linux-kernel - Re: [PATCH v2 0/4] Enable display of partial and empty SVE predicates from Arm SPE data

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Message-ID: <CAP-5=fUz_u8BODDn3OK5hh9xSbXbMZU0fiCJUdpoS3AFQGQ9GA@mail.gmail.com>
Date:   Mon, 20 Mar 2023 10:50:59 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     James Clark <james.clark@....com>
Cc:     linux-perf-users@...r.kernel.org, Anshuman.Khandual@....com,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        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>,
        John Garry <john.g.garry@...cle.com>,
        Will Deacon <will@...nel.org>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 0/4] Enable display of partial and empty SVE predicates
 from Arm SPE data

On Mon, Mar 20, 2023 at 8:15 AM James Clark <james.clark@....com> wrote:
>
> Changes since v1:
>  * Rebase onto perf/core because it no longer applied cleanly
>
> ------------
>
> Hi,
>
> I'm submitting this on behalf of German who moved on to work on other
> things in Arm before he could finish it off.
>
> The predicate information is available on SPE samples from
> Armv8.3 (FEAT_SPEv1p1), this could be useful info for profiling SVE
> code as partial and empty predicates indicate that the full vector
> width isn't being used. There is a good example in the last commit
> message.
>
> Though currently, there isn't a suitable field to store the info
> on Perf samples, so this change also adds a new SIMD field.
> This field could be used by other architectures, but currently there
> is only one bit reserved to identify SVE. It's only added to
> struct perf_sample on the userspace side, and isn't part of the kernel
> ABI, so it doesn't survive a perf inject. Although this is the
> same behavior for some other fields like branch flags, so I don't
> think it should be an issue to do something similar here. Perhaps in
> the future we could make sure everything that is synthesised from
> auxtrace data also makes it back into the new Perf inject file without
> being lost.

Series:
Acked-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> German Gomez (4):
>   perf event: Add simd_flags field to perf_sample
>   perf arm-spe: Refactor arm-spe to support operation packet type
>   perf arm-spe: Add SVE flags to the SPE samples
>   perf report: Add 'simd' sort field
>
>  tools/perf/Documentation/perf-report.txt      |  1 +
>  .../util/arm-spe-decoder/arm-spe-decoder.c    | 30 ++++++++++--
>  .../util/arm-spe-decoder/arm-spe-decoder.h    | 47 +++++++++++++++----
>  tools/perf/util/arm-spe.c                     | 28 +++++++++--
>  tools/perf/util/hist.c                        |  1 +
>  tools/perf/util/hist.h                        |  1 +
>  tools/perf/util/sample.h                      | 13 +++++
>  tools/perf/util/sort.c                        | 47 +++++++++++++++++++
>  tools/perf/util/sort.h                        |  2 +
>  9 files changed, 152 insertions(+), 18 deletions(-)
>
>
> base-commit: 96d541699e5c50b1bc2d50c83cd7145994d5f071
> --
> 2.34.1
>