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