[tip: x86/cache] x86/resctrl: Document the new "mba_MBps_event" file

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     faf6ef673787956ec4d33ac8bf56f8ea929abf37
Gitweb:        https://git.kernel.org/tip/faf6ef673787956ec4d33ac8bf56f8ea929abf37
Author:        Tony Luck <tony.luck@xxxxxxxxx>
AuthorDate:    Fri, 06 Dec 2024 08:31:48 -08:00
Committer:     Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Thu, 12 Dec 2024 11:27:43 +01:00

x86/resctrl: Document the new "mba_MBps_event" file

Add a section to document a new read/write file that shows/sets the memory
bandwidth event used to control bandwidth used by each CTRL_MON group.

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Link: https://lore.kernel.org/r/20241206163148.83828-9-tony.luck@xxxxxxxxx
---
 Documentation/arch/x86/resctrl.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index a824aff..6768fc1 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -384,6 +384,16 @@ When monitoring is enabled all MON groups will also contain:
 	Available only with debug option. The identifier used by hardware
 	for the monitor group. On x86 this is the RMID.
 
+When the "mba_MBps" mount option is used all CTRL_MON groups will also contain:
+
+"mba_MBps_event":
+	Reading this file shows which memory bandwidth event is used
+	as input to the software feedback loop that keeps memory bandwidth
+	below the value specified in the schemata file. Writing the
+	name of one of the supported memory bandwidth events found in
+	/sys/fs/resctrl/info/L3_MON/mon_features changes the input
+	event.
+
 Resource allocation rules
 -------------------------