Re: [PATCH] perf top: Use evsel's cpus to replace user_requested_cpus

[Ian Rogers]

On Fri, Dec 8, 2023 at 1:09 PM <kan.liang@xxxxxxxxxxxxxxx> wrote:
>
> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>
> perf top errors out on a hybrid machine
>  $perf top
>
>  Error:
>  The cycles:P event is not supported.
>
> The user_requested_cpus may contain CPUs that are invalid for a hybrid
> PMU. It causes perf_event_open to fail.
>
> The commit ef91871c960e ("perf evlist: Propagate user CPU maps
> intersecting core PMU maps") already intersect the requested CPU map
> with the CPU map of the PMU. Use the evsel's cpus to replace
> user_requested_cpus.
>
> The evlist's threads is also propagated to evsel's threads in
> __perf_evlist__propagate_maps(). Replace it as well.
>
> Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-perf-users/ZXNnDrGKXbEELMXV@xxxxxxxxxx/
> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

Sorry I missed top doing the evlist__create_maps calls:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/builtin-top.c?h=perf-tools-next#n1761
so it is right that the only divergence from record:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/builtin-record.c?h=perf-tools-next#n1362
and stat:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/stat.c?h=perf-tools-next#n797
So this is the right fix I believe.

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/builtin-top.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index ea8c7eca5eee..cce9350177e2 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -1027,8 +1027,8 @@ static int perf_top__start_counters(struct perf_top *top)
>
>         evlist__for_each_entry(evlist, counter) {
>  try_again:
> -               if (evsel__open(counter, top->evlist->core.user_requested_cpus,
> -                                    top->evlist->core.threads) < 0) {
> +               if (evsel__open(counter, counter->core.cpus,
> +                               counter->core.threads) < 0) {
>
>                         /*
>                          * Specially handle overwrite fall back.
> --
> 2.35.1
>