linux-kernel - [PATCH v4] perf sched: Fix sched latency analysis incorrect

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Date:   Tue, 28 Mar 2023 14:00:57 +0800
From:   "Chunxin Zang" <zangchunxin@...iang.com>
To:     <namhyung@...nel.org>, <peterz@...radead.org>, <mingo@...hat.com>,
        <acme@...nel.org>
Cc:     <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...nel.org>, <irogers@...gle.com>,
        <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Chunxin Zang" <zangchunxin@...iang.com>,
        "Jerry Zhou" <zhouchunhua@...iang.com>
Subject: [PATCH v4] perf sched: Fix sched latency analysis incorrect

'perf sched latency' is incorrect to get process schedule latency
when it used 'sched:sched_wakeup' to analysis perf.data.

Because 'perf record' prefer use 'sched:sched_waking' to
'sched:sched_wakeup' since commit d566a9c2d482 ("perf sched: Prefer
sched_waking event when it exists"). It's very reasonable to
evaluate process schedule latency.

Similarly, update sched latency/map/replay to use sched_waking events.

Signed-off-by: Chunxin Zang <zangchunxin@...iang.com>
Signed-off-by: Jerry Zhou <zhouchunhua@...iang.com>
---

	changelogs in v4:
	1) disable to process wakeup event if wakingup event is found.

	changelogs in v3:
	1) fix non-ASCII characters in commit log.

	changelogs in v2:
	1) fix email address disappearing in 'signed off by'

 tools/perf/builtin-sched.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 86e18575c9be..ec443df8e05c 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1516,6 +1516,14 @@ static int process_sched_wakeup_event(struct perf_tool *tool,
 	return 0;
 }
 
+static int process_sched_wakeup_ignore(struct perf_tool *tool __maybe_unused,
+				      struct evsel *evsel __maybe_unused,
+				      struct perf_sample *sample __maybe_unused,
+				      struct machine *machine __maybe_unused)
+{
+	return 0;
+}
+
 union map_priv {
 	void	*ptr;
 	bool	 color;
@@ -1816,10 +1824,11 @@ static int perf_sched__process_comm(struct perf_tool *tool __maybe_unused,
 
 static int perf_sched__read_events(struct perf_sched *sched)
 {
-	const struct evsel_str_handler handlers[] = {
+	struct evsel_str_handler handlers[] = {
 		{ "sched:sched_switch",	      process_sched_switch_event, },
 		{ "sched:sched_stat_runtime", process_sched_runtime_event, },
 		{ "sched:sched_wakeup",	      process_sched_wakeup_event, },
+		{ "sched:sched_waking",	      process_sched_wakeup_event, },
 		{ "sched:sched_wakeup_new",   process_sched_wakeup_event, },
 		{ "sched:sched_migrate_task", process_sched_migrate_task_event, },
 	};
@@ -1839,6 +1848,10 @@ static int perf_sched__read_events(struct perf_sched *sched)
 
 	symbol__init(&session->header.env);
 
+	/* prefer sched_waking if it is captured */
+	if (evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
+		handlers[2].handler = process_sched_wakeup_ignore;
+
 	if (perf_session__set_tracepoints_handlers(session, handlers))
 		goto out_delete;
 
-- 
2.25.1

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