perf tool_pmu: Allow num_cpus(_online) to be specific to a cpumask

For hybrid metrics it is useful to know the number of p-core or e-core
CPUs. If a cpumask is specified for the num_cpus or num_cpus_online
tool events, compute the value relative to the given mask rather than
for the full system.

```
$ sudo /tmp/perf/perf stat -e 'tool/num_cpus/,tool/num_cpus,cpu=cpu_core/,
  tool/num_cpus,cpu=cpu_atom/,tool/num_cpus_online/,tool/num_cpus_online,
  cpu=cpu_core/,tool/num_cpus_online,cpu=cpu_atom/' true

 Performance counter stats for 'true':

                28      tool/num_cpus/
                16      tool/num_cpus,cpu=cpu_core/
                12      tool/num_cpus,cpu=cpu_atom/
                28      tool/num_cpus_online/
                16      tool/num_cpus_online,cpu=cpu_core/
                12      tool/num_cpus_online,cpu=cpu_atom/

       0.000767205 seconds time elapsed

       0.000938000 seconds user
       0.000000000 seconds sys
```

Reviewed-by: Thomas Falcon <thomas.falcon@intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250719030517.1990983-6-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index ca70a14c7cdfdad7d01ddbb337c62c55e9edd754..7fda0ff89c168b6bdd9ae1bbc6722c179f912e47 100644 (file)
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -401,7 +401,7 @@ double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx
        if (ev != TOOL_PMU__EVENT_NONE) {
                u64 count;
 
-               if (tool_pmu__read_event(ev, &count))
+               if (tool_pmu__read_event(ev, /*evsel=*/NULL, &count))
                        result = count;
                else
                        pr_err("Failure to read '%s'", literal);

diff --git a/tools/perf/util/tool_pmu.c b/tools/perf/util/tool_pmu.c
index 4630b8cc8e52934f9f26357d65601efffaeb10ce..7aa4f315b0ac21c4c09a8a83db4d31830d651c2d 100644 (file)
--- a/tools/perf/util/tool_pmu.c
+++ b/tools/perf/util/tool_pmu.c
@@ -332,7 +332,7 @@ static bool has_pmem(void)
        return has_pmem;
 }
 
-bool tool_pmu__read_event(enum tool_pmu_event ev, u64 *result)
+bool tool_pmu__read_event(enum tool_pmu_event ev, struct evsel *evsel, u64 *result)
 {
        const struct cpu_topology *topology;
 
@@ -347,18 +347,60 @@ bool tool_pmu__read_event(enum tool_pmu_event ev, u64 *result)
                return true;
 
        case TOOL_PMU__EVENT_NUM_CPUS:
-               *result = cpu__max_present_cpu().cpu;
+               if (!evsel || perf_cpu_map__is_empty(evsel->core.cpus)) {
+                       /* No evsel to be specific to. */
+                       *result = cpu__max_present_cpu().cpu;
+               } else if (!perf_cpu_map__has_any_cpu(evsel->core.cpus)) {
+                       /* Evsel just has specific CPUs. */
+                       *result = perf_cpu_map__nr(evsel->core.cpus);
+               } else {
+                       /*
+                        * "Any CPU" event that can be scheduled on any CPU in
+                        * the PMU's cpumask. The PMU cpumask should be saved in
+                        * own_cpus. If not present fall back to max.
+                        */
+                       if (!perf_cpu_map__is_empty(evsel->core.own_cpus))
+                               *result = perf_cpu_map__nr(evsel->core.own_cpus);
+                       else
+                               *result = cpu__max_present_cpu().cpu;
+               }
                return true;
 
        case TOOL_PMU__EVENT_NUM_CPUS_ONLINE: {
                struct perf_cpu_map *online = cpu_map__online();
 
-               if (online) {
+               if (!online)
+                       return false;
+
+               if (!evsel || perf_cpu_map__is_empty(evsel->core.cpus)) {
+                       /* No evsel to be specific to. */
                        *result = perf_cpu_map__nr(online);
-                       perf_cpu_map__put(online);
-                       return true;
+               } else if (!perf_cpu_map__has_any_cpu(evsel->core.cpus)) {
+                       /* Evsel just has specific CPUs. */
+                       struct perf_cpu_map *tmp =
+                               perf_cpu_map__intersect(online, evsel->core.cpus);
+
+                       *result = perf_cpu_map__nr(tmp);
+                       perf_cpu_map__put(tmp);
+               } else {
+                       /*
+                        * "Any CPU" event that can be scheduled on any CPU in
+                        * the PMU's cpumask. The PMU cpumask should be saved in
+                        * own_cpus, if not present then just the online cpu
+                        * mask.
+                        */
+                       if (!perf_cpu_map__is_empty(evsel->core.own_cpus)) {
+                               struct perf_cpu_map *tmp =
+                                       perf_cpu_map__intersect(online, evsel->core.own_cpus);
+
+                               *result = perf_cpu_map__nr(tmp);
+                               perf_cpu_map__put(tmp);
+                       } else {
+                               *result = perf_cpu_map__nr(online);
+                       }
                }
-               return false;
+               perf_cpu_map__put(online);
+               return true;
        }
        case TOOL_PMU__EVENT_NUM_DIES:
                topology = online_topology();
@@ -417,7 +459,7 @@ int evsel__tool_pmu_read(struct evsel *evsel, int cpu_map_idx, int thread)
                        old_count = perf_counts(evsel->prev_raw_counts, cpu_map_idx, thread);
                val = 0;
                if (cpu_map_idx == 0 && thread == 0) {
-                       if (!tool_pmu__read_event(ev, &val)) {
+                       if (!tool_pmu__read_event(ev, evsel, &val)) {
                                count->lost++;
                                val = 0;
                        }

diff --git a/tools/perf/util/tool_pmu.h b/tools/perf/util/tool_pmu.h
index c6ad1dd90a56d48bab3191f9e37b92052f7a608a..d642e7d73910ece726b94a127ec6b01a967fe4db 100644 (file)
--- a/tools/perf/util/tool_pmu.h
+++ b/tools/perf/util/tool_pmu.h
@@ -34,7 +34,7 @@ enum tool_pmu_event tool_pmu__str_to_event(const char *str);
 bool tool_pmu__skip_event(const char *name);
 int tool_pmu__num_skip_events(void);
 
-bool tool_pmu__read_event(enum tool_pmu_event ev, u64 *result);
+bool tool_pmu__read_event(enum tool_pmu_event ev, struct evsel *evsel, u64 *result);
 
 u64 tool_pmu__cpu_slots_per_cycle(void);