linux-kernel - [PATCH v3 2/4] perf: Add mem_hops field in perf_mem_data

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Date:   Wed,  6 Oct 2021 19:36:52 +0530
From:   Kajol Jain <kjain@...ux.ibm.com>
To:     mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org, jolsa@...nel.org,
        namhyung@...nel.org, ak@...ux.intel.com
Cc:     linux-perf-users@...r.kernel.org, maddy@...ux.ibm.com,
        atrajeev@...ux.vnet.ibm.com, rnsastry@...ux.ibm.com,
        yao.jin@...ux.intel.com, ast@...nel.org, daniel@...earbox.net,
        songliubraving@...com, kan.liang@...ux.intel.com,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        paulus@...ba.org, kjain@...ux.ibm.com
Subject: [PATCH v3 2/4] perf: Add mem_hops field in perf_mem_data_src structure

Going forward, future generation systems can have more hierarchy
within the node/package level but currently we don't have any data source
encoding field in perf, which can be used to represent this level of data.

Add a new field called 'mem_hops' in the perf_mem_data_src structure
which can be used to represent intra-node/package or inter-node/off-package
details. This field is of size 3 bits where PERF_MEM_HOPS_{NA, 0..6} value
can be used to present different hop levels data.

Also add corresponding macros to define mem_hop field values
and shift value.

Currently we define macro for HOPS_0 which corresponds
to data coming from another core but same node.

For ex: Encodings for mem_hops fields with L2 cache:

L2			- local L2
L2 | REMOTE | HOPS_0	- remote core, same node L2

Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
---
 include/uapi/linux/perf_event.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index e1701e9c7858..2fc09579e24a 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -1210,14 +1210,16 @@ union perf_mem_data_src {
 			mem_remote:1,   /* remote */
 			mem_snoopx:2,	/* snoop mode, ext */
 			mem_blk:3,	/* access blocked */
-			mem_rsvd:21;
+			mem_hops:3,	/* hop level */
+			mem_rsvd:18;
 	};
 };
 #elif defined(__BIG_ENDIAN_BITFIELD)
 union perf_mem_data_src {
 	__u64 val;
 	struct {
-		__u64	mem_rsvd:21,
+		__u64	mem_rsvd:18,
+			mem_hops:3,	/* hop level */
 			mem_blk:3,	/* access blocked */
 			mem_snoopx:2,	/* snoop mode, ext */
 			mem_remote:1,   /* remote */
@@ -1313,6 +1315,11 @@ union perf_mem_data_src {
 #define PERF_MEM_BLK_ADDR	0x04 /* address conflict */
 #define PERF_MEM_BLK_SHIFT	40
 
+/* hop level */
+#define PERF_MEM_HOPS_0		0x01 /* remote core, same node */
+/* 2-7 available */
+#define PERF_MEM_HOPS_SHIFT	43
+
 #define PERF_MEM_S(a, s) \
 	(((__u64)PERF_MEM_##a##_##s) << PERF_MEM_##a##_SHIFT)
 
-- 
2.26.2