Set the maximum number of threads/processes to support to `nr`.
NOTE: On Linux, it may be necessary to increase the shared-memory
- limit ('/proc/sys/kernel/shmmax') if fio runs into errors while
+ limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
creating jobs.
.. option:: --server=args
.. option:: --client=hostname
Instead of running the jobs locally, send and run them on the given `hostname`
- or set of `hostname`s. See `Client/Server`_ section.
+ or set of `hostname`\s. See `Client/Server`_ section.
.. option:: --remote-config=file
named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
will be used if no other format specifier is given.
+ If you specify a path then the directories will be created up to the
+ main directory for the file. So for example if you specify
+ ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
+ created before the file setup part of the job. If you specify
+ :option:`directory` then the path will be relative that directory,
+ otherwise it is treated as the absolute path.
+
.. option:: unique_filename=bool
To avoid collisions between networked clients, fio defaults to prefixing any
.. option:: offset=int
Start I/O at the provided offset in the file, given as either a fixed size in
- bytes or a percentage. If a percentage is given, the next ``blockalign``-ed
- offset will be used. Data before the given offset will not be touched. This
+ bytes or a percentage. If a percentage is given, the generated offset will be
+ aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
+ provided. Data before the given offset will not be touched. This
effectively caps the file size at `real_size - offset`. Can be combined with
:option:`size` to constrain the start and end range of the I/O workload.
A percentage can be specified by a number between 1 and 100 followed by '%',
for example, ``offset=20%`` to specify 20%.
+.. option:: offset_align=int
+
+ If set to non-zero value, the byte offset generated by a percentage ``offset``
+ is aligned upwards to this value. Defaults to 0 meaning that a percentage
+ offset is aligned to the minimum block size.
+
.. option:: offset_increment=int
If this is provided, then the real offset becomes `offset + offset_increment
Doesn't transfer any data, but burns CPU cycles according to the
:option:`cpuload` and :option:`cpuchunks` options. Setting
:option:`cpuload`\=85 will cause that job to do nothing but burn 85%
- of the CPU. In case of SMP machines, use :option:`numjobs`=<nr_of_cpu>
+ of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
to get desired CPU usage, as the cpuload only loads a
single CPU at the desired rate. A job never finishes unless there is
at least one non-cpuio job.
details of writing an external I/O engine.
**filecreate**
- Simply create the files and do no IO to them. You still need to
+ Simply create the files and do no I/O to them. You still need to
set `filesize` so that all the accounting still occurs, but no
- actual IO will be done other than creating the file.
+ actual I/O will be done other than creating the file.
I/O engine specific parameters
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
changing data and the overlapping region has a non-zero size. Setting
``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
serializing in-flight I/Os that have a non-zero overlap. Note that setting
- this option can reduce both performance and the `:option:iodepth` achieved.
+ this option can reduce both performance and the :option:`iodepth` achieved.
Additionally this option does not work when :option:`io_submit_mode` is set to
offload. Default: false.
.. option:: lat_percentiles=bool
- Enable the reporting of percentiles of IO latencies. This is similar
+ Enable the reporting of percentiles of I/O latencies. This is similar
to :option:`clat_percentiles`, except that this includes the
submission latency. This option is mutually exclusive with
:option:`clat_percentiles`.
short or dropped.
**IO latency**
- These values are for `--latency-target` and related options. When
+ These values are for :option:`latency_target` and related options. When
these options are engaged, this section describes the I/O depth required
to meet the specified latency target.