Re: [PATCH v5 10/15] perf jevents: Generate metrics and events as separate tables

[John Garry]

On 26/01/2023 23:36, Ian Rogers wrote:
@@ -660,7 +763,29 @@ const struct pmu_events_table 
*perf_pmu__find_events_table(struct perf_pmu *pmu)
  
  const struct pmu_metrics_table *perf_pmu__find_metrics_table(struct perf_pmu *pmu)
  {
-        return (struct pmu_metrics_table *)perf_pmu__find_events_table(pmu);
+        const struct pmu_metrics_table *table = NULL;
+        char *cpuid = perf_pmu__getcpuid(pmu);
+        int i;
+
+        /* on some platforms which uses cpus map, cpuid can be NULL for
+         * PMUs other than CORE PMUs.
+         */
+        if (!cpuid)
+                return NULL;
+
+        i = 0;
+        for (;;) {
+                const struct pmu_events_map *map = &pmu_events_map[i++];
+                if (!map->arch)
+                        break;
+
+                if (!strcmp_cpuid_str(map->cpuid, cpuid)) {
+                        table = &map->metric_table;
+                        break;
+                }
+        }
+        free(cpuid);
+        return table;
  }

This is almost identical to generated perf_pmu__find_events_table(), 
except we return a pmu_metrics_table * (instead of a pmu_events_table *) 
and also return the metric table member (instead of event table). But 
the definitions are:

/* Struct used to make the PMU event table implementation opaque to 
callers. */
struct pmu_events_table {
        const struct compact_pmu_event *entries;
        size_t length;
};

/* Struct used to make the PMU metric table implementation opaque to 
callers. */
struct pmu_metrics_table {
        const struct compact_pmu_event *entries;
        size_t length;
};

Those structs are defined to be the same thing, so I am failing to see 
the point in a) separate structure types b) why so much duplication

As for b), I know that they are generated and the python code may be 
simpler this way (is it?), but still...

Thanks,
John