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Message-ID: <aRvaK32xmC8XUA-k@google.com>
Date: Mon, 17 Nov 2025 18:30:03 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
"Dr. David Alan Gilbert" <linux@...blig.org>,
Yang Li <yang.lee@...ux.alibaba.com>,
James Clark <james.clark@...aro.org>,
Thomas Falcon <thomas.falcon@...el.com>,
Thomas Richter <tmricht@...ux.ibm.com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Andi Kleen <ak@...ux.intel.com>,
Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: Re: [PATCH v4 04/10] perf stat-shadow: Read tool events directly
On Thu, Nov 13, 2025 at 10:05:10AM -0800, Ian Rogers wrote:
> When reading time values for metrics don't use the globals updated in
> builtin-stat, just read the events as regular events. The only
> exception is for time events where nanoseconds need converting to
> seconds as metrics assume time metrics are in seconds.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> tools/perf/util/stat-shadow.c | 149 +++++++++++++++-------------------
> 1 file changed, 66 insertions(+), 83 deletions(-)
>
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index b3b482e1808f..6c1ad78604e1 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/tools/perf/util/stat-shadow.c
> @@ -26,7 +26,32 @@ void perf_stat__reset_shadow_stats(void)
> memset(&ru_stats, 0, sizeof(ru_stats));
> }
>
> -static int prepare_metric(const struct metric_expr *mexp,
> +static bool tool_pmu__is_time_event(const struct perf_stat_config *config,
> + const struct evsel *evsel, int *tool_aggr_idx)
> +{
> + enum tool_pmu_event event = evsel__tool_event(evsel);
> + int aggr_idx;
> +
> + if (event != TOOL_PMU__EVENT_DURATION_TIME &&
> + event != TOOL_PMU__EVENT_USER_TIME &&
> + event != TOOL_PMU__EVENT_SYSTEM_TIME)
> + return false;
> +
> + if (config) {
> + cpu_aggr_map__for_each_idx(aggr_idx, config->aggr_map) {
> + if (config->aggr_map->map[aggr_idx].cpu.cpu == 0) {
> + *tool_aggr_idx = aggr_idx;
> + return true;
> + }
> + }
> + pr_debug("Unexpected CPU0 missing in aggregation for tool event.\n");
> + }
> + *tool_aggr_idx = 0; /* Assume the first aggregation index works. */
> + return true;
> +}
> +
> +static int prepare_metric(struct perf_stat_config *config,
> + const struct metric_expr *mexp,
> const struct evsel *evsel,
> struct expr_parse_ctx *pctx,
> int aggr_idx)
> @@ -36,93 +61,51 @@ static int prepare_metric(const struct metric_expr *mexp,
> int i;
>
> for (i = 0; metric_events[i]; i++) {
> + int source_count = 0, tool_aggr_idx;
> + bool is_tool_time =
> + tool_pmu__is_time_event(config, metric_events[i], &tool_aggr_idx);
> + struct perf_stat_evsel *ps = metric_events[i]->stats;
> + struct perf_stat_aggr *aggr;
> char *n;
> double val;
> - int source_count = 0;
>
> - if (evsel__is_tool(metric_events[i])) {
> - struct stats *stats;
> - double scale;
> -
> - switch (evsel__tool_event(metric_events[i])) {
> - case TOOL_PMU__EVENT_DURATION_TIME:
> - stats = &walltime_nsecs_stats;
> - scale = 1e-9;
> - break;
> - case TOOL_PMU__EVENT_USER_TIME:
> - stats = &ru_stats.ru_utime_usec_stat;
> - scale = 1e-6;
> + /*
> + * If there are multiple uncore PMUs and we're not reading the
> + * leader's stats, determine the stats for the appropriate
> + * uncore PMU.
> + */
> + if (evsel && evsel->metric_leader &&
> + evsel->pmu != evsel->metric_leader->pmu &&
> + mexp->metric_events[i]->pmu == evsel->metric_leader->pmu) {
> + struct evsel *pos;
> +
> + evlist__for_each_entry(evsel->evlist, pos) {
> + if (pos->pmu != evsel->pmu)
> + continue;
> + if (pos->metric_leader != mexp->metric_events[i])
> + continue;
> + ps = pos->stats;
> + source_count = 1;
> break;
> - case TOOL_PMU__EVENT_SYSTEM_TIME:
> - stats = &ru_stats.ru_stime_usec_stat;
> - scale = 1e-6;
> - break;
I think this was broken as it seems to be converted to nsec in the
update_rusage_stats().
> - case TOOL_PMU__EVENT_NONE:
> - pr_err("Invalid tool event 'none'");
> - abort();
> - case TOOL_PMU__EVENT_MAX:
> - pr_err("Invalid tool event 'max'");
> - abort();
> - case TOOL_PMU__EVENT_HAS_PMEM:
> - case TOOL_PMU__EVENT_NUM_CORES:
> - case TOOL_PMU__EVENT_NUM_CPUS:
> - case TOOL_PMU__EVENT_NUM_CPUS_ONLINE:
> - case TOOL_PMU__EVENT_NUM_DIES:
> - case TOOL_PMU__EVENT_NUM_PACKAGES:
> - case TOOL_PMU__EVENT_SLOTS:
> - case TOOL_PMU__EVENT_SMT_ON:
> - case TOOL_PMU__EVENT_SYSTEM_TSC_FREQ:
> - case TOOL_PMU__EVENT_CORE_WIDE:
> - case TOOL_PMU__EVENT_TARGET_CPU:
> - default:
> - pr_err("Unexpected tool event '%s'", evsel__name(metric_events[i]));
> - abort();
> }
> - val = avg_stats(stats) * scale;
> - source_count = 1;
> - } else {
> - struct perf_stat_evsel *ps = metric_events[i]->stats;
> - struct perf_stat_aggr *aggr;
> -
> + }
> + /* 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 there are multiple uncore PMUs and we're not
> - * reading the leader's stats, determine the stats for
> - * the appropriate uncore PMU.
> + * Not supported events will have a count of 0, which
> + * can be confusing in a metric. Explicitly set the
> + * value to NAN. Not counted events (enable time of 0)
> + * are read as 0.
> */
> - if (evsel && evsel->metric_leader &&
> - evsel->pmu != evsel->metric_leader->pmu &&
> - mexp->metric_events[i]->pmu == evsel->metric_leader->pmu) {
> - struct evsel *pos;
> -
> - evlist__for_each_entry(evsel->evlist, pos) {
> - if (pos->pmu != evsel->pmu)
> - continue;
> - if (pos->metric_leader != mexp->metric_events[i])
> - continue;
> - ps = pos->stats;
> - source_count = 1;
> - break;
> - }
> - }
> - aggr = &ps->aggr[aggr_idx];
> - if (!aggr)
> - break;
> -
> - if (!metric_events[i]->supported) {
> - /*
> - * Not supported events will have a count of 0,
> - * which can be confusing in a
> - * metric. Explicitly set the value to NAN. Not
> - * counted events (enable time of 0) are read as
> - * 0.
> - */
> - val = NAN;
> - source_count = 0;
> - } else {
> - val = aggr->counts.val;
> - if (!source_count)
> - source_count = evsel__source_count(metric_events[i]);
> - }
> + val = NAN;
> + source_count = 0;
> + } else {
> + val = aggr->counts.val;
> + if (is_tool_time)
> + val *= 1e-9; /* Convert time event nanoseconds to seconds. */
And this code treats all time events are in nsec now.
Thanks,
Namhyung
> + if (!source_count)
> + source_count = evsel__source_count(metric_events[i]);
> }
> n = strdup(evsel__metric_id(metric_events[i]));
> if (!n)
> @@ -168,7 +151,7 @@ static void generic_metric(struct perf_stat_config *config,
> pctx->sctx.user_requested_cpu_list = strdup(config->user_requested_cpu_list);
> pctx->sctx.runtime = runtime;
> pctx->sctx.system_wide = config->system_wide;
> - i = prepare_metric(mexp, evsel, pctx, aggr_idx);
> + i = prepare_metric(config, mexp, evsel, pctx, aggr_idx);
> if (i < 0) {
> expr__ctx_free(pctx);
> return;
> @@ -229,7 +212,7 @@ double test_generic_metric(struct metric_expr *mexp, int aggr_idx)
> if (!pctx)
> return NAN;
>
> - if (prepare_metric(mexp, /*evsel=*/NULL, pctx, aggr_idx) < 0)
> + if (prepare_metric(/*config=*/NULL, mexp, /*evsel=*/NULL, pctx, aggr_idx) < 0)
> goto out;
>
> if (expr__parse(&ratio, pctx, mexp->metric_expr))
> --
> 2.51.2.1041.gc1ab5b90ca-goog
>
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