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

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 297a04851a2bbb747d9c3b8e6df0143be45203a2..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
-    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]
 
@@ -3538,6 +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:: 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