[PATCH v4 6/7] fs/resctrl: Document that automatic counter assignment is best effort

Ben Horgan
2026-03-26T17:26:13Z

When using automatic counter assignment it's useful for a user to know
which counters they can expect to be assigned on group creation.

Document that automatic counter assignment is best effort and how to
discover any assignment failures.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---

Hi Reinette,
I've just taken your suggested paragraph with a minor tweak (s/scenario/a
scenario/) and moved it above the examples as I think it makes sense to
keep examples last in each section.
---
Documentation/filesystems/resctrl.rst | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index ba609f8d4de5..68cada238844 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -472,6 +472,12 @@ with the following files:
"1":
Auto assignment is enabled.

+ Automatic counter assignment is done with best effort. If auto
+ assignment is enabled but there are not enough available counters then
+ monitor group creation could succeed while one or more events belonging
+ to the group may not have a counter assigned. Consult last_cmd_status
+ for details during such a scenario.
+
Example::

# echo 0 > /sys/fs/resctrl/info/L3_MON/mbm_assign_on_mkdir
--
2.43.0