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From:   Ali Saidi <alisaidi@amazon.com>
To:     <linux-kernel@vger.kernel.org>, <linux-perf-users@vger.kernel.org>,
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Subject: [PATCH v5 2/5] perf: Add SNOOP_PEER flag to perf mem data struct
Date:   Fri, 8 Apr 2022 19:53:41 +0000
Message-ID: <20220408195344.32764-3-alisaidi@amazon.com>
In-Reply-To: <20220408195344.32764-1-alisaidi@amazon.com>
References: <20220408195344.32764-1-alisaidi@amazon.com>
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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@amazon.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 82858b697c05..c9e58c79f3e5 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -1308,7 +1308,7 @@ 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 */
-- 
2.32.0