Re: [PATCH RFC 18/21] libperf evlist: Allow mixing per-thread and per-cpu mmaps

[Namhyung Kim]

On Fri, Apr 22, 2022 at 9:25 AM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> mmap_per_evsel() will skip events that do not match the CPU, so all CPUs
> can be iterated in any case.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
[...]
> @@ -561,9 +538,12 @@ static int perf_evlist__nr_mmaps(struct perf_evlist *evlist)
>  {
>         int nr_mmaps;
>
> +       /* One for each CPU */
>         nr_mmaps = perf_cpu_map__nr(evlist->all_cpus);
> -       if (perf_cpu_map__empty(evlist->all_cpus))
> -               nr_mmaps = perf_thread_map__nr(evlist->threads);
> +       /* One for each thread */
> +       nr_mmaps += perf_thread_map__nr(evlist->threads);
> +       /* Minus the dummy CPU or dummy thread */
> +       nr_mmaps -= 1;

I'm not sure it'd work for per-task events with default-per-cpu mode.

Thanks,
Namhyung

>
>         return nr_mmaps;
>  }