perf pmus: Add function to return count of core PMUs

Add perf_pmus__num_core_pmus that will count core PMUs holding the
result in a static. Reuse for perf_pmus__num_mem_pmus.

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ali Saidi <alisaidi@amazon.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kang Minchul <tegongkang@gmail.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230527072210.2900565-33-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pmus.c

@@ -229,14 +229,8 @@ const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str)
 
 int perf_pmus__num_mem_pmus(void)
 {
-	struct perf_pmu *pmu = NULL;
-	int count = 0;
-
 	/* All core PMUs are for mem events. */
-	while ((pmu = perf_pmus__scan_core(pmu)) != NULL)
-		count++;
-
-	return count;
+	return perf_pmus__num_core_pmus();
 }
 
 /** Struct for ordering events as output in perf list. */
@@ -488,6 +482,19 @@ bool perf_pmus__has_hybrid(void)
 	return has_hybrid;
 }
 
+int perf_pmus__num_core_pmus(void)
+{
+	static int count;
+
+	if (!count) {
+		struct perf_pmu *pmu = NULL;
+
+		while ((pmu = perf_pmus__scan_core(pmu)) != NULL)
+			count++;
+	}
+	return count;
+}
+
 struct perf_pmu *evsel__find_pmu(const struct evsel *evsel)
 {
 	struct perf_pmu *pmu = evsel->pmu;

tools/perf/util/pmus.h

@@ -19,5 +19,6 @@ int perf_pmus__num_mem_pmus(void);
 void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *print_state);
 bool perf_pmus__have_event(const char *pname, const char *name);
 bool perf_pmus__has_hybrid(void);
+int perf_pmus__num_core_pmus(void);
 
 #endif /* __PMUS_H */