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Message-ID: <ZvsLu7-avQHVvp7c@google.com>
Date: Mon, 30 Sep 2024 13:36:11 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: "Liang, Kan" <kan.liang@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org,
Ravi Bangoria <ravi.bangoria@....com>,
Mark Rutland <mark.rutland@....com>,
James Clark <james.clark@....com>, Kajol Jain <kjain@...ux.ibm.com>,
Thomas Richter <tmricht@...ux.ibm.com>,
Atish Patra <atishp@...shpatra.org>,
Palmer Dabbelt <palmer@...osinc.com>,
Mingwei Zhang <mizhang@...gle.com>,
James Clark <james.clark@...aro.org>
Subject: Re: [PATCH 01/10] perf tools: Add fallback for exclude_guest
On Fri, Sep 06, 2024 at 09:47:53AM -0400, Liang, Kan wrote:
>
>
> On 2024-09-05 4:24 p.m., Namhyung Kim 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@....com>
> > Cc: James Clark <james.clark@...aro.org>
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> > tools/perf/builtin-stat.c | 3 +--
> > tools/perf/util/evsel.c | 21 +++++++++++++++++++++
> > 2 files changed, 22 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index cf985cdb9a6ee588..d8315dae930184ba 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));
>
> It seems the behavior for other reasons which trigger the 'EOPNOTSUPP'
> is changed as well.
> At least, it looks like we don't skip the member event with EOPNOTSUPP
> anymore.
>
> I'm not sure if it's a big deal. But I think we'd better mention it in
> the change log or the comments.
Yeah I think it should handle EOPNOTSUPP at the end of the function to
maintain the behavior. Still it's not exactly the same but I think the
skippable case is ok. Thanks for pointing this out.
Thanks,
Namhyung
>
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index 49cc71511c0c8ce8..d59ad76b28758906 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -3244,6 +3244,27 @@ 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;
> > }
> >
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