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

Sapkal, Swapnil
2025-03-24T09:16:13Z

Hi Namhyung,

Sorry for the delay in response.

On 3/15/2025 10:16 AM, Namhyung Kim wrote:
> On Tue, Mar 11, 2025 at 12:02:27PM +0000, Swapnil Sapkal wrote:
>> 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));
>
> As I said, you can put it on stack.
>

Sure.

>
>> + 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;
>> + }
>
> How about this instead?
>
> evlist__create_maps(evlist, target);
>

Sure, will use evlist__create_maps(evlist, 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);
>
> evlist__delete(evlist);
>
> and unless you use evlist__create_maps().
>

Ack.

> perf_cpu_map__put(user_requested_cpus);
>
> Thanks,
> Namhyung
>
>
>> + 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
>>
--
Thanks and Regards,
Swapnil