linux-kernel - [PATCH 6/7] x86/resctrl: Update documentation with Sub-NUMA cluster changes

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Message-Id: <20230126184157.27626-7-tony.luck@intel.com>
Date:   Thu, 26 Jan 2023 10:41:56 -0800
From:   Tony Luck <tony.luck@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>, x86@...nel.org
Cc:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, patches@...ts.linux.dev,
        Tony Luck <tony.luck@...el.com>
Subject: [PATCH 6/7] x86/resctrl: Update documentation with Sub-NUMA cluster changes

With Sub-NUMA Cluster mode enabled the scope of monitoring resources is
per-NODE instead of per-L3 cache. Suffices of directories with "L3" in
their name refer to Sun-NUMA nodes instead of L3 cache ids.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 Documentation/x86/resctrl.rst | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
index 71a531061e4e..9043a2d2f2d3 100644
--- a/Documentation/x86/resctrl.rst
+++ b/Documentation/x86/resctrl.rst
@@ -167,6 +167,11 @@ with the following files:
 		bytes) at which a previously used LLC_occupancy
 		counter can be considered for re-use.
 
+"snc_ways":
+                A value of "1" marks that SNC mode is disabled.
+                Values of "2" or "4" indicate how many NUMA
+                nodes share an L3 cache.
+
 Finally, in the top level of the "info" directory there is a file
 named "last_cmd_status". This is reset with every "command" issued
 via the file system (making new directories or writing to any of the
@@ -254,9 +259,13 @@ When control is enabled all CTRL_MON groups will also contain:
 When monitoring is enabled all MON groups will also contain:
 
 "mon_data":
-	This contains a set of files organized by L3 domain and by
-	RDT event. E.g. on a system with two L3 domains there will
-	be subdirectories "mon_L3_00" and "mon_L3_01".	Each of these
+	This contains a set of files organized by L3 domain or by NUMA
+	node (depending on whether SNC mode is disabled or enabled
+	respectively) and by RDT event. E.g. on a system with SNC
+	mode disabled with two L3 domains there will be subdirectories
+	"mon_L3_00" and "mon_L3_01" the numerical suffix refers to the
+        L3 cache id.  With SNC enabled the directory names are the same,
+        but the numerical suffix refers to the node id.  Each of these
 	directories have one file per event (e.g. "llc_occupancy",
 	"mbm_total_bytes", and "mbm_local_bytes"). In a MON group these
 	files provide a read out of the current value of the event for
-- 
2.39.1