linux-kernel - [PATCH v5 01/17] perf: Add SNOOP_PEER flag to perf mem data struct

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Message-Id: <20220604042820.2270916-2-leo.yan@linaro.org>
Date:   Sat,  4 Jun 2022 12:28:04 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        James Clark <james.clark@....com>,
        German Gomez <german.gomez@....com>,
        Ali Saidi <alisaidi@...zon.com>, Joe Mario <jmario@...hat.com>,
        Adam Li <adam.li@...erecomputing.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Leo Yan <leo.yan@...aro.org>, Kajol Jain <kjain@...ux.ibm.com>
Subject: [PATCH v5 01/17] perf: Add SNOOP_PEER flag to perf mem data struct

From: Ali Saidi <alisaidi@...zon.com>

Add a flag to the perf mem data struct to signal that a request caused a
cache-to-cache transfer of a line from a peer of the requestor and
wasn't sourced from a lower cache level.  The line being moved from one
peer cache to another has latency and performance implications. On Arm64
Neoverse systems the data source can indicate a cache-to-cache transfer
but not if the line is dirty or clean, so instead of overloading HITM
define a new flag that indicates this type of transfer.

Signed-off-by: Ali Saidi <alisaidi@...zon.com>
Reviewed-by: Leo Yan <leo.yan@...aro.org>
Reviewed-by: Kajol Jain<kjain@...ux.ibm.com>
---
 include/uapi/linux/perf_event.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index d37629dbad72..7b88bfd097dc 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -1310,7 +1310,7 @@ union perf_mem_data_src {
 #define PERF_MEM_SNOOP_SHIFT	19
 
 #define PERF_MEM_SNOOPX_FWD	0x01 /* forward */
-/* 1 free */
+#define PERF_MEM_SNOOPX_PEER	0x02 /* xfer from peer */
 #define PERF_MEM_SNOOPX_SHIFT  38
 
 /* locked instruction */
-- 
2.25.1