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.
+ enabled and :option:`direct`\=1 option must be used. fio must also be run as
+ the root user.
.. option:: fixedbufs : [io_uring]
When hipri is set this determines the probability of a pvsync2 I/O being high
priority. The default is 100%.
+.. option:: nowait : [pvsync2] [libaio] [io_uring]
+
+ By default if a request cannot be executed immediately (e.g. resource starvation,
+ waiting on locks) it is queued and the initiating process will be blocked until
+ the required resource becomes free.
+
+ This option sets the RWF_NOWAIT flag (supported from the 4.14 Linux kernel) and
+ the call will return instantly with EAGAIN or a partial result rather than waiting.
+
+ It is useful to also use ignore_error=EAGAIN when using this option.
+
+ Note: glibc 2.27, 2.28 have a bug in syscall wrappers preadv2, pwritev2.
+ They return EOPNOTSUP instead of EAGAIN.
+
+ For cached I/O, using this option usually means a request operates only with
+ cached data. Currently the RWF_NOWAIT flag does not supported for cached write.
+
+ For direct I/O, requests will only succeed if cache invalidation isn't required,
+ file blocks are fully allocated and the disk request could be issued immediately.
+
.. option:: cpuload=int : [cpuio]
Attempt to use the specified percentage of CPU cycles. This is a mandatory
multiple paths exist between the client and the server or in certain loopback
configurations.
-.. option:: lstat=bool : [filestat]
+.. option:: stat_type=str : [filestat]
- Use lstat(2) to measure lookup/getattr performance. Default is 0.
+ Specify stat system call type to measure lookup/getattr performance.
+ Default is **stat** for :manpage:`stat(2)`.
.. option:: readfua=bool : [sg]
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
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
and IOPS. The logs share a common format, which looks like this:
*time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
- *offset* (`bytes`)
+ *offset* (`bytes`), *command priority*
*Time* for the log entry is always in milliseconds. The *value* logged depends
on the type of log, it will be one of the following:
from the start of the file for that particular I/O. The logging of the offset can be
toggled with :option:`log_offset`.
+*Command priority* is 0 for normal priority and 1 for high priority. This is controlled
+by the ioengine specific :option:`cmdprio_percentage`.
+
Fio defaults to logging every individual I/O but when windowed logging is set
through :option:`log_avg_msec`, either the average (by default) or the maximum
(:option:`log_max_value` is set) *value* seen over the specified period of time
projects / fio.git / blobdiff