linux-kernel - Re: [PATCH v1 0/3] Parse event sort/regroup fixes

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Message-ID: <CAP-5=fWXd8KhvxnPjjFjtybNZ7BsN6n_55xFaEA_-Jda0g2+XQ@mail.gmail.com>
Date:   Mon, 24 Jul 2023 08:24:42 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 0/3] Parse event sort/regroup fixes

On Wed, Jul 19, 2023 at 7:49 AM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> Em Tue, Jul 18, 2023 at 05:18:33PM -0700, Ian Rogers escreveu:
> > Patch 1, fix:
> > perf stat -e cycles,slots,topdown-fe-bound
> > so that cycles isn't made a group leader (failure caused by PMUs
> > matching). Previously this event list would fail so not necessarily a
> > regression over previous perf release.
> >
> > Patch 2, when regrouping events the leader needs to be updated due to
> > sorting. This fix causes larger event groups that then regress at
> > least the tigerlake metric test as the kernel PMU driver fails to
> > break the weak groups. This is a fix for a bug but the consequence of
> > fixing the bug is to make a passing test fail due to the kernel PMU
> > driver.
> >
> > Patch 3, don't alter the list position of events without a group if
> > they don't need forcing into a group. Analysis showed this was the
> > cause of the issue reported by Andi Kleen:
> > https://lore.kernel.org/linux-perf-users/ZLBgbHkbrfGygM%2Fu@tassilo/
>
> Andi,
>
>         Can you please check these patches and provide a Tested-by?

I think we should be aiming to get these fixes/changes into Linux 6.5
and it's a shame this didn't happen last week. Feedback appreciated.

Thanks,
Ian

> Thanks,
>
> - Arnaldo
>
> > Due to the test regression in patch 2, follow up patches may be
> > necessary for Icelake+ Intel vendor metrics to add METRIC_NO_GROUP to
> > avoid the kernel PMU driver issue.
> >
> > Ian Rogers (3):
> >   perf parse-events: Extra care around force grouped events
> >   perf parse-events: When fixing group leaders always set the leader
> >   perf parse-events: Only move force grouped evsels when sorting
> >
> >  tools/perf/util/parse-events.c | 58 +++++++++++++++++++++-------------
> >  1 file changed, 36 insertions(+), 22 deletions(-)
> >
> > --
> > 2.41.0.487.g6d72f3e995-goog