Avoid client calls to recv() without prior poll()

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 1853f56ad78ae89a7cc263724bd739cc40c14f27..8c9e41356b9586b33fa17e4068d50620eb6be551 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -2167,10 +2167,13 @@ with the caveat that when used on the command line, they must come after the
 
     Set the percentage of I/O that will be issued with the highest priority.
     Default: 0. A single value applies to reads and writes. Comma-separated
 
     Set the percentage of I/O that will be issued with the highest priority.
     Default: 0. A single value applies to reads and writes. Comma-separated

-    values may be specified for reads and writes. This option cannot be used
-    with the :option:`prio` or :option:`prioclass` options. For this option
-    to be effective, NCQ priority must be supported and enabled, and `direct=1'
-    option must be used. fio must also be run as the root user.
+    values may be specified for reads and writes. For this option to be
+    effective, NCQ priority must be supported and enabled, and `direct=1'
+    option must be used. fio must also be run as the root user. Unlike
+    slat/clat/lat stats, which can be tracked and reported independently, per
+    priority stats only track and report a single type of latency. By default,
+    completion latency (clat) will be reported, if :option:`lat_percentiles` is
+    set, total latency (lat) will be reported.

 
 .. option:: cmdprio_class=int[,int] : [io_uring] [libaio]
 
 
 .. option:: cmdprio_class=int[,int] : [io_uring] [libaio]
 


@@ -2745,7 +2748,7 @@ I/O rate
        Stall the job for the specified period of time after an I/O has completed before issuing the
        next. May be used to simulate processing being done by an application.
        When the unit is omitted, the value is interpreted in microseconds.  See
        Stall the job for the specified period of time after an I/O has completed before issuing the
        next. May be used to simulate processing being done by an application.
        When the unit is omitted, the value is interpreted in microseconds.  See

-       :option:`thinktime_blocks` and :option:`thinktime_spin`.
+       :option:`thinktime_blocks`, :option:`thinktime_iotime` and :option:`thinktime_spin`.

 
 .. option:: thinktime_spin=time
 
 
 .. option:: thinktime_spin=time
 


@@ -2770,6 +2773,18 @@ I/O rate
        :option:`thinktime_blocks` blocks. If this is set to `issue`, then the trigger happens
        at the issue side.
 
        :option:`thinktime_blocks` blocks. If this is set to `issue`, then the trigger happens
        at the issue side.
 

+.. option:: thinktime_iotime=time
+
+       Only valid if :option:`thinktime` is set - control :option:`thinktime`
+       interval by time. The :option:`thinktime` stall is repeated after IOs
+       are executed for :option:`thinktime_iotime`. For example,
+       ``--thinktime_iotime=9s --thinktime=1s`` repeat 10-second cycle with IOs
+       for 9 seconds and stall for 1 second. When the unit is omitted,
+       :option:`thinktime_iotime` is interpreted as a number of seconds. If
+       this option is used together with :option:`thinktime_blocks`, the
+       :option:`thinktime` stall is repeated after :option:`thinktime_iotime`
+       or after :option:`thinktime_blocks` IOs, whichever happens first.
+

 .. option:: rate=int[,int][,int]
 
        Cap the bandwidth used by this job. The number is in bytes/sec, the normal
 .. option:: rate=int[,int][,int]
 
        Cap the bandwidth used by this job. The number is in bytes/sec, the normal


@@ -3526,6 +3541,18 @@ Measurements and reporting
        :option:`write_bw_log` for details about the filename format and `Log
        File Formats`_ for how data is structured within the file.
 
        :option:`write_bw_log` for details about the filename format and `Log
        File Formats`_ for how data is structured within the file.
 

+.. option:: log_entries=int
+
+       By default, fio will log an entry in the iops, latency, or bw log for
+       every I/O that completes. The initial number of I/O log entries is 1024.
+       When the log entries are all used, new log entries are dynamically
+       allocated.  This dynamic log entry allocation may negatively impact
+       time-related statistics such as I/O tail latencies (e.g. 99.9th percentile
+       completion latency). This option allows specifying a larger initial
+       number of log entries to avoid run-time allocations of new log entries,
+       resulting in more precise time-related I/O statistics.
+       Also see :option:`log_avg_msec`. Defaults to 1024.
+

 .. option:: log_avg_msec=int
 
        By default, fio will log an entry in the iops, latency, or bw log for every
 .. option:: log_avg_msec=int
 
        By default, fio will log an entry in the iops, latency, or bw log for every