Commit bb5a920b authored by Chun-Tse Shao's avatar Chun-Tse Shao Committed by Arnaldo Carvalho de Melo
Browse files

perf stat: Ensure metrics are displayed even with failed events 



Currently, `perf stat` skips or hides metrics when the underlying
hardware events cannot be counted (e.g., due to insufficient permissions
or unsupported events).

In `--metric-only` mode, this often results in missing columns or blank
spaces, making the output difficult to parse.

Modify the logic to ensure metrics are consistently displayed by
propagating NAN (Not a Number) through the expression evaluator.
Specifically:

1. Update `prepare_metric()` in stat-shadow.c to treat uncounted events
   (where `run == 0`) as NAN. This leverages the existing math in expr.y
   to propagate NAN through metric expressions.

2. Remove the early return in the display logic's `printout()` function
   that was previously skipping metrics in `--metric-only` mode for
   failed events.
l
3. Simplify `perf_stat__skip_metric_event()` to no longer depend on
   event runtime.

Tested:

1. `perf all metrics test` did not crash while paranoid is 2.

2. Multiple combinations with `CPUs_utilized` while paranoid is 2.

  $ ./perf stat -M CPUs_utilized -a -- sleep 1

   Performance counter stats for 'system wide':

     <not supported> msec cpu-clock:u                      #      nan CPUs  CPUs_utilized
       1,006,356,120      duration_time

         1.004375550 seconds time elapsed

  $ ./perf stat -M CPUs_utilized -a -j -- sleep 1
  {"counter-value" : "<not supported>", "unit" : "msec", "event" : "cpu-clock:u", "event-runtime" : 0, "pcnt-running" : 100.00, "metric-value" : "nan", "metric-unit" : "CPUs  CPUs_utilized"}
  {"counter-value" : "1006642462.000000", "unit" : "", "event" : "duration_time", "event-runtime" : 1, "pcnt-running" : 100.00}

  $ ./perf stat -M CPUs_utilized -a --metric-only -- sleep 1

   Performance counter stats for 'system wide':

    CPUs  CPUs_utilized
                      nan

         1.004424652 seconds time elapsed

  $ ./perf stat -M CPUs_utilized -a --metric-only -j -- sleep 1
  {"CPUs  CPUs_utilized" : "none"}

Reviewed-by: default avatarIan Rogers <irogers@google.com>
Signed-off-by: default avatarChun-Tse Shao <ctshao@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 446c595d

tools/perf/util/stat-display.c

+26 −33
Original line number Diff line number Diff line
@@ -820,12 +820,6 @@ static void printout(struct perf_stat_config *config, struct outstate *os, 
	}



	if (run == 0 || ena == 0 || counter->counts->scaled == -1) {

		if (config->metric_only) {

			pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL,

			   /*unit=*/NULL, /*val=*/0);

			return;

		}



		ok = false;



		if (counter->supported) {
@@ -848,8 +842,8 @@ static void printout(struct perf_stat_config *config, struct outstate *os, 
		print_running(config, os, run, ena, /*before_metric=*/true);

	}



	if (ok) {

		if (!config->metric_only && counter->default_metricgroup && !counter->default_show_events) {

	if (!config->metric_only && counter->default_metricgroup &&

	    !counter->default_show_events) {

		void *from = NULL;



		aggr_printout(config, os, os->evsel, os->id, os->aggr_nr);
@@ -865,17 +859,16 @@ static void printout(struct perf_stat_config *config, struct outstate *os, 
					__new_line_std_csv(config, os);

			}



				print_noise(config, os, counter, noise, /*before_metric=*/true);

				print_running(config, os, run, ena, /*before_metric=*/true);

				from = perf_stat__print_shadow_stats_metricgroup(config, counter, aggr_idx,

										 &num, from, &out);

			print_noise(config, os, counter, noise,

				    /*before_metric=*/true);

			print_running(config, os, run, ena,

				      /*before_metric=*/true);

			from = perf_stat__print_shadow_stats_metricgroup(

				config, counter, aggr_idx, &num, from, &out);

		} while (from != NULL);

	} else {

		perf_stat__print_shadow_stats(config, counter, aggr_idx, &out);

	}

	} else {

		pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/NULL, /*val=*/0);

	}



	if (!config->metric_only) {

		print_noise(config, os, counter, noise, /*before_metric=*/false);
@@ -987,7 +980,7 @@ static void print_counter_aggrdata(struct perf_stat_config *config, 
	ena = aggr->counts.ena;

	run = aggr->counts.run;



	if (perf_stat__skip_metric_event(counter, ena, run))

	if (perf_stat__skip_metric_event(counter))

		return;



	if (val == 0 && should_skip_zero_counter(config, counter, &id))

tools/perf/util/stat-shadow.c

+2 −6
Original line number Diff line number Diff line
@@ -83,7 +83,7 @@ static int prepare_metric(struct perf_stat_config *config, 
		}

		/* Time events are always on CPU0, the first aggregation index. */

		aggr = &ps->aggr[is_tool_time ? tool_aggr_idx : aggr_idx];

		if (!aggr || !metric_events[i]->supported) {

		if (!aggr || !metric_events[i]->supported || aggr->counts.run == 0) {

			/*

			 * Not supported events will have a count of 0, which

			 * can be confusing in a metric. Explicitly set the
@@ -335,14 +335,10 @@ void perf_stat__print_shadow_stats(struct perf_stat_config *config, 
 * perf_stat__skip_metric_event - Skip the evsel in the Default metricgroup,

 *				  if it's not running or not the metric event.

 */

bool perf_stat__skip_metric_event(struct evsel *evsel,

				  u64 ena, u64 run)

bool perf_stat__skip_metric_event(struct evsel *evsel)

{

	if (!evsel->default_metricgroup)

		return false;



	if (!ena || !run)

		return true;



	return !metricgroup__lookup(&evsel->evlist->metric_events, evsel, false);

}

tools/perf/util/stat.h

+1 −1
Original line number Diff line number Diff line
@@ -163,7 +163,7 @@ void perf_stat__print_shadow_stats(struct perf_stat_config *config, 
				   struct evsel *evsel,

				   int aggr_idx,

				   struct perf_stat_output_ctx *out);

bool perf_stat__skip_metric_event(struct evsel *evsel, u64 ena, u64 run);

bool perf_stat__skip_metric_event(struct evsel *evsel);

void *perf_stat__print_shadow_stats_metricgroup(struct perf_stat_config *config,

						struct evsel *evsel,

						int aggr_idx,