linux-kernel - [PATCH v3 3/3] perf mem: Support HITM for when mem_lvl

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Message-ID: <20220318195913.17459-4-alisaidi@amazon.com>
Date:   Fri, 18 Mar 2022 19:59:13 +0000
From:   Ali Saidi <alisaidi@...zon.com>
To:     <linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <german.gomez@....com>,
        <leo.yan@...aro.org>
CC:     <alisaidi@...zon.com>, <benh@...nel.crashing.org>,
        <Nick.Forrington@....com>, <acme@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <andrew.kilroy@....com>,
        <james.clark@....com>, <john.garry@...wei.com>, <jolsa@...nel.org>,
        <kjain@...ux.ibm.com>, <lihuafei1@...wei.com>,
        <mark.rutland@....com>, <mathieu.poirier@...aro.org>,
        <mingo@...hat.com>, <namhyung@...nel.org>, <peterz@...radead.org>,
        <will@...nel.org>
Subject: [PATCH v3 3/3] perf mem: Support HITM for when mem_lvl_num is any

For loads that hit in a the LLC snoop filter and are fulfilled from a
higher level cache on arm64 Neoverse cores, it's not usually clear what
the true level of the cache the data came from (i.e. a transfer from a
core could come from it's L1 or L2). Instead of making an assumption of
where the line came from, add support for incrementing HITM if the
source is CACHE_ANY.

Since other architectures don't seem to populate the mem_lvl_num field
here there shouldn't be a change in functionality.

Signed-off-by: Ali Saidi <alisaidi@...zon.com>
---
 tools/perf/util/mem-events.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
index e5e405185498..084977cfebef 100644
--- a/tools/perf/util/mem-events.c
+++ b/tools/perf/util/mem-events.c
@@ -539,6 +539,15 @@ do {				\
 					stats->ld_llchit++;
 			}
 
+			/*
+			 * A hit in another cores cache must mean a llc snoop
+			 * filter hit
+			 */
+			if (lnum == P(LVLNUM, ANY_CACHE)) {
+				if (snoop & P(SNOOP, HITM))
+					HITM_INC(lcl_hitm);
+			}
+
 			if (lvl & P(LVL, LOC_RAM) || lnum == P(LVLNUM, RAM)) {
 				stats->lcl_dram++;
 				if (snoop & P(SNOOP, HIT))
-- 
2.32.0