docs: update cmdprio_percentage with note about root user

The io_uring/libaio cmdprio_percentage option can only be used when fio
is run from the root user account because IOs are submitted with IO
priority class IOPRIO_CLASS_RT. Note in the documentation that fio must
be run from the root account to use this option.

Signed-off-by: Vincent Fu <vincent.fu@wdc.com>

diff --git a/HOWTO b/HOWTO
index 430c7b62bff8e28c40065cb8ac877579c2325a99..cd6285524f392c0a911a2e133dd3d4b6b40aa371 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -2040,7 +2040,8 @@ with the caveat that when used on the command line, they must come after the
     the priority bit. Non-read I/O is likely unaffected by ``cmdprio_percentage``.
     This option cannot be used with the `prio` or `prioclass` options. For this
     option to set the priority bit properly, NCQ priority must be supported and
-    enabled and :option:`direct`\=1 option must be used.
+    enabled and :option:`direct`\=1 option must be used. fio must also be run as
+    the root user.
 
 .. option:: fixedbufs : [io_uring]
 

diff --git a/fio.1 b/fio.1
index a2379f9816c2b0103191ff15338d9180527bf896..9e9e1b1adcd46ea5fb42ded350e6b0ce4ef65ea0 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -1806,7 +1806,8 @@ Set the percentage of I/O that will be issued with higher priority by setting
 the priority bit. Non-read I/O is likely unaffected by ``cmdprio_percentage``.
 This option cannot be used with the `prio` or `prioclass` options. For this
 option to set the priority bit properly, NCQ priority must be supported and
-enabled and `direct=1' option must be used.
+enabled and `direct=1' option must be used. fio must also be run as the root
+user.
 .TP
 .BI (io_uring)fixedbufs
 If fio is asked to do direct IO, then Linux will map pages for each IO call, and