linux-kernel - Re: [PATCH v5 0/3] perf stat affinity changes

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Message-ID: <CAP-5=fXk=zaqgfqWQtJGyKj=6+14ZsxxsQra+eax4DzvKD2qeg@mail.gmail.com>
Date: Fri, 2 Jan 2026 07:26:29 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Dr. David Alan Gilbert" <linux@...blig.org>, Yang Li <yang.lee@...ux.alibaba.com>, 
	James Clark <james.clark@...aro.org>, Thomas Falcon <thomas.falcon@...el.com>, 
	Thomas Richter <tmricht@...ux.ibm.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: Re: [PATCH v5 0/3] perf stat affinity changes

On Tue, Nov 18, 2025 at 1:13 PM Ian Rogers <irogers@...gle.com> wrote:
>
> The remnants of:
> https://lore.kernel.org/lkml/20251113180517.44096-1-irogers@google.com/
>
> Read tool events last so that counts shouldn't exceed theoretic
> maximums.
>
> Change how affinities work with evlist__for_each_cpu. Move the
> affinity code into the iterator to simplify setting it up. Detect when
> affinities will and won't be profitable, for example a tool event and
> a regular perf event (or read group) may face less delay from a single
> IPI for the event read than from a call to sched_setaffinity. Add a
>  --no-affinity flag to perf stat to allow affinities to be disabled.

Ping.

Thanks,
Ian

> v5: Drop merged changes. Move tool event reading to first
>     patch. Change --no-affinity flag to --affinity/--no-affinity flag.
>
> v4: Rebase. Add patch to reduce scope of walltime_nsec_stats now that
>     the legacy metric code is no more. Minor tweak to the ru_stats
>     clean up.
> https://lore.kernel.org/lkml/20251113180517.44096-1-irogers@google.com/
>
> v3: Add affinity clean ups and read tool events last.
> https://lore.kernel.org/lkml/20251106071241.141234-1-irogers@google.com/
>
> v2: Fixed an aggregation index issue:
> https://lore.kernel.org/lkml/20251104234148.3103176-2-irogers@google.com/
>
> v1:
> https://lore.kernel.org/lkml/20251104053449.1208800-1-irogers@google.com/
>
> Ian Rogers (3):
>   perf stat: Read tool events last
>   perf evlist: Reduce affinity use and move into iterator, fix no
>     affinity
>   perf stat: Add no-affinity flag
>
>  tools/perf/Documentation/perf-stat.txt |   4 +
>  tools/perf/builtin-stat.c              | 159 ++++++++++++++-----------
>  tools/perf/util/evlist.c               | 156 ++++++++++++++----------
>  tools/perf/util/evlist.h               |  27 +++--
>  tools/perf/util/pmu.c                  |  12 ++
>  tools/perf/util/pmu.h                  |   1 +
>  6 files changed, 222 insertions(+), 137 deletions(-)
>
> --
> 2.52.0.rc1.455.g30608eb744-goog
>