linux-kernel - [PATCH v2] perf/x86/amd: Make HW_CACHE_REFERENCES and HW_CACHE

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Date:   Wed, 24 Aug 2016 14:12:08 +0100
From:   Matt Fleming <matt@...eblueprint.co.uk>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        stable@...r.kernel.org
Subject: [PATCH v2] perf/x86/amd: Make HW_CACHE_REFERENCES and HW_CACHE_MISSES measure L2

While the Intel PMU monitors the LLC when perf enables the
HW_CACHE_REFERENCES and HW_CACHE_MISSES events, these events monitor
L1 instruction cache fetches (0x0080) and instruction cache misses
(0x0081) on the AMD PMU.

This is extremely confusing when monitoring the same workload across
Intel and AMD machines, since parameters like,

  $ perf stat -e cache-references,cache-misses

measure completely different things.

Instead, make the AMD PMU measure instruction/data cache and TLB fill
requests to the L2 and instruction/data cache and TLB misses in the L2
when HW_CACHE_REFERENCES and HW_CACHE_MISSES are enabled,
respectively. That way the events measure unified caches on both
platforms.

Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: <stable@...r.kernel.org>
---

Changes in v2:
  - Update the KVM AMD PMU code
  - Also measure TLB hits/misses in the L2

 arch/x86/events/amd/core.c | 4 ++--
 arch/x86/kvm/pmu_amd.c     | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index e07a22bb9308..f5f4b3fbbbc2 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -119,8 +119,8 @@ static const u64 amd_perfmon_event_map[PERF_COUNT_HW_MAX] =
 {
   [PERF_COUNT_HW_CPU_CYCLES]			= 0x0076,
   [PERF_COUNT_HW_INSTRUCTIONS]			= 0x00c0,
-  [PERF_COUNT_HW_CACHE_REFERENCES]		= 0x0080,
-  [PERF_COUNT_HW_CACHE_MISSES]			= 0x0081,
+  [PERF_COUNT_HW_CACHE_REFERENCES]		= 0x077d,
+  [PERF_COUNT_HW_CACHE_MISSES]			= 0x077e,
   [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]		= 0x00c2,
   [PERF_COUNT_HW_BRANCH_MISSES]			= 0x00c3,
   [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= 0x00d0, /* "Decoder empty" event */
diff --git a/arch/x86/kvm/pmu_amd.c b/arch/x86/kvm/pmu_amd.c
index 39b91127ef07..cd944435dfbd 100644
--- a/arch/x86/kvm/pmu_amd.c
+++ b/arch/x86/kvm/pmu_amd.c
@@ -23,8 +23,8 @@
 static struct kvm_event_hw_type_mapping amd_event_mapping[] = {
 	[0] = { 0x76, 0x00, PERF_COUNT_HW_CPU_CYCLES },
 	[1] = { 0xc0, 0x00, PERF_COUNT_HW_INSTRUCTIONS },
-	[2] = { 0x80, 0x00, PERF_COUNT_HW_CACHE_REFERENCES },
-	[3] = { 0x81, 0x00, PERF_COUNT_HW_CACHE_MISSES },
+	[2] = { 0x7d, 0x07, PERF_COUNT_HW_CACHE_REFERENCES },
+	[3] = { 0x7e, 0x07, PERF_COUNT_HW_CACHE_MISSES },
 	[4] = { 0xc2, 0x00, PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
 	[5] = { 0xc3, 0x00, PERF_COUNT_HW_BRANCH_MISSES },
 	[6] = { 0xd0, 0x00, PERF_COUNT_HW_STALLED_CYCLES_FRONTEND },
-- 
2.7.3