docs: enable serialize_overlap with io_submit_mode=offload

Note that it is now possible to enable overlap checking in offload
submission mode and that threads are required.

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
 

diff --git a/fio.1 b/fio.1
index bf181b345548414865d7d138ba38c372b1619941..7691b2b13daa7e489e109e43fd947e8834ca466d 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -2070,8 +2070,15 @@ changing data and the overlapping region has a non-zero size. Setting
 \fBserialize_overlap\fR 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 \fBiodepth\fR achieved.
-Additionally this option does not work when \fBio_submit_mode\fR is set to
-offload. Default: false.
+.RS
+.P
+This option only applies to I/Os issued for a single job except when it is
+enabled along with \fBio_submit_mode\fR=offload. In offload mode, fio
+will check for overlap among all I/Os submitted by offload jobs with \fBserialize_overlap\fR
+enabled. Threads must be used for all such jobs.
+.P
+Default: false.
+.RE
 .TP
 .BI io_submit_mode \fR=\fPstr
 This option controls how fio submits the I/O to the I/O engine. The default