Thread (6 messages) 6 messages, 3 authors, 2022-03-22
STALE1561d
Revisions (7)
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  6. v8 [diff vs current]
  7. v8 [diff vs current]

[PATCH v3 3/3] perf mem: Support HITM for when mem_lvl_num is any

From: Ali Saidi <hidden>
Date: 2022-03-18 19:59:38
Also in: linux-perf-users, lkml
Subsystem: performance events subsystem, the rest · Maintainers: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds

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 <redacted>
---
 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


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