[PATCH v3 5/8] perf sched stats: Add support for live mode

Swapnil Sapkal
2025-03-11T12:05:03Z

The live mode works similar to simple `perf stat` command, by profiling
the target and printing results on the terminal as soon as the target
finishes.

Example usage:

# perf sched stats -- sleep 10

Co-developed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
---
tools/perf/builtin-sched.c | 87 +++++++++++++++++++++++++++++++++++++-
1 file changed, 86 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index e2e7dbc4f0aa..9813e25b54b8 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -4364,6 +4364,91 @@ static int perf_sched__schedstat_report(struct perf_sched *sched)
return err;
}

+static int process_synthesized_event_live(const struct perf_tool *tool __maybe_unused,
+ union perf_event *event,
+ struct perf_sample *sample __maybe_unused,
+ struct machine *machine __maybe_unused)
+{
+ return perf_sched__process_schedstat(NULL, event);
+}
+
+static int perf_sched__schedstat_live(struct perf_sched *sched,
+ int argc, const char **argv)
+{
+ struct evlist *evlist;
+ struct target *target;
+ int reset = 0;
+ int err = 0;
+
+ signal(SIGINT, sighandler);
+ signal(SIGCHLD, sighandler);
+ signal(SIGTERM, sighandler);
+
+ evlist = evlist__new();
+ if (!evlist)
+ return -ENOMEM;
+
+ /*
+ * `perf sched schedstat` does not support workload profiling (-p pid)
+ * since /proc/schedstat file contains cpu specific data only. Hence, a
+ * profile target is either set of cpus or systemwide, never a process.
+ * Note that, although `-- <workload>` is supported, profile data are
+ * still cpu/systemwide.
+ */
+ target = zalloc(sizeof(struct target));
+ if (cpu_list)
+ target->cpu_list = cpu_list;
+ else
+ target->system_wide = true;
+
+ if (argc) {
+ err = evlist__prepare_workload(evlist, target, argv, false, NULL);
+ if (err)
+ goto out_target;
+ }
+
+ if (cpu_list) {
+ user_requested_cpus = perf_cpu_map__new(cpu_list);
+ if (!user_requested_cpus)
+ goto out_target;
+ }
+
+ err = perf_event__synthesize_schedstat(&(sched->tool),
+ process_synthesized_event_live,
+ user_requested_cpus);
+ if (err < 0)
+ goto out_target;
+
+ err = enable_sched_schedstats(&reset);
+ if (err < 0)
+ goto out_target;
+
+ if (argc)
+ evlist__start_workload(evlist);
+
+ /* wait for signal */
+ pause();
+
+ if (reset) {
+ err = disable_sched_schedstat();
+ if (err < 0)
+ goto out_target;
+ }
+
+ err = perf_event__synthesize_schedstat(&(sched->tool),
+ process_synthesized_event_live,
+ user_requested_cpus);
+ if (err)
+ goto out_target;
+
+ setup_pager();
+ show_schedstat_data(cpu_head);
+ free_schedstat(cpu_head);
+out_target:
+ free(target);
+ return err;
+}
+
static bool schedstat_events_exposed(void)
{
/*
@@ -4686,7 +4771,7 @@ int cmd_sched(int argc, const char **argv)
stats_usage, 0);
return perf_sched__schedstat_report(&sched);
}
- usage_with_options(stats_usage, stats_options);
+ return perf_sched__schedstat_live(&sched, argc, argv);
} else {
usage_with_options(sched_usage, sched_options);
}
--
2.43.0