Merge branch 'testing' of https://github.com/vincentkfu/fio

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index f19f9226a93de504d04aad6c60c27856bf1b19cb..9e71a6197bb47000db195fcdc5e09cc0f70b2d51 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -2040,7 +2040,8 @@ with the caveat that when used on the command line, they must come after the
     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]
 
@@ -2261,9 +2262,10 @@ with the caveat that when used on the command line, they must come after the
        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]
 
@@ -2550,6 +2552,13 @@ I/O latency
        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
@@ -3346,27 +3355,28 @@ Measurements and reporting
        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