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: 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>

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 2ce0602..dc2b668 100644 (file)
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -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;
-
-                       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_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);
-               }
+       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;
+
+                       /* 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 {
-               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))

diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index 9c83f7d..5d8d09e 100644 (file)
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -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);
 }

diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index f986911..4bced23 100644 (file)
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -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,