linux-kernel - [PATCH 2/5] perf lock: Add lock contention tracepoints record support

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Date:   Fri,  3 Jun 2022 16:56:53 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        linux-perf-users@...r.kernel.org, Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Davidlohr Bueso <dave@...olabs.net>
Subject: [PATCH 2/5] perf lock: Add lock contention tracepoints record support

When LOCKDEP and LOCK_STAT events are not available, it falls back to
record the new lock contention tracepoints.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/builtin-lock.c | 74 +++++++++++++++++++++++++++++++++++----
 1 file changed, 67 insertions(+), 7 deletions(-)

diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 57e396323d05..60a45973744d 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -516,17 +516,27 @@ static struct lock_stat *lock_stat_findnew(u64 addr, const char *name)
 }
 
 struct trace_lock_handler {
+	/* it's used on CONFIG_LOCKDEP */
 	int (*acquire_event)(struct evsel *evsel,
 			     struct perf_sample *sample);
 
+	/* it's used on CONFIG_LOCK_STAT */
 	int (*acquired_event)(struct evsel *evsel,
 			      struct perf_sample *sample);
 
+	/* it's used on CONFIG_LOCK_STAT */
 	int (*contended_event)(struct evsel *evsel,
 			       struct perf_sample *sample);
 
+	/* it's used on CONFIG_LOCKDEP */
 	int (*release_event)(struct evsel *evsel,
 			     struct perf_sample *sample);
+
+	int (*contention_begin_event)(struct evsel *evsel,
+				      struct perf_sample *sample);
+
+	int (*contention_end_event)(struct evsel *evsel,
+				    struct perf_sample *sample);
 };
 
 static struct lock_seq_stat *get_seq(struct thread_stat *ts, u64 addr)
@@ -854,6 +864,20 @@ static int evsel__process_lock_release(struct evsel *evsel, struct perf_sample *
 	return 0;
 }
 
+static int evsel__process_contention_begin(struct evsel *evsel, struct perf_sample *sample)
+{
+	if (trace_handler->contention_begin_event)
+		return trace_handler->contention_begin_event(evsel, sample);
+	return 0;
+}
+
+static int evsel__process_contention_end(struct evsel *evsel, struct perf_sample *sample)
+{
+	if (trace_handler->contention_end_event)
+		return trace_handler->contention_end_event(evsel, sample);
+	return 0;
+}
+
 static void print_bad_events(int bad, int total)
 {
 	/* Output for debug, this have to be removed */
@@ -1055,6 +1079,11 @@ static const struct evsel_str_handler lock_tracepoints[] = {
 	{ "lock:lock_release",	 evsel__process_lock_release,   }, /* CONFIG_LOCKDEP */
 };
 
+static const struct evsel_str_handler contention_tracepoints[] = {
+	{ "lock:contention_begin", evsel__process_contention_begin, },
+	{ "lock:contention_end",   evsel__process_contention_end,   },
+};
+
 static bool force;
 
 static int __cmd_report(bool display_info)
@@ -1118,20 +1147,41 @@ static int __cmd_record(int argc, const char **argv)
 		"record", "-R", "-m", "1024", "-c", "1", "--synth", "task",
 	};
 	unsigned int rec_argc, i, j, ret;
+	unsigned int nr_tracepoints;
 	const char **rec_argv;
+	bool has_lock_stat = true;
 
 	for (i = 0; i < ARRAY_SIZE(lock_tracepoints); i++) {
 		if (!is_valid_tracepoint(lock_tracepoints[i].name)) {
-				pr_err("tracepoint %s is not enabled. "
-				       "Are CONFIG_LOCKDEP and CONFIG_LOCK_STAT enabled?\n",
-				       lock_tracepoints[i].name);
-				return 1;
+			pr_debug("tracepoint %s is not enabled. "
+				 "Are CONFIG_LOCKDEP and CONFIG_LOCK_STAT enabled?\n",
+				 lock_tracepoints[i].name);
+			has_lock_stat = false;
+			break;
+		}
+	}
+
+	if (has_lock_stat)
+		goto setup_args;
+
+	for (i = 0; i < ARRAY_SIZE(contention_tracepoints); i++) {
+		if (!is_valid_tracepoint(contention_tracepoints[i].name)) {
+			pr_err("tracepoint %s is not enabled.\n",
+			       contention_tracepoints[i].name);
+			return 1;
 		}
 	}
 
+setup_args:
 	rec_argc = ARRAY_SIZE(record_args) + argc - 1;
+
+	if (has_lock_stat)
+		nr_tracepoints = ARRAY_SIZE(lock_tracepoints);
+	else
+		nr_tracepoints = ARRAY_SIZE(contention_tracepoints);
+
 	/* factor of 2 is for -e in front of each tracepoint */
-	rec_argc += 2 * ARRAY_SIZE(lock_tracepoints);
+	rec_argc += 2 * nr_tracepoints;
 
 	rec_argv = calloc(rec_argc + 1, sizeof(char *));
 	if (!rec_argv)
@@ -1140,9 +1190,19 @@ static int __cmd_record(int argc, const char **argv)
 	for (i = 0; i < ARRAY_SIZE(record_args); i++)
 		rec_argv[i] = strdup(record_args[i]);
 
-	for (j = 0; j < ARRAY_SIZE(lock_tracepoints); j++) {
+	for (j = 0; j < nr_tracepoints; j++) {
+		const char *ev_name;
+
+		if (has_lock_stat)
+			ev_name = strdup(lock_tracepoints[j].name);
+		else
+			ev_name = strdup(contention_tracepoints[j].name);
+
+		if (!ev_name)
+			return -ENOMEM;
+
 		rec_argv[i++] = "-e";
-		rec_argv[i++] = strdup(lock_tracepoints[j].name);
+		rec_argv[i++] = ev_name;
 	}
 
 	for (j = 1; j < (unsigned int)argc; j++, i++)
-- 
2.36.1.255.ge46751e96f-goog