linux-kernel - Re: [PATCH v4 00/16] Intel TPEBS min/max/mean/last support

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Message-ID: <Z_mhEc5GAWM5cUTh@z2>
Date: Fri, 11 Apr 2025 16:09:05 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: 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>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Weilin Wang <weilin.wang@...el.com>,
	James Clark <james.clark@...aro.org>, Xu Yang <xu.yang_2@....com>,
	John Garry <john.g.garry@...cle.com>,
	Howard Chu <howardchu95@...il.com>, Levi Yun <yeoreum.yun@....com>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 00/16] Intel TPEBS min/max/mean/last support

On Tue, Apr 08, 2025 at 11:10:27PM -0700, Ian Rogers wrote:
> The patches add support to computing the min, max, mean or last
> retirement latency and then using that value as the basis for metrics.
> When values aren't available, support is added to use the retirement
> latency as recorded for an event in the perf json.
> 
> Support is added for reading the retirement latency from the forked
> perf command more than once. To avoid killing the process commands are
> sent through the control fd. Some name handling is changed to make it
> more robust.
> 
> Rather than retirement latency events having issues with perf record,
> make it so that the retirement latency modifier enables sample
> weights.
> 
> v4: Don't use json min/max in retirement latency stats as they will
>     never update afterwards. Warn once if json data is used when TPEBS
>     recording was requested.
> 
> v3: Two fixes from Kan Liang. Ensure min/max statistics don't vary
>     when real samples are encountered.
> 
> v2: Addition of header cleanup patch originally posted:
>     https://lore.kernel.org/lkml/20241210191823.612631-1-irogers@google.com/
>     as there are no arch specific reasons not to build this code.
>     Fix bug in "perf pmu-events: Add retirement latency to JSON events
>     inside of perf" where "t->stats.n != 0" should have been
>     "t->stats.n == 0".
>     Add patch so that perf record of a retirement latency event
>     doesn't crash but instead enables sample weights for the event.
> 
> Ian Rogers (16):
>   perf intel-tpebs: Cleanup header
>   perf intel-tpebs: Simplify tpebs_cmd
>   perf intel-tpebs: Rename tpebs_start to evsel__tpebs_open
>   perf intel-tpebs: Separate evsel__tpebs_prepare out of
>     evsel__tpebs_open
>   perf intel-tpebs: Move cpumap_buf out of evsel__tpebs_open
>   perf intel-tpebs: Reduce scope of tpebs_events_size
>   perf intel-tpebs: Inline get_perf_record_args
>   perf intel-tpebs: Ensure events are opened, factor out finding
>   perf intel-tpebs: Refactor tpebs_results list
>   perf intel-tpebs: Add support for updating counts in evsel__tpebs_read
>   perf intel-tpebs: Add mutex for tpebs_results
>   perf intel-tpebs: Don't close record on read
>   perf intel-tpebs: Use stats for retirement latency statistics
>   perf stat: Add mean, min, max and last --tpebs-mode options
>   perf pmu-events: Add retirement latency to JSON events inside of perf
>   perf record: Retirement latency cleanup in evsel__config

I have a nitpick but otherwise looks good to me.

Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung

> 
>  tools/perf/Documentation/perf-stat.txt   |   7 +
>  tools/perf/builtin-stat.c                |  29 +-
>  tools/perf/pmu-events/empty-pmu-events.c | 216 +++----
>  tools/perf/pmu-events/jevents.py         |   6 +
>  tools/perf/pmu-events/pmu-events.h       |   3 +
>  tools/perf/util/Build                    |   2 +-
>  tools/perf/util/evlist.c                 |   1 -
>  tools/perf/util/evsel.c                  |  22 +-
>  tools/perf/util/evsel.h                  |   6 +
>  tools/perf/util/intel-tpebs.c            | 682 ++++++++++++++---------
>  tools/perf/util/intel-tpebs.h            |  40 +-
>  tools/perf/util/parse-events.c           |   4 +
>  tools/perf/util/pmu.c                    |  52 +-
>  tools/perf/util/pmu.h                    |   3 +
>  14 files changed, 666 insertions(+), 407 deletions(-)
> 
> -- 
> 2.49.0.504.g3bcea36a83-goog
>