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perf stat: Ensure metrics are displayed even with failed events

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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: Ian Rogers <irogers@google.com>
Signed-off-by: Chun-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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Chun-Tse Shao 2026-02-03 15:06:22 -08:00 • committed by Arnaldo Carvalho de Melo
parent 446c595dc0
commit bb5a920b90
3 changed files with 26 additions and 37 deletions
Download patch file Download diff file Expand all files Collapse all files

53
tools/perf/util/stat-display.c
View file

@ -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) {
@ -848,33 +842,32 @@ 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) {
void *from = NULL;
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);
/* Print out all the metricgroup with the same metric event. */
do {
int num = 0;
aggr_printout(config, os, os->evsel, os->id, os->aggr_nr);
/* Print out all the metricgroup with the same metric event. */
do {
int num = 0;
/* Print out the new line for the next new metricgroup. */
if (from) {
if (config->json_output)
new_line_json(config, (void *)os);
else
__new_line_std_csv(config, os);
}
/* Print out the new line for the next new metricgroup. */
if (from) {
if (config->json_output)
new_line_json(config, (void *)os);
else
__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);
} while (from != NULL);
} else {
perf_stat__print_shadow_stats(config, counter, aggr_idx, &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 {
pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/NULL, /*val=*/0);
perf_stat__print_shadow_stats(config, counter, aggr_idx, &out);
}
if (!config->metric_only) {
@ -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))

8
tools/perf/util/stat-shadow.c
View file

@ -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);
}

2
tools/perf/util/stat.h
View file

@ -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,