engines/libblkio: Add option libblkio_force_enable_completion_eventfd

[fio.git] / HOWTO.rst

diff --git a/HOWTO.rst b/HOWTO.rst
index e9602f59f648a3f095b1ee47c4f0f2d6822dff14..1cea16c4be5de8fafc4102f936bdeca4cd412d19 100644 (file)
--- a/HOWTO.rst
+++ b/HOWTO.rst
@@ -2338,7 +2338,8 @@ with the caveat that when used on the command line, they must come after the
    [libblkio]
 
        Use poll queues. This is incompatible with
-       :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>`.
+       :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>` and
+       :option:`libblkio_force_enable_completion_eventfd`.
 
    [pvsync2]
 
@@ -2907,6 +2908,12 @@ with the caveat that when used on the command line, they must come after the
        **loop**
                Use a busy loop with a non-blocking call to ``blkioq_do_io()``.
 
+.. option:: libblkio_force_enable_completion_eventfd : [libblkio]
+
+       Enable the queue's completion eventfd even when unused. This may impact
+       performance. The default is to enable it only if
+       :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>`.
+
 I/O depth
 ~~~~~~~~~