linux-kernel - [PATCH v2 2/2] perf mem: Support HITM for when mem_lvl

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Message-ID: <20220221224807.18172-2-alisaidi@amazon.com>
Date:   Mon, 21 Feb 2022 22:48:00 +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>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        "Arnaldo Carvalho de Melo" <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "Alexander Shishkin" <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        John Garry <john.garry@...wei.com>,
        "Will Deacon" <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        "James Clark" <james.clark@....com>,
        Andrew Kilroy <andrew.kilroy@....com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Li Huafei <lihuafei1@...wei.com>
Subject: [PATCH v2 2/2] perf mem: Support HITM for when mem_lvl_num is used

Current code only support HITM statistics for last level cache (LLC)
when mem_lvl encodes the level. On existing Arm64 machines there are as
many as four levels cache and this change supports decoding l1, l2, and
llc hits from the mem_lvl_num data. Given that the mem_lvl namespace is
being deprecated take this opportunity to encode the neoverse data into
mem_lvl_num.

For loads that hit in a the LLC snoop filter and are fullfilled from a
higher level cache, 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 | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
index ed0ab838bcc5..6c3fd4aac7ae 100644
--- a/tools/perf/util/mem-events.c
+++ b/tools/perf/util/mem-events.c
@@ -485,6 +485,7 @@ int c2c_decode_stats(struct c2c_stats *stats, struct mem_info *mi)
 	u64 daddr  = mi->daddr.addr;
 	u64 op     = data_src->mem_op;
 	u64 lvl    = data_src->mem_lvl;
+	u64 lnum   = data_src->mem_lvl_num;
 	u64 snoop  = data_src->mem_snoop;
 	u64 lock   = data_src->mem_lock;
 	u64 blk    = data_src->mem_blk;
@@ -527,16 +528,18 @@ do {				\
 			if (lvl & P(LVL, UNC)) stats->ld_uncache++;
 			if (lvl & P(LVL, IO))  stats->ld_io++;
 			if (lvl & P(LVL, LFB)) stats->ld_fbhit++;
-			if (lvl & P(LVL, L1 )) stats->ld_l1hit++;
-			if (lvl & P(LVL, L2 )) stats->ld_l2hit++;
-			if (lvl & P(LVL, L3 )) {
+			if (lvl & P(LVL, L1) || lnum == P(LVLNUM, L1))
+				stats->ld_l1hit++;
+			if (lvl & P(LVL, L2) || lnum == P(LVLNUM, L2))
+				stats->ld_l2hit++;
+			if (lvl & P(LVL, L3) || lnum == P(LVLNUM, L4)) {
 				if (snoop & P(SNOOP, HITM))
 					HITM_INC(lcl_hitm);
 				else
 					stats->ld_llchit++;
 			}
 
-			if (lvl & P(LVL, LOC_RAM)) {
+			if (lvl & P(LVL, LOC_RAM) || lnum == P(LVLNUM, RAM)) {
 				stats->lcl_dram++;
 				if (snoop & P(SNOOP, HIT))
 					stats->ld_shared++;
@@ -564,6 +567,9 @@ do {				\
 				HITM_INC(rmt_hitm);
 		}
 
+		if (lnum == P(LVLNUM, ANY_CACHE) && snoop & P(SNOOP, HITM))
+			HITM_INC(lcl_hitm);
+
 		if ((lvl & P(LVL, MISS)))
 			stats->ld_miss++;
 
-- 
2.32.0