linux-kernel - [PATCH v8 4/4] perf perf_api_probe: Avoid scanning all PMUs, try software PMU first

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Message-ID: <20250416045117.876775-5-irogers@google.com>
Date: Tue, 15 Apr 2025 21:51:17 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, James Clark <james.clark@...aro.org>, 
	Ze Gao <zegao2021@...il.com>, Weilin Wang <weilin.wang@...el.com>, 
	Dominique Martinet <asmadeus@...ewreck.org>, 
	Jean-Philippe Romain <jean-philippe.romain@...s.st.com>, Junhao He <hejunhao3@...wei.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Aditya Bodkhe <Aditya.Bodkhe1@....com>, Leo Yan <leo.yan@....com>, 
	Thomas Falcon <thomas.falcon@...el.com>, Atish Patra <atishp@...osinc.com>
Subject: [PATCH v8 4/4] perf perf_api_probe: Avoid scanning all PMUs, try
 software PMU first

Add PMU names when geting events to probe. The first is only ever used
but by not specifying a PMU name perf_api_probe will load all the
PMUs.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/perf_api_probe.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/perf_api_probe.c b/tools/perf/util/perf_api_probe.c
index 1de3b69cdf4a..a910cde4d78b 100644
--- a/tools/perf/util/perf_api_probe.c
+++ b/tools/perf/util/perf_api_probe.c
@@ -59,10 +59,10 @@ static int perf_do_probe_api(setup_probe_fn_t fn, struct perf_cpu cpu, const cha
 
 static bool perf_probe_api(setup_probe_fn_t fn)
 {
-	const char *try[] = {"cycles:u", "instructions:u", "cpu-clock:u", NULL};
+	struct perf_pmu *pmu;
 	struct perf_cpu_map *cpus;
 	struct perf_cpu cpu;
-	int ret, i = 0;
+	int ret = 0;
 
 	cpus = perf_cpu_map__new_online_cpus();
 	if (!cpus)
@@ -70,12 +70,23 @@ static bool perf_probe_api(setup_probe_fn_t fn)
 	cpu = perf_cpu_map__cpu(cpus, 0);
 	perf_cpu_map__put(cpus);
 
-	do {
-		ret = perf_do_probe_api(fn, cpu, try[i++]);
-		if (!ret)
-			return true;
-	} while (ret == -EAGAIN && try[i]);
-
+	ret = perf_do_probe_api(fn, cpu, "software/cpu-clock/u");
+	if (!ret)
+		return true;
+
+	pmu = perf_pmus__scan_core(/*pmu=*/NULL);
+	if (pmu) {
+		const char *try[] = {"cycles", "instructions", NULL};
+		char buf[256];
+		int i = 0;
+
+		 while (ret == -EAGAIN && try[i]) {
+			snprintf(buf, sizeof(buf), "%s/%s/u", pmu->name, try[i++]);
+			ret = perf_do_probe_api(fn, cpu, buf);
+			if (!ret)
+				return true;
+		}
+	}
 	return false;
 }
 
-- 
2.49.0.777.g153de2bbd5-goog