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Message-ID: <CAP-5=fVt4Nu3ZtKD+DWn9iT1XRzbbzvE3WXaO51V+8UGCE56cg@mail.gmail.com>
Date: Wed, 16 Jul 2025 13:25:17 -0700
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Thomas Falcon <thomas.falcon@...el.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>,
Adrian Hunter <adrian.hunter@...el.com>, Kan Liang <kan.liang@...ux.intel.com>,
Ben Gainey <ben.gainey@....com>, James Clark <james.clark@...aro.org>,
Howard Chu <howardchu95@...il.com>, Weilin Wang <weilin.wang@...el.com>,
Levi Yun <yeoreum.yun@....com>, "Dr. David Alan Gilbert" <linux@...blig.org>,
Zhongqiu Han <quic_zhonhan@...cinc.com>, Blake Jones <blakejones@...gle.com>,
Yicong Yang <yangyicong@...ilicon.com>, Anubhav Shelat <ashelat@...hat.com>,
Thomas Richter <tmricht@...ux.ibm.com>,
Jean-Philippe Romain <jean-philippe.romain@...s.st.com>, Song Liu <song@...nel.org>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 04/12] perf parse-events: Allow the cpu term to be a PMU
On Wed, Jul 16, 2025 at 1:09 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Fri, Jun 27, 2025 at 12:24:09PM -0700, Ian Rogers wrote:
> > On hybrid systems, events like msr/tsc/ will aggregate counts across
> > all CPUs. Often metrics only want a value like msr/tsc/ for the cores
> > on which the metric is being computed. Listing each CPU with terms
> > cpu=0,cpu=1.. is laborious and would need to be encoded for all
> > variations of a CPU model.
> >
> > Allow the cpumask from a PMU to be an argument to the cpu term. For
> > example in the following the cpumask of the cstate_pkg PMU selects the
> > CPUs to count msr/tsc/ counter upon:
> > ```
> > $ cat /sys/bus/event_source/devices/cstate_pkg/cpumask
> > 0
> > $ perf stat -A -e 'msr/tsc,cpu=cstate_pkg/' -a sleep 0.1
>
> It can be confusing if 'cpu' takes a number or a PMU name. What about
> adding a new term (maybe 'cpu_from') to handle this case?
So it is possible for terms to be defined in sysfs in the 'format/' folder:
```
$ ls /sys/bus/event_source/devices/cpu_core/format/
cmask edge event frontend inv ldlat offcore_rsp pc umask
```
By not introducing a new term we leave 'cpu_from' open for use in this
way. When I spoke to Kan we thought using the existing term made sense
and fits the idea of leaving things open for the kernel/drivers to
use. It is possible to add a new term though. Let me know and I can
update the patch and documentation accordingly.
Thanks,
Ian
> Also please update the documentation.
>
> Thanks,
> Namhyung
>
> >
> > Performance counter stats for 'system wide':
> >
> > CPU0 252,621,253 msr/tsc,cpu=cstate_pkg/
> >
> > 0.101184092 seconds time elapsed
> > ```
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> > tools/perf/util/parse-events.c | 37 +++++++++++++++++++++++++---------
> > 1 file changed, 28 insertions(+), 9 deletions(-)
> >
> > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> > index 7a32d5234a64..ef38eb082342 100644
> > --- a/tools/perf/util/parse-events.c
> > +++ b/tools/perf/util/parse-events.c
> > @@ -192,10 +192,20 @@ static struct perf_cpu_map *get_config_cpu(const struct parse_events_terms *head
> >
> > list_for_each_entry(term, &head_terms->terms, list) {
> > if (term->type_term == PARSE_EVENTS__TERM_TYPE_CPU) {
> > - struct perf_cpu_map *cpu = perf_cpu_map__new_int(term->val.num);
> > + struct perf_cpu_map *term_cpus;
> >
> > - perf_cpu_map__merge(&cpus, cpu);
> > - perf_cpu_map__put(cpu);
> > + if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM) {
> > + term_cpus = perf_cpu_map__new_int(term->val.num);
> > + } else {
> > + struct perf_pmu *pmu = perf_pmus__find(term->val.str);
> > +
> > + if (perf_cpu_map__is_empty(pmu->cpus))
> > + term_cpus = pmu->is_core ? cpu_map__online() : NULL;
> > + else
> > + term_cpus = perf_cpu_map__get(pmu->cpus);
> > + }
> > + perf_cpu_map__merge(&cpus, term_cpus);
> > + perf_cpu_map__put(term_cpus);
> > }
> > }
> >
> > @@ -1054,12 +1064,21 @@ do { \
> > }
> > break;
> > case PARSE_EVENTS__TERM_TYPE_CPU:
> > - CHECK_TYPE_VAL(NUM);
> > - if (term->val.num >= (u64)cpu__max_present_cpu().cpu) {
> > - parse_events_error__handle(err, term->err_val,
> > - strdup("too big"),
> > - NULL);
> > - return -EINVAL;
> > + if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM) {
> > + if (term->val.num >= (u64)cpu__max_present_cpu().cpu) {
> > + parse_events_error__handle(err, term->err_val,
> > + strdup("too big"),
> > + /*help=*/NULL);
> > + return -EINVAL;
> > + }
> > + } else {
> > + assert(term->type_val == PARSE_EVENTS__TERM_TYPE_STR);
> > + if (perf_pmus__find(term->val.str) == NULL) {
> > + parse_events_error__handle(err, term->err_val,
> > + strdup("not a valid PMU"),
> > + /*help=*/NULL);
> > + return -EINVAL;
> > + }
> > }
> > break;
> > case PARSE_EVENTS__TERM_TYPE_DRV_CFG:
> > --
> > 2.50.0.727.gbf7dc18ff4-goog
> >
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