linux-kernel - Re: [PATCH v2 06/18] perf s390 s390_cpumcfdg

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Message-ID: <CAP-5=fUshGTWjcVVBACGToDziK5s1kgpxpnraicwQGZAfzvabg@mail.gmail.com>
Date:   Fri, 25 Aug 2023 23:28:19 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Thomas Richter <tmricht@...ux.ibm.com>,
        Sumanth Korikkar <sumanthk@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Jiri Olsa <jolsa@...nel.org>,
        James Clark <james.clark@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/18] perf s390 s390_cpumcfdg_dump: Don't scan all PMUs

On Fri, Aug 25, 2023 at 6:38 PM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> Em Fri, Aug 25, 2023 at 03:56:54PM -0700, Ian Rogers escreveu:
> > On Fri, Aug 25, 2023 at 1:56 PM Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
> > > [root@...nelqe3 linux]# git bisect bad
> > > 2e255b4f9f41f137d9e3dc4fae3603a9c2c3dd28 is the first bad commit
> > > commit 2e255b4f9f41f137d9e3dc4fae3603a9c2c3dd28
> > > Author: Ian Rogers <irogers@...gle.com>
> > > Date:   Wed Aug 23 21:13:16 2023 -0700
> > >
> > >     perf jevents: Group events by PMU
> > >
> > >     Prior to this change a cpuid would map to a list of events where the PMU
> > >     would be encoded alongside the event information. This change breaks
> > >     apart each group of events so that there is a group per PMU. A new table
> > >     is added with the PMU's name and the list of events, the original table
> > >     now holding an array of these per PMU tables.
> > >
> > >     These changes are to make it easier to get per PMU information about
> > >     events, rather than the current approach of scanning all events. The
> > >     perf binary size with BPF skeletons on x86 is reduced by about 1%. The
> > >     unidentified PMU is now always expanded to "cpu".
> > >
> > >     Signed-off-by: Ian Rogers <irogers@...gle.com>
> > >     Cc: Adrian Hunter <adrian.hunter@...el.com>
> > >     Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> > >     Cc: Gaosheng Cui <cuigaosheng1@...wei.com>
> > >     Cc: Ingo Molnar <mingo@...hat.com>
> > >     Cc: James Clark <james.clark@....com>
> > >     Cc: Jing Zhang <renyu.zj@...ux.alibaba.com>
> > >     Cc: Jiri Olsa <jolsa@...nel.org>
> > >     Cc: John Garry <john.g.garry@...cle.com>
> > >     Cc: Kajol Jain <kjain@...ux.ibm.com>
> > >     Cc: Kan Liang <kan.liang@...ux.intel.com>
> > >     Cc: Mark Rutland <mark.rutland@....com>
> > >     Cc: Namhyung Kim <namhyung@...nel.org>
> > >     Cc: Peter Zijlstra <peterz@...radead.org>
> > >     Cc: Ravi Bangoria <ravi.bangoria@....com>
> > >     Cc: Rob Herring <robh@...nel.org>
> > >     Link: https://lore.kernel.org/r/20230824041330.266337-5-irogers@google.com
> > >     Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > >
> > >  tools/perf/pmu-events/jevents.py | 181 +++++++++++++++++++++++++++++----------
> > >  tools/perf/tests/pmu-events.c    |  30 ++++---
> > >  2 files changed, 154 insertions(+), 57 deletions(-)
> > > [root@...nelqe3 linux]#
> >
> > This change defaulted events without a specified PMU to being for the
> > PMU 'cpu', so that events in pmu-events.c were associated with a PMU
> > and we could find per-PMU information easily. The test events have no
> > PMU and so this has broken s390 where the the PMU should be "cpum_cf".
> > It has probably also broken x86 hybrid and arm where their default PMU
> > isn't cpu. I'll work on a fix, but the problem will be limited to the
> > test.
>
> Ok, please use tmp.perf-tools-next as the basis for your work, that is
> what I have right now.

Thanks. I repro-ed the PMU events failure on alderlake and the patch I sent:
https://lore.kernel.org/lkml/20230826062203.1058041-1-irogers@google.com/
addressed it. I didn't repro the sysfs issue and so it may be resolved
by this too, but it may be a different issue. There may also be more
issues specific to s390. I'm hopeful the patch fixes them but please
give it a go.

Thanks,
Ian

> - Arnaldo