linux-kernel - [PATCH V2 4/4] perf parse-events: Move slots event for the hybrid platform too

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Date:   Mon, 16 May 2022 08:24:36 -0700
From:   kan.liang@...ux.intel.com
To:     acme@...nel.org, mingo@...hat.com, irogers@...gle.com,
        jolsa@...nel.org, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Cc:     peterz@...radead.org, zhengjun.xing@...ux.intel.com,
        adrian.hunter@...el.com, ak@...ux.intel.com, eranian@...gle.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V2 4/4] perf parse-events: Move slots event for the hybrid platform too

From: Kan Liang <kan.liang@...ux.intel.com>

The commit 94dbfd6781a0 ("perf parse-events: Architecture specific
leader override") introduced a feature to reorder the slots event to
fulfill the restriction of the perf metrics topdown group. But the
feature doesn't work on the hybrid machine.

$perf stat -e "{cpu_core/instructions/,cpu_core/slots/,cpu_core/topdown-retiring/}" -a sleep 1

 Performance counter stats for 'system wide':

     <not counted>      cpu_core/instructions/
     <not counted>      cpu_core/slots/
   <not supported>      cpu_core/topdown-retiring/

       1.002871801 seconds time elapsed

A hybrid platform has a different PMU name for the core PMUs, while
current perf hard code the PMU name "cpu".

Introduce a new function to check whether the system supports the perf
metrics feature. The result is cached for the future usage.

For X86, the core PMU name always has "cpu" prefix.

With the patch,

$perf stat -e "{cpu_core/instructions/,cpu_core/slots/,cpu_core/topdown-retiring/}" -a sleep 1

 Performance counter stats for 'system wide':

        76,337,010      cpu_core/slots/
        10,416,809      cpu_core/instructions/
        11,692,372      cpu_core/topdown-retiring/

       1.002805453 seconds time elapsed

Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 tools/perf/arch/x86/util/evlist.c  |  5 +++--
 tools/perf/arch/x86/util/topdown.c | 24 ++++++++++++++++++++++++
 tools/perf/arch/x86/util/topdown.h |  7 +++++++
 3 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 tools/perf/arch/x86/util/topdown.h

diff --git a/tools/perf/arch/x86/util/evlist.c b/tools/perf/arch/x86/util/evlist.c
index 75564a7df15b..68f681ad54c1 100644
--- a/tools/perf/arch/x86/util/evlist.c
+++ b/tools/perf/arch/x86/util/evlist.c
@@ -3,6 +3,7 @@
 #include "util/pmu.h"
 #include "util/evlist.h"
 #include "util/parse-events.h"
+#include "topdown.h"
 
 #define TOPDOWN_L1_EVENTS	"{slots,topdown-retiring,topdown-bad-spec,topdown-fe-bound,topdown-be-bound}"
 #define TOPDOWN_L2_EVENTS	"{slots,topdown-retiring,topdown-bad-spec,topdown-fe-bound,topdown-be-bound,topdown-heavy-ops,topdown-br-mispredict,topdown-fetch-lat,topdown-mem-bound}"
@@ -25,12 +26,12 @@ struct evsel *arch_evlist__leader(struct list_head *list)
 
 	first = list_first_entry(list, struct evsel, core.node);
 
-	if (!pmu_have_event("cpu", "slots"))
+	if (!topdown_sys_has_perf_metrics())
 		return first;
 
 	/* If there is a slots event and a topdown event then the slots event comes first. */
 	__evlist__for_each_entry(list, evsel) {
-		if (evsel->pmu_name && !strcmp(evsel->pmu_name, "cpu") && evsel->name) {
+		if (evsel->pmu_name && !strncmp(evsel->pmu_name, "cpu", 3) && evsel->name) {
 			if (strcasestr(evsel->name, "slots")) {
 				slots = evsel;
 				if (slots == first)
diff --git a/tools/perf/arch/x86/util/topdown.c b/tools/perf/arch/x86/util/topdown.c
index 2f3d96aa92a5..5e86859279e3 100644
--- a/tools/perf/arch/x86/util/topdown.c
+++ b/tools/perf/arch/x86/util/topdown.c
@@ -3,6 +3,30 @@
 #include "api/fs/fs.h"
 #include "util/pmu.h"
 #include "util/topdown.h"
+#include "topdown.h"
+
+bool topdown_sys_has_perf_metrics(void)
+{
+	static bool has_perf_metrics;
+	static bool cached;
+	struct perf_pmu *pmu;
+
+	if (cached)
+		return has_perf_metrics;
+
+	/*
+	 * The perf metrics feature is a core PMU feature.
+	 * The PERF_TYPE_RAW type is the type of a core PMU.
+	 * The slots event is only available when the core PMU
+	 * supports the perf metrics feature.
+	 */
+	pmu = perf_pmu__find_by_type(PERF_TYPE_RAW);
+	if (pmu && pmu_have_event(pmu->name, "slots"))
+		has_perf_metrics = true;
+
+	cached = true;
+	return has_perf_metrics;
+}
 
 /*
  * Check whether we can use a group for top down.
diff --git a/tools/perf/arch/x86/util/topdown.h b/tools/perf/arch/x86/util/topdown.h
new file mode 100644
index 000000000000..46bf9273e572
--- /dev/null
+++ b/tools/perf/arch/x86/util/topdown.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TOPDOWN_H
+#define _TOPDOWN_H 1
+
+bool topdown_sys_has_perf_metrics(void);
+
+#endif
-- 
2.35.1