From bb5a920b9099127915706fdd23eb540c9a69c338 Mon Sep 17 00:00:00 2001 From: Chun-Tse Shao Date: Tue, 3 Feb 2026 15:06:22 -0800 Subject: [PATCH] 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': 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" : "", "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 Signed-off-by: Chun-Tse Shao Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Yang Li Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/stat-display.c | 53 +++++++++++++++------------------- tools/perf/util/stat-shadow.c | 8 ++--- tools/perf/util/stat.h | 2 +- 3 files changed, 26 insertions(+), 37 deletions(-) diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c index 2ce0602974a1..dc2b66855f6c 100644 --- 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; + 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)) diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c index 9c83f7d96caa..5d8d09e0e6ae 100644 --- 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 f986911c9296..4bced233d2fc 100644 --- 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,