docs: enable serialize_overlap with io_submit_mode=offload

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index a2503e9a6b73b093aee91c65ba2255f9cc690746..72ef8725818c91105be33fe44568ed3e55558b59 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -2339,8 +2339,13 @@ I/O depth
        ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
        serializing in-flight I/Os that have a non-zero overlap. Note that setting
        this option can reduce both performance and the :option:`iodepth` achieved.
-       Additionally this option does not work when :option:`io_submit_mode` is set to
-       offload. Default: false.
+
+       This option only applies to I/Os issued for a single job except when it is
+       enabled along with :option:`io_submit_mode`=offload. In offload mode, fio
+       will check for overlap among all I/Os submitted by offload jobs with :option:`serialize_overlap`
+       enabled. Threads must be used for all such jobs.
+
+       Default: false.
 
 .. option:: io_submit_mode=str