Re: [PATCH v7 0/6] perf stat affinity changes

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Fri, Feb 06, 2026 at 02:01:37PM -0800, Ian Rogers wrote:
> On Fri, Feb 6, 2026 at 1:35 PM Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> >
> > On Tue, Feb 03, 2026 at 02:51:23PM -0800, Ian Rogers wrote:
> > > 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.
> > >
> > > v7: Revert "perf tool_pmu: More accurately set the cpus for tool
> > >     events" that caused issues with user specified CPUs (Andres Freund
> > >     <andres@anarazel.de>). Fix a null test is prepare_metric so that
> > >     missing events can't trigger segfaults (Andres Freund). Make the
> > >     CPU map propagation improve the CPU maps for tool events that only
> > >     read on index 0, this allows later setting when
> > >     evlist__create_maps is called with the correct user CPUs. Rebase
> > >     previous non-merged affinity changes that hadn't been picked up
> > >     yet.
> >
> > Not applying to tmp.perf-tools-next, can you please check?
> 
> Will send a rebase on tmp.perf-tools-next shortly.

Thanks!

> Could I interest you in some second servings of build improvements
> while you wait? :-)
> https://lore.kernel.org/lkml/20260203164323.3447826-1-irogers@google.com/

Applied it locally for testing,

- Arnaldo
 
> Thanks,
> Ian
> 
> > - Arnaldo
> >
> > > v6: Drop merged tool event change. Move TPEBS fix into its own patch
> > >     1st.
> > > https://lore.kernel.org/lkml/20260108212652.768875-1-irogers@google.com/
> > >
> > > v5: Drop merged changes. Move tool event reading to first
> > >     patch. Change --no-affinity flag to --affinity/--no-affinity flag.
> > > https://lore.kernel.org/lkml/20251118211326.1840989-1-irogers@google.com/
> > >     On v5 there was discussion with Andi Kleen who points out that
> > >     affinities will work better with real time priorities but using
> > >     this requires privileges.
> > >
> > > 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 (6):
> > >   Revert "perf tool_pmu: More accurately set the cpus for tool events"
> > >   perf stat-shadow: In prepare_metric fix guard on reading NULL
> > >     perf_stat_evsel
> > >   perf evlist: Special map propagation for tool events that read on 1
> > >     CPU
> > >   perf evlist: Missing TPEBS close in evlist__close
> > >   perf evlist: Reduce affinity use and move into iterator, fix no
> > >     affinity
> > >   perf stat: Add no-affinity flag
> > >
> > >  tools/lib/perf/evlist.c                 |  36 +++++-
> > >  tools/lib/perf/include/internal/evsel.h |   2 +
> > >  tools/perf/Documentation/perf-stat.txt  |   4 +
> > >  tools/perf/builtin-stat.c               | 114 ++++++++---------
> > >  tools/perf/util/evlist.c                | 156 +++++++++++++++---------
> > >  tools/perf/util/evlist.h                |  27 ++--
> > >  tools/perf/util/parse-events.c          |  10 +-
> > >  tools/perf/util/pmu.c                   |  23 ++++
> > >  tools/perf/util/pmu.h                   |   3 +
> > >  tools/perf/util/stat-shadow.c           |   7 +-
> > >  tools/perf/util/tool_pmu.c              |  19 ---
> > >  tools/perf/util/tool_pmu.h              |   1 -
> > >  12 files changed, 237 insertions(+), 165 deletions(-)
> > >
> > > --
> > > 2.53.0.rc2.204.g2597b5adb4-goog