may override any parameter set in global sections.
.SH "JOB PARAMETERS"
.SS Types
-Some parameters may take arguments of a specific type. The types used are:
+Some parameters may take arguments of a specific type.
+Anywhere a numeric value is required, an arithmetic expression may be used,
+provided it is surrounded by parentheses. Supported operators are:
+.RS
+.RS
+.TP
+.B addition (+)
+.TP
+.B subtraction (-)
+.TP
+.B multiplication (*)
+.TP
+.B division (/)
+.TP
+.B modulus (%)
+.TP
+.B exponentiation (^)
+.RE
+.RE
+.P
+For time values in expressions, units are microseconds by default. This is
+different than for time values not in expressions (not enclosed in
+parentheses). The types used are:
.TP
.I str
String: a sequence of alphanumeric characters.
device, \\.\PhysicalDrive1 for the second etc. Note: Windows and FreeBSD
prevent write access to areas of the disk containing in-use data
(e.g. filesystems). If the wanted filename does need to include a colon, then
-escape that with a '\' character. For instance, if the filename is
-"/dev/dsk/foo@3,0:c", then you would use filename="/dev/dsk/foo@3,0\:c".
+escape that with a '\\' character. For instance, if the filename is
+"/dev/dsk/foo@3,0:c", then you would use filename="/dev/dsk/foo@3,0\\:c".
.TP
.BI filename_format \fR=\fPstr
If sharing multiple files between jobs, it is usually necessary to have
divided between the available files for the job. If not set, fio will use the
full size of the given files or devices. If the files do not exist, size
must be given. It is also possible to give size as a percentage between 1 and
-100. If size=20% is given, fio will use 20% of the full size of the given files
-or devices.
+100. If size=20% is given, fio will use 20% of the full size of the given
+files or devices.
+.TP
+.BI io_limit \fR=\fPint
+Normally fio operates within the region set by \fBsize\fR, which means that
+the \fBsize\fR option sets both the region and size of IO to be performed.
+Sometimes that is not what you want. With this option, it is possible to
+define just the amount of IO that fio should do. For instance, if \fBsize\fR
+is set to 20G and \fBio_limit\fR is set to 5G, fio will perform IO within
+the first 20G but exit when 5G have been done.
.TP
.BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
Sets size to something really large and waits for ENOSPC (no space left on
If set, fio will fill the IO buffers with this pattern. If not set, the contents
of IO buffers is defined by the other options related to buffer contents. The
setting can be any pattern of bytes, and can be prefixed with 0x for hex
-values.
+values. It may also be a string, where the string must then be wrapped with
+"".
+.TP
+.BI dedupe_percentage \fR=\fPint
+If set, fio will generate this percentage of identical buffers when writing.
+These buffers will be naturally dedupable. The contents of the buffers depend
+on what other buffer compression settings have been set. It's possible to have
+the individual buffers either fully compressible, or not at all. This option
+only controls the distribution of unique buffers.
.TP
.BI nrfiles \fR=\fPint
Number of files to use for this job. Default: 1.
IO engine supporting direct access to Ceph Rados Block Devices (RBD) via librbd
without the need to use the kernel rbd driver. This ioengine defines engine specific
options.
+.TP
+.B gfapi
+Using Glusterfs libgfapi sync interface to direct access to Glusterfs volumes without
+having to go through FUSE. This ioengine defines engine specific
+options.
+.TP
+.B gfapi_async
+Using Glusterfs libgfapi async interface to direct access to Glusterfs volumes without
+having to go through FUSE. This ioengine defines engine specific
+options.
+.TP
+.B libhdfs
+Read and write through Hadoop (HDFS). The \fBfilename\fR option is used to
+specify host,port of the hdfs name-node to connect. This engine interprets
+offsets a little differently. In HDFS, files once created cannot be modified.
+So random writes are not possible. To imitate this, libhdfs engine expects
+bunch of small files to be created over HDFS, and engine will randomly pick a
+file out of those files based on the offset generated by fio backend. (see the
+example job file to create such files, use rw=write option). Please note, you
+might want to set necessary environment variables to work with hdfs/libhdfs
+properly.
.RE
.P
.RE
.TP
.BI offset_increment \fR=\fPint
If this is provided, then the real offset becomes the
-offset + offset_increment * thread_number, where the thread number is a counter
-that starts at 0 and is incremented for each job. This option is useful if
-there are several jobs which are intended to operate on a file in parallel in
-disjoint segments, with even spacing between the starting points.
+offset + offset_increment * thread_number, where the thread number is a
+counter that starts at 0 and is incremented for each sub-job (i.e. when
+numjobs option is specified). This option is useful if there are several jobs
+which are intended to operate on a file in parallel disjoint segments, with
+even spacing between the starting points.
.TP
.BI number_ios \fR=\fPint
Fio will normally perform IOs until it has exhausted the size of the region
set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
condition). With this setting, the range/size can be set independently of
the number of IOs to perform. When fio reaches this number, it will exit
-normally and report status.
+normally and report status. Note that this does not extend the amount
+of IO that will be done, it will only stop fio if this condition is met
+before other end-of-job criteria.
.TP
.BI fsync \fR=\fPint
How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
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. See \fBwrite_lat_log\fR for behaviour of given filename. For this
-option, the postfix is _bw.log.
+option, the postfix is _bw.x.log, where x is the index of the job (1..N,
+where N is the number of jobs)
.TP
.BI write_lat_log \fR=\fPstr
Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. 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.
+filename is given with this option, the default filename of
+"jobname_type.x.log" is used, where x is the index of the job (1..N, where
+N is the number of jobs). Even if the filename is given, fio will still
+append the type of log.
.TP
.BI write_iops_log \fR=\fPstr
Same as \fBwrite_bw_log\fR, but writes IOPS. 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.
+option, the default filename of "jobname_type.x.log" is used, where x is the
+index of the job (1..N, where N is the number of jobs). Even if the filename
+is given, fio will still append the type of log.
.TP
.BI log_avg_msec \fR=\fPint
By default, fio will log an entry in the iops, latency, or bw log for every
over the specified period of time, reducing the resolution of the log.
Defaults to 0.
.TP
+.BI log_offset \fR=\fPbool
+If this is set, the iolog options will include the byte offset for the IO
+entry as well as the other data values.
+.TP
+.BI log_compression \fR=\fPint
+If this is set, fio will compress the IO logs as it goes, to keep the memory
+footprint lower. When a log reaches the specified size, that chunk is removed
+and compressed in the background. Given that IO logs are fairly highly
+compressible, this yields a nice memory savings for longer runs. The downside
+is that the compression will consume some background CPU cycles, so it may
+impact the run. This, however, is also true if the logging ends up consuming
+most of the system memory. So pick your poison. The IO logs are saved
+normally at the end of a run, by decompressing the chunks and storing them
+in the specified log file. This feature depends on the availability of zlib.
+.TP
+.BI log_store_compressed \fR=\fPbool
+If set, and \fBlog\fR_compression is also set, fio will store the log files in
+a compressed format. They can be decompressed with fio, using the
+\fB\-\-inflate-log\fR command line parameter. The files will be stored with a
+\fB\.fz\fR suffix.
+.TP
.BI disable_lat \fR=\fPbool
Disable measurements of total latency numbers. Useful only for cutting
back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
.BI ioscheduler \fR=\fPstr
Attempt to switch the device hosting the file to the specified I/O scheduler.
.TP
-.BI cpuload \fR=\fPint
-If the job is a CPU cycle-eater, attempt to use the specified percentage of
-CPU cycles.
-.TP
-.BI cpuchunks \fR=\fPint
-If the job is a CPU cycle-eater, split the load into cycles of the
-given time in milliseconds.
-.TP
.BI disk_util \fR=\fPbool
Generate disk utilization statistics if the platform supports it. Default: true.
.TP
.BI (cpu)cpuchunks \fR=\fPint
Split the load into cycles of the given time. In microseconds.
.TP
+.BI (cpu)exit_on_io_done \fR=\fPbool
+Detect when IO threads are done, then exit.
+.TP
.BI (libaio)userspace_reap
Normally, with the libaio engine in use, fio will use
the io_getevents system call to reap newly returned events.
projects / fio.git / blobdiff