[PATCH 1/2] perf sched: Prefer sched_waking event when it exists

David Ahern
2020-08-07T16:48:56Z

Commit fbd705a0c618 ("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>
---
tools/perf/builtin-sched.c | 32 +++++++++++++++++++++++++++++---
1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 459e4229945e..0c7d599fa555 100644
--- a/tools/perf/builtin-sched.c
+++ b/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];

--
2.17.1