Add sub-option support (sort-of) and convert libaio_userspace_reap
You should now use ioengine=libaio:userspace_reap instead of
the separate option.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fio.1 b/fio.1
index 488896c..ffc97c9 100644
--- a/fio.1
+++ b/fio.1
@@ -367,7 +367,13 @@
coalescing adjacents IOs into a single submission.
.TP
.B libaio
-Linux native asynchronous I/O.
+Linux native asynchronous I/O. This engine also has a sub-option,
+\fBuserspace_reap\fR. To set it, use \fBioengine=libaio:userspace_reap\fR.
+Normally, with the libaio engine in use, fio will use the
+\fIio_getevents\fR\|(3) 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 \fB0\fR
+events (eg when \fBiodepth_batch_complete=0\fR).
.TP
.B posixaio
POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).