perf sched: Prefer sched_waking event when it exists

Commit fbd705a0c6 ("sched: Introduce the 'trace_sched_waking'
tracepoint") added sched_waking tracepoint which should be preferred
over sched_wakeup when analyzing scheduling delays.

Update 'perf sched record' to collect sched_waking events if it exists
and fallback to sched_wakeup if it does not. Similarly, update timehist
command to skip sched_wakeup events if the session includes sched_waking
(ie., sched_waking is preferred over sched_wakeup).

Signed-off-by: David Ahern <dsahern@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20200807164844.44870-1-dsahern@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-sched.c

@@ -2398,6 +2398,15 @@ static void timehist_print_wakeup_event(struct perf_sched *sched,
 	printf("\n");
 }
 
+static int timehist_sched_wakeup_ignore(struct perf_tool *tool __maybe_unused,
+					union perf_event *event __maybe_unused,
+					struct evsel *evsel __maybe_unused,
+					struct perf_sample *sample __maybe_unused,
+					struct machine *machine __maybe_unused)
+{
+	return 0;
+}
+
 static int timehist_sched_wakeup_event(struct perf_tool *tool,
 				       union perf_event *event __maybe_unused,
 				       struct evsel *evsel,
@@ -2958,9 +2967,10 @@ static int timehist_check_attr(struct perf_sched *sched,
 
 static int perf_sched__timehist(struct perf_sched *sched)
 {
-	const struct evsel_str_handler handlers[] = {
+	struct evsel_str_handler handlers[] = {
 		{ "sched:sched_switch",       timehist_sched_switch_event, },
 		{ "sched:sched_wakeup",	      timehist_sched_wakeup_event, },
+		{ "sched:sched_waking",       timehist_sched_wakeup_event, },
 		{ "sched:sched_wakeup_new",   timehist_sched_wakeup_event, },
 	};
 	const struct evsel_str_handler migrate_handlers[] = {
@@ -3018,6 +3028,11 @@ static int perf_sched__timehist(struct perf_sched *sched)
 
 	setup_pager();
 
+	/* prefer sched_waking if it is captured */
+	if (perf_evlist__find_tracepoint_by_name(session->evlist,
+						  "sched:sched_waking"))
+		handlers[1].handler = timehist_sched_wakeup_ignore;
+
 	/* setup per-evsel handlers */
 	if (perf_session__set_tracepoints_handlers(session, handlers))
 		goto out;
@@ -3330,12 +3345,16 @@ static int __cmd_record(int argc, const char **argv)
 		"-e", "sched:sched_stat_iowait",
 		"-e", "sched:sched_stat_runtime",
 		"-e", "sched:sched_process_fork",
-		"-e", "sched:sched_wakeup",
 		"-e", "sched:sched_wakeup_new",
 		"-e", "sched:sched_migrate_task",
 	};
+	struct tep_event *waking_event;
 
-	rec_argc = ARRAY_SIZE(record_args) + argc - 1;
+	/*
+	 * +2 for either "-e", "sched:sched_wakeup" or
+	 * "-e", "sched:sched_waking"
+	 */
+	rec_argc = ARRAY_SIZE(record_args) + 2 + argc - 1;
 	rec_argv = calloc(rec_argc + 1, sizeof(char *));
 
 	if (rec_argv == NULL)
@@ -3344,6 +3363,13 @@ 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]);
 
+	rec_argv[i++] = "-e";
+	waking_event = trace_event__tp_format("sched", "sched_waking");
+	if (!IS_ERR(waking_event))
+		rec_argv[i++] = strdup("sched:sched_waking");
+	else
+		rec_argv[i++] = strdup("sched:sched_wakeup");
+
 	for (j = 1; j < (unsigned int)argc; j++, i++)
 		rec_argv[i] = argv[j];