Document loading external io engines

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/HOWTO b/HOWTO
index de4b0a9932b43f207260a569a5e33349efebc63b..745e9c72906a378fe1c5fb3818b3ab139834d633 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -289,6 +289,11 @@ ioengine=str       Defines how the job issues io to the file. The following
                                or receive, if the latter only the port
                                argument is used.
 
+                       external Prefix to specify loading an external
+                               IO engine object file. Append the engine
+                               filename, eg ioengine=external:/tmp/foo.o
+                               to load ioengine foo.o in /tmp.
+
 iodepth=int    This defines how many io units to keep in flight against
                the file. The default is 1 for each file defined in this
                job, can be overridden with a larger value for higher