[PATCH v4] perf sched: Fix sched latency analysis incorrect

From: Chunxin Zang
Date: Tue Mar 28 2023 - 02:01:08 EST


'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@xxxxxxxxxxx>
Signed-off-by: Jerry Zhou <zhouchunhua@xxxxxxxxxxx>
---

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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