linux-kernel - [PATCH v1 07/14] perf intel-tpebs: Ensure events are opened, factor out finding

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Message-ID: <20250324223452.208081-8-irogers@google.com>
Date: Mon, 24 Mar 2025 15:34:45 -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>, Weilin Wang <weilin.wang@...el.com>, 
	James Clark <james.clark@...aro.org>, Xu Yang <xu.yang_2@....com>, 
	John Garry <john.g.garry@...cle.com>, Howard Chu <howardchu95@...il.com>, 
	Levi Yun <yeoreum.yun@....com>, Dominique Martinet <asmadeus@...ewreck.org>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 07/14] perf intel-tpebs: Ensure events are opened, factor
 out finding

Factor out finding an tpebs_retire_lat from an evsel. Don't blindly
return when ignoring an open request, which happens after the first
open request, ensure the event was started on a fork of perf record.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/intel-tpebs.c | 61 +++++++++++++++++++++--------------
 1 file changed, 37 insertions(+), 24 deletions(-)

diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
index 3141b7d2e94f..9116cdc6981e 100644
--- a/tools/perf/util/intel-tpebs.c
+++ b/tools/perf/util/intel-tpebs.c
@@ -44,6 +44,8 @@ struct tpebs_retire_lat {
 	int sum;
 	/* Average of retire_latency, val = sum / count */
 	double val;
+	/* Has the event been sent to perf record? */
+	bool started;
 };
 
 static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[], int ack_fd[])
@@ -93,6 +95,9 @@ static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[],
 	tpebs_cmd.out = -1;
 	ret = start_command(&tpebs_cmd);
 	zfree(&tpebs_cmd.argv);
+	list_for_each_entry(t, &tpebs_results, nd)
+		t->started = true;
+
 	return ret;
 }
 
@@ -213,6 +218,19 @@ static struct tpebs_retire_lat *tpebs_retire_lat__new(struct evsel *evsel)
 	return result;
 }
 
+static struct tpebs_retire_lat *tpebs_retire_lat__find(struct evsel *evsel)
+{
+	struct tpebs_retire_lat *t;
+
+	list_for_each_entry(t, &tpebs_results, nd) {
+		if (t->tpebs_name == evsel->name ||
+		    !strcmp(t->tpebs_name, evsel->name) ||
+		    (evsel->metric_id && !strcmp(t->tpebs_name, evsel->metric_id)))
+			return t;
+	}
+	return NULL;
+}
+
 /**
  * evsel__tpebs_prepare - create tpebs data structures ready for opening.
  * @evsel: retire_latency evsel, all evsels on its list will be prepared.
@@ -220,16 +238,11 @@ static struct tpebs_retire_lat *tpebs_retire_lat__new(struct evsel *evsel)
 static int evsel__tpebs_prepare(struct evsel *evsel)
 {
 	struct evsel *pos;
-	struct tpebs_retire_lat *tpebs_event;
-
-	list_for_each_entry(tpebs_event, &tpebs_results, nd) {
-		if (!strcmp(tpebs_event->tpebs_name, evsel->name)) {
-			/*
-			 * evsel, or an identically named one, was already
-			 * prepared.
-			 */
-			return 0;
-		}
+	struct tpebs_retire_lat *tpebs_event = tpebs_retire_lat__find(evsel);
+
+	if (tpebs_event) {
+		/* evsel, or an identically named one, was already prepared. */
+		return 0;
 	}
 	tpebs_event = tpebs_retire_lat__new(evsel);
 	if (!tpebs_event)
@@ -261,12 +274,19 @@ int evsel__tpebs_open(struct evsel *evsel)
 {
 	int ret;
 
-	/*
-	 * We should only run tpebs_start when tpebs_recording is enabled.
-	 * And we should only run it once with all the required events.
-	 */
-	if (tpebs_cmd.pid != 0 || !tpebs_recording)
+	/* We should only run tpebs_start when tpebs_recording is enabled. */
+	if (!tpebs_recording)
 		return 0;
+	/* Only start the events once. */
+	if (tpebs_cmd.pid != 0) {
+		struct tpebs_retire_lat *t = tpebs_retire_lat__find(evsel);
+
+		if (!t || !t->started) {
+			/* Fail, as the event wasn't started. */
+			return -EBUSY;
+		}
+		return 0;
+	}
 
 	ret = evsel__tpebs_prepare(evsel);
 	if (ret)
@@ -351,7 +371,6 @@ int evsel__tpebs_open(struct evsel *evsel)
 int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
 {
 	__u64 val;
-	bool found = false;
 	struct tpebs_retire_lat *t;
 	struct perf_counts_values *count;
 
@@ -366,19 +385,13 @@ int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
 	tpebs_stop();
 	count = perf_counts(evsel->counts, cpu_map_idx, thread);
 
-	list_for_each_entry(t, &tpebs_results, nd) {
-		if (t->tpebs_name == evsel->name ||
-		    (evsel->metric_id && !strcmp(t->tpebs_name, evsel->metric_id))) {
-			found = true;
-			break;
-		}
-	}
+	t = tpebs_retire_lat__find(evsel);
 
 	/* Set ena and run to non-zero */
 	count->ena = count->run = 1;
 	count->lost = 0;
 
-	if (!found) {
+	if (!t) {
 		/*
 		 * Set default value or 0 when retire_latency for this event is
 		 * not found from sampling data (record_tpebs not set or 0
-- 
2.49.0.395.g12beb8f557-goog