Add terse version output format command line parameter

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index a1b2e8c0bf7a6f51bceb8016618acb32e7dae01e..724b604b19c1116b87f32cc4b385e36e92dcd445 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -517,6 +517,16 @@ ioengine=str       Defines how the job issues io to the file. The following
                        libaio  Linux native asynchronous io. Note that Linux
                                may only support queued behaviour with
                                non-buffered IO (set direct=1 or buffered=0).
+                               This engine also has a sub-option,
+                               userspace_reap. To set it, use
+                               ioengine=libaio:userspace_reap. Normally, with
+                               the libaio engine in use, fio will use the
+                               io_getevents system call to reap newly returned
+                               events. With this flag turned on, the AIO ring
+                               will be read directly from user-space to reap
+                               events. The reaping mode is only enabled when
+                               polling for a minimum of 0 events (eg when
+                               iodepth_batch_complete=0).
 
                        posixaio glibc posix asynchronous io.