Re: [PATCH 1/8] perf tools: Add fallback for exclude_guest

[Ian Rogers]

On Mon, Sep 30, 2024 at 5:20 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> Commit 7b100989b4f6bce70 ("perf evlist: Remove __evlist__add_default")
> changed to parse "cycles:P" event instead of creating a new cycles
> event for perf record.  But it also changed the way how modifiers are
> handled so it doesn't set the exclude_guest bit by default.
>
> It seems Apple M1 PMU requires exclude_guest set and returns EOPNOTSUPP
> if not.  Let's add a fallback so that it can work with default events.
>
> Fixes: 7b100989b4f6bce70 ("perf evlist: Remove __evlist__add_default")
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: James Clark <james.clark@xxxxxxxxxx>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/builtin-stat.c | 18 +++++++++++++++---
>  tools/perf/util/evsel.c   | 21 +++++++++++++++++++++
>  2 files changed, 36 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 1521b6df26065ccf..fd9ea15f6b1c0809 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -639,8 +639,7 @@ static enum counter_recovery stat_handle_error(struct evsel *counter)
>          * (behavior changed with commit b0a873e).
>          */
>         if (errno == EINVAL || errno == ENOSYS ||
> -           errno == ENOENT || errno == EOPNOTSUPP ||
> -           errno == ENXIO) {
> +           errno == ENOENT || errno == ENXIO) {
>                 if (verbose > 0)
>                         ui__warning("%s event is not supported by the kernel.\n",
>                                     evsel__name(counter));
> @@ -658,7 +657,7 @@ static enum counter_recovery stat_handle_error(struct evsel *counter)
>                 if (verbose > 0)
>                         ui__warning("%s\n", msg);
>                 return COUNTER_RETRY;
> -       } else if (target__has_per_thread(&target) &&
> +       } else if (target__has_per_thread(&target) && errno != EOPNOTSUPP &&
>                    evsel_list->core.threads &&
>                    evsel_list->core.threads->err_thread != -1) {
>                 /*
> @@ -679,6 +678,19 @@ static enum counter_recovery stat_handle_error(struct evsel *counter)
>                 return COUNTER_SKIP;
>         }
>
> +       if (errno == EOPNOTSUPP) {
> +               if (verbose > 0) {
> +                       ui__warning("%s event is not supported by the kernel.\n",
> +                                   evsel__name(counter));
> +               }
> +               counter->supported = false;
> +               counter->errored = true;
> +
> +               if ((evsel__leader(counter) != counter) ||
> +                   !(counter->core.leader->nr_members > 1))
> +                       return COUNTER_SKIP;
> +       }
> +
>         evsel__open_strerror(counter, &target, errno, msg, sizeof(msg));
>         ui__error("%s\n", msg);
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index da0bada62140d9b0..0ddd77c139e89a2e 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -3259,6 +3259,27 @@ bool evsel__fallback(struct evsel *evsel, struct target *target, int err,
>                 evsel->core.attr.exclude_kernel = 1;
>                 evsel->core.attr.exclude_hv     = 1;
>
> +               return true;
> +       } else if (err == EOPNOTSUPP && !evsel->core.attr.exclude_guest &&
> +                  !evsel->exclude_GH) {
> +               const char *name = evsel__name(evsel);
> +               char *new_name;
> +               const char *sep = ":";
> +
> +               /* Is there already the separator in the name. */
> +               if (strchr(name, '/') ||
> +                   (strchr(name, ':') && !evsel->is_libpfm_event))
> +                       sep = "";
> +
> +               if (asprintf(&new_name, "%s%sH", name, sep) < 0)
> +                       return false;
> +
> +               free(evsel->name);
> +               evsel->name = new_name;
> +               /* Apple M1 requires exclude_guest */
> +               scnprintf(msg, msgsize, "trying to fall back to excluding guest samples");
> +               evsel->core.attr.exclude_guest = 1;
> +
>                 return true;
>         }
>
> --
> 2.46.1.824.gd892dcdcdd-goog
>