
+ filename. For this option, the postfix is _bw.log.
+
+write_lat_log=str Same as write_bw_log, except that this option stores io
+ completion latencies instead. If no filename is given
+ with this option, the default filename of "jobname_type.log"
+ is used. Even if the filename is given, fio will still
+ append the type of log. So if one specifies
-write_lat_log Same as write_bw_log, except that this option stores io
- completion latencies instead.
+ write_lat_log=foo
+
+ 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
potentially be used instead of removing memory or booting
disk_util=bool Generate disk utilization statistics, if the platform
supports it. Defaults to on.
+disable_clat=bool Disable measurements of completion latency numbers. Useful
+ only for cutting back the number of calls to gettimeofday,
+ as that does impact performance at really high IOPS rates.
+ Note that to really get rid of a large amount of these
+ calls, this option must be used with disable_slat and
+ disable_bw as well.
+
+disable_slat=bool Disable measurements of submission latency numbers. See
+ disable_clat.
+
+disable_bw=bool Disable measurements of throughput/bandwidth numbers. See
+ disable_clat.
+
+gtod_reduce=bool Enable all of the gettimeofday() reducing options
+ (disable_clat, disable_slat, disable_bw) plus reduce
+ precision of the timeout somewhat to really shrink
+ the gettimeofday() call count. With this option enabled,
+ 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