set `filesize` so that all the accounting still occurs, but no
actual I/O will be done other than creating the file.
+ **filestat**
+ Simply do stat() and do no I/O to the file. You need to set 'filesize'
+ and 'nrfiles', so that files will be created.
+ This engine is to measure file lookup and meta data access.
+
**libpmem**
Read and write using mmap I/O to a file on a filesystem
mounted with DAX on a persistent memory device through the PMDK
with the caveat that when used on the command line, they must come after the
:option:`ioengine` that defines them is selected.
-.. option:: hipri : [io_uring]
+.. option:: cmdprio_percentage=int : [io_uring] [libaio]
- If this option is set, fio will attempt to use polled IO completions.
- Normal IO completions generate interrupts to signal the completion of
- IO, polled completions do not. Hence they are require active reaping
- by the application. The benefits are more efficient IO for high IOPS
- scenarios, and lower latencies for low queue depth IO.
+ Set the percentage of I/O that will be issued with higher priority by setting
+ the priority bit. Non-read I/O is likely unaffected by ``cmdprio_percentage``.
+ This option cannot be used with the `prio` or `prioclass` options. For this
+ option to set the priority bit properly, NCQ priority must be supported and
+ enabled and :option:`direct`\=1 option must be used. fio must also be run as
+ the root user.
.. option:: fixedbufs : [io_uring]
- If fio is asked to do direct IO, then Linux will map pages for each
- IO call, and release them when IO is done. If this option is set, the
- pages are pre-mapped before IO is started. This eliminates the need to
- map and release for each IO. This is more efficient, and reduces the
- IO latency as well.
+ If fio is asked to do direct IO, then Linux will map pages for each
+ IO call, and release them when IO is done. If this option is set, the
+ pages are pre-mapped before IO is started. This eliminates the need to
+ map and release for each IO. This is more efficient, and reduces the
+ IO latency as well.
+
+.. option:: hipri : [io_uring]
+
+ If this option is set, fio will attempt to use polled IO completions.
+ Normal IO completions generate interrupts to signal the completion of
+ IO, polled completions do not. Hence they are require active reaping
+ by the application. The benefits are more efficient IO for high IOPS
+ scenarios, and lower latencies for low queue depth IO.
.. option:: registerfiles : [io_uring]
+
With this option, fio registers the set of files being used with the
kernel. This avoids the overhead of managing file counts in the kernel,
making the submission and completion part more lightweight. Required
multiple paths exist between the client and the server or in certain loopback
configurations.
+.. option:: stat_type=str : [filestat]
+
+ Specify stat system call type to measure lookup/getattr performance.
+ Default is **stat** for :manpage:`stat(2)`.
+
.. option:: readfua=bool : [sg]
With readfua option set to 1, read operations include
defaults to 100.0, meaning that all I/Os must be equal or below to the value
set by :option:`latency_target`.
+.. option:: latency_run=bool
+
+ Used with :option:`latency_target`. If false (default), fio will find
+ the highest queue depth that meets :option:`latency_target` and exit. If
+ true, fio will continue running and try to meet :option:`latency_target`
+ by adjusting queue depth.
+
.. option:: max_latency=time
If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
Set the I/O priority value of this job. Linux limits us to a positive value
between 0 and 7, with 0 being the highest. See man
:manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
- systems since meaning of priority may differ.
+ systems since meaning of priority may differ. For per-command priority
+ setting, see I/O engine specific `cmdprio_percentage` and `hipri_percentage`
+ options.
.. option:: prioclass=int
- Set the I/O priority class. See man :manpage:`ionice(1)`.
+ Set the I/O priority class. See man :manpage:`ionice(1)`. For per-command
+ priority setting, see I/O engine specific `cmdprio_percentage` and
+ `hipri_percentage` options.
.. option:: cpus_allowed=str
Disable measurements of throughput/bandwidth numbers. See
:option:`disable_lat`.
+.. option:: slat_percentiles=bool
+
+ Report submission latency percentiles. Submission latency is not recorded
+ for synchronous ioengines.
+
.. option:: clat_percentiles=bool
- Enable the reporting of percentiles of completion latencies. This
- option is mutually exclusive with :option:`lat_percentiles`.
+ Report completion latency percentiles.
.. option:: lat_percentiles=bool
- 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`.
+ Report total latency percentiles. Total latency is the sum of submission
+ latency and completion latency.
.. option:: percentile_list=float_list
- Overwrite the default list of percentiles for completion latencies and
- the block error histogram. Each number is a floating number in the
- range (0,100], and the maximum length of the list is 20. Use ``:`` to
- separate the numbers, and list the numbers in ascending order. For
+ Overwrite the default list of percentiles for latencies and the block error
+ histogram. Each number is a floating point number in the range (0,100], and
+ the maximum length of the list is 20. Use ``:`` to separate the numbers. For
example, ``--percentile_list=99.5:99.9`` will cause fio to report the
- values of completion latency below which 99.5% and 99.9% of the observed
- latencies fell, respectively.
+ latency durations below which 99.5% and 99.9% of the observed latencies fell,
+ respectively.
.. option:: significant_figures=int
$ fio --read_iolog="<file1>:<file2>" --merge_blktrace_file="<output_file>"
Creating only the merged file can be done by passing the command line argument
-:option:`merge-blktrace-only`.
+:option:`--merge-blktrace-only`.
Scaling traces can be done to see the relative impact of any particular trace
being slowed down or sped up. :option:`merge_blktrace_scalars` takes in a colon
projects / fio.git / blobdiff