linux-kernel - [PATCH 1/2] perf/x86/amd/core: Update stalled-cycles-* events for Zen 2 and later

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Date: Mon, 25 Mar 2024 13:17:53 +0530
From: Sandipan Das <sandipan.das@....com>
To: <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <x86@...nel.org>, <peterz@...radead.org>, <mingo@...nel.org>,
	<acme@...nel.org>, <namhyung@...nel.org>, <mark.rutland@....com>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
	<adrian.hunter@...el.com>, <tglx@...utronix.de>, <bp@...en8.de>,
	<eranian@...gle.com>, <irogers@...gle.com>, <ravi.bangoria@....com>,
	<ananth.narayan@....com>, <sandipan.das@....com>
Subject: [PATCH 1/2] perf/x86/amd/core: Update stalled-cycles-* events for Zen 2 and later

AMD processors based on Zen 2 and later microarchitectures do not
support PMCx087 (instruction pipe stalls) which is used as the backing
event for "stalled-cycles-frontend" and "stalled-cycles-backend". Use
PMCx0A9 (cycles where micro-op queue is empty) instead to count frontend
stalls and remove the entry for backend stalls since there is no direct
replacement.

Signed-off-by: Sandipan Das <sandipan.das@....com>
---
 arch/x86/events/amd/core.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index aec16e581f5b..afe4a809f2ed 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -250,7 +250,7 @@ static const u64 amd_perfmon_event_map[PERF_COUNT_HW_MAX] =
 /*
  * AMD Performance Monitor Family 17h and later:
  */
-static const u64 amd_f17h_perfmon_event_map[PERF_COUNT_HW_MAX] =
+static const u64 amd_zen1_perfmon_event_map[PERF_COUNT_HW_MAX] =
 {
 	[PERF_COUNT_HW_CPU_CYCLES]		= 0x0076,
 	[PERF_COUNT_HW_INSTRUCTIONS]		= 0x00c0,
@@ -262,10 +262,24 @@ static const u64 amd_f17h_perfmon_event_map[PERF_COUNT_HW_MAX] =
 	[PERF_COUNT_HW_STALLED_CYCLES_BACKEND]	= 0x0187,
 };
 
+static const u64 amd_zen2_perfmon_event_map[PERF_COUNT_HW_MAX] =
+{
+	[PERF_COUNT_HW_CPU_CYCLES]		= 0x0076,
+	[PERF_COUNT_HW_INSTRUCTIONS]		= 0x00c0,
+	[PERF_COUNT_HW_CACHE_REFERENCES]	= 0xff60,
+	[PERF_COUNT_HW_CACHE_MISSES]		= 0x0964,
+	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= 0x00c2,
+	[PERF_COUNT_HW_BRANCH_MISSES]		= 0x00c3,
+	[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= 0x00a9,
+};
+
 static u64 amd_pmu_event_map(int hw_event)
 {
-	if (boot_cpu_data.x86 >= 0x17)
-		return amd_f17h_perfmon_event_map[hw_event];
+	if (cpu_feature_enabled(X86_FEATURE_ZEN2) || boot_cpu_data.x86 >= 0x19)
+		return amd_zen2_perfmon_event_map[hw_event];
+
+	if (cpu_feature_enabled(X86_FEATURE_ZEN1))
+		return amd_zen1_perfmon_event_map[hw_event];
 
 	return amd_perfmon_event_map[hw_event];
 }
-- 
2.34.1