linux-kernel - Re: [PATCH v1 00/12] CPU mask improvements/fixes particularly for hybrid

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Message-ID: <9c9d0fc0e37425961f539f8aac6ff09a8da8b503.camel@intel.com>
Date: Wed, 16 Jul 2025 20:03:50 +0000
From: "Falcon, Thomas" <thomas.falcon@...el.com>
To: "ben.gainey@....com" <ben.gainey@....com>,
	"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
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Subject: Re: [PATCH v1 00/12] CPU mask improvements/fixes particularly for
 hybrid

On Tue, 2025-07-15 at 12:55 -0700, Ian Rogers wrote:
> On Fri, Jun 27, 2025 at 12:24 PM Ian Rogers <irogers@...gle.com> wrote:
> > 
> > On hybrid systems some PMUs apply to all core types, particularly for
> > metrics the msr PMU and the tsc event. The metrics often only want the
> > values of the counter for their specific core type. These patches
> > allow the cpu term in an event to give a PMU name to take the cpumask
> > from. For example:
> > 
> >   $ perf stat -e msr/tsc,cpu=cpu_atom/ ...
> > 
> > will aggregate the msr/tsc/ value but only for atom cores. In doing
> > this problems were identified in how cpumasks are handled by parsing
> > and event setup when cpumasks are specified along with a task to
> > profile. The event parsing, cpumask evlist propagation code and perf
> > stat code are updated accordingly.
> > 
> > The final result of the patch series is to be able to run:
> > ```
> > $ perf stat --no-scale -e 'msr/tsc/,msr/tsc,cpu=cpu_core/,msr/tsc,cpu=cpu_atom/' perf test -F 10
> >  10.1: Basic parsing test                                            : Ok
> >  10.2: Parsing without PMU name                                      : Ok
> >  10.3: Parsing with PMU name                                         : Ok
> > 
> >  Performance counter stats for 'perf test -F 10':
> > 
> >         63,704,975      msr/tsc/
> >         47,060,704      msr/tsc,cpu=cpu_core/                        (4.62%)
> >         16,640,591      msr/tsc,cpu=cpu_atom/                        (2.18%)
> > ```
> > 
> > This has (further) identified a kernel bug for task events around the
> > enabled time being too large leading to invalid scaling (hence the
> >  --no-scale in the command line above).
> > 
> > Ian Rogers (12):
> >   perf parse-events: Warn if a cpu term is unsupported by a CPU
> >   perf stat: Avoid buffer overflow to the aggregation map
> >   perf stat: Don't size aggregation ids from user_requested_cpus
> >   perf parse-events: Allow the cpu term to be a PMU
> >   perf tool_pmu: Allow num_cpus(_online) to be specific to a cpumask
> >   libperf evsel: Rename own_cpus to pmu_cpus
> >   libperf evsel: Factor perf_evsel__exit out of perf_evsel__delete
> >   perf evsel: Use libperf perf_evsel__exit
> >   perf pmus: Factor perf_pmus__find_by_attr out of evsel__find_pmu
> >   perf parse-events: Minor __add_event refactoring
> >   perf evsel: Add evsel__open_per_cpu_and_thread
> >   perf parse-events: Support user CPUs mixed with threads/processes
> 
> Ping.

Hi Ian,

Looks good to me.

Reviewed-by: Thomas Falcon <thomas.falcon@...el.com>

Thanks,
Tom

> 
> Thanks,
> Ian
> 
> >  tools/lib/perf/evlist.c                 | 118 ++++++++++++++++--------
> >  tools/lib/perf/evsel.c                  |   9 +-
> >  tools/lib/perf/include/internal/evsel.h |   3 +-
> >  tools/perf/builtin-stat.c               |   9 +-
> >  tools/perf/tests/event_update.c         |   4 +-
> >  tools/perf/util/evlist.c                |  15 +--
> >  tools/perf/util/evsel.c                 |  55 +++++++++--
> >  tools/perf/util/evsel.h                 |   5 +
> >  tools/perf/util/expr.c                  |   2 +-
> >  tools/perf/util/header.c                |   4 +-
> >  tools/perf/util/parse-events.c          | 102 ++++++++++++++------
> >  tools/perf/util/pmus.c                  |  29 +++---
> >  tools/perf/util/pmus.h                  |   2 +
> >  tools/perf/util/stat.c                  |   6 +-
> >  tools/perf/util/synthetic-events.c      |   4 +-
> >  tools/perf/util/tool_pmu.c              |  56 +++++++++--
> >  tools/perf/util/tool_pmu.h              |   2 +-
> >  17 files changed, 297 insertions(+), 128 deletions(-)
> > 
> > --
> > 2.50.0.727.gbf7dc18ff4-goog
> >