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Message-ID: <aM28tDp-BoNTVQwf@google.com>
Date: Fri, 19 Sep 2025 13:27:32 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Kan Liang <kan.liang@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: Re: [RFC/PATCH 2/2] perf check: Add 'pmu' subcommand
On Thu, Sep 18, 2025 at 08:33:30AM -0700, Ian Rogers wrote:
> On Wed, Sep 17, 2025 at 11:39 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > The 'perf check pmu' command will show information about PMUs in the
> > system like below:
> >
> > $ perf check pmu | head
> > cpu_atom: type = 10
> > core PMU: cpus = 16-27
> > caps: branches = 32
> > caps: max_precise = 3
> > caps: pmu_name = alderlake_hybrid
> > cpu_core: type = 4
> > core PMU: cpus = 0-15
> > caps: branches = 32
> > caps: max_precise = 3
> > caps: pmu_name = alderlake_hybrid
> >
> > The -q option will make it print the name and type of PMUs only. It
> > also takes arguments to show matching PMUs only.
> >
> > $ perf check pmu -q uncore
> > uncore_arb_0: type = 27
> > uncore_arb_1: type = 28
> > uncore_cbox_0: type = 15
> > uncore_cbox_1: type = 16
> > uncore_cbox_2: type = 17
> > uncore_cbox_3: type = 18
> > uncore_cbox_4: type = 19
> > uncore_cbox_5: type = 20
> > uncore_cbox_6: type = 21
> > uncore_cbox_7: type = 22
> > uncore_cbox_8: type = 23
> > uncore_cbox_9: type = 24
> > uncore_cbox_10: type = 25
> > uncore_cbox_11: type = 26
> > uncore_clock: type = 29
> > uncore_imc_free_running_0: type = 32
> > uncore_imc_free_running_1: type = 33
> > uncore_imc_0: type = 30
> > uncore_imc_1: type = 31
> >
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> > tools/perf/Documentation/perf-check.txt | 12 +++++
> > tools/perf/builtin-check.c | 60 ++++++++++++++++++++++++-
> > 2 files changed, 71 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/Documentation/perf-check.txt b/tools/perf/Documentation/perf-check.txt
> > index 34dccc29d90d2fdf..2fa007698c0f0814 100644
> > --- a/tools/perf/Documentation/perf-check.txt
> > +++ b/tools/perf/Documentation/perf-check.txt
> > @@ -11,6 +11,7 @@ SYNOPSIS
> > 'perf check' [<options>]
> > 'perf check' {feature <feature_list>} [<options>]
> > 'perf check' {system <setting_list>} [<options>]
> > +'perf check' {pmu <name_list>} [<options>]
> >
> > DESCRIPTION
> > -----------
> > @@ -26,6 +27,9 @@ is built-in, otherwise returns with exit status 1.
> > If the subcommand 'system' is used, then system settins are printed on
> > the standard output with explanation.
> >
> > +If the subcommand 'pmu' is used, then available PMU information is printed
> > +on the standard output with explanation.
> > +
> > SUBCOMMANDS
> > -----------
> >
> > @@ -88,6 +92,14 @@ SUBCOMMANDS
> > nmi_watchdog
> > kptr_restrict
> >
> > +pmu::
> > +
> > + Print PMU information available in the system.
> > +
> > + Example Usage:
> > + perf check pmu
> > + perf check pmu <name>
> > +
> >
> > OPTIONS
> > -------
> > diff --git a/tools/perf/builtin-check.c b/tools/perf/builtin-check.c
> > index 1c7c6bb5da5ccbf2..f3d034a94b1227c7 100644
> > --- a/tools/perf/builtin-check.c
> > +++ b/tools/perf/builtin-check.c
> > @@ -3,6 +3,8 @@
> > #include "color.h"
> > #include "util/debug.h"
> > #include "util/header.h"
> > +#include "util/pmu.h"
> > +#include "util/pmus.h"
> > #include <api/fs/fs.h>
> > #include <tools/config.h>
> > #include <stdbool.h>
> > @@ -10,13 +12,14 @@
> > #include <string.h>
> > #include <subcmd/parse-options.h>
> >
> > -static const char * const check_subcommands[] = { "feature", "system", NULL };
> > +static const char * const check_subcommands[] = { "feature", "system", "pmu", NULL };
> > static struct option check_options[] = {
> > OPT_BOOLEAN('q', "quiet", &quiet, "do not show any warnings or messages"),
> > OPT_END()
> > };
> > static struct option check_feature_options[] = { OPT_PARENT(check_options) };
> > static struct option check_system_options[] = { OPT_PARENT(check_options) };
> > +static struct option check_pmu_options[] = { OPT_PARENT(check_options) };
> >
> > static const char *check_usage[] = { NULL, NULL };
> > static const char *check_feature_usage[] = {
> > @@ -27,6 +30,10 @@ static const char *check_system_usage[] = {
> > "perf check system",
> > NULL
> > };
> > +static const char *check_pmu_usage[] = {
> > + "perf check pmu",
> > + NULL
> > +};
> >
> > #define FEATURE_STATUS(name_, macro_) { \
> > .name = name_, \
> > @@ -278,6 +285,55 @@ static int subcommand_system(int argc, const char **argv)
> > return 0;
> > }
> >
> > +/**
> > + * Usage: 'perf check pmu <names>'
> > + *
> > + * Show PMU information.
> > + */
> > +static int subcommand_pmu(int argc, const char **argv)
> > +{
> > + struct perf_pmu *pmu = NULL;
> > + struct perf_pmu_caps *caps;
> > +
> > + argc = parse_options(argc, argv, check_pmu_options, check_pmu_usage, 0);
> > +
> > + while ((pmu = perf_pmus__scan(pmu)) != NULL) {
> > + if (argc) {
> > + bool found = false;
> > +
> > + /* only show entries match to command line arguments */
> > + for (int k = 0; k < argc; k++) {
> > + if (strstr(pmu->name, argv[k])) {
>
> To avoid divergence from parse-events it may be better to use
> perf_pmu__wildcard_match? There is also
> perf_pmus__scan_matching_wildcard.
Sounds good, will change.
>
> > + found = true;
> > + break;
> > + }
> > + }
> > + if (!found)
> > + continue;
> > + }
> > +
> > + printf("%s: type = %u\n", pmu->name, pmu->type);
> > + if (quiet)
> > + continue;
> > +
> > + if (pmu->is_core || pmu->is_uncore) {
> > + printf(" %score PMU", pmu->is_uncore ? "un" : "");
> > + if (!perf_cpu_map__is_empty(pmu->cpus)) {
> > + printf(": %s = ", pmu->is_core ? "cpus" : "cpumask");
>
> The cpus file is only generally present on hybrid systems. I don't
> think this needs to be core/uncore dependent - the only thing I've
> ever seen fail that test are some ARM uncore PMUs. I'd always dump
> this as cpumask, when !core and !uncore then the default all online
> CPUs cpumask is important information as that probably isn't the
> cpumask you want with an uncore PMU.
Ok, I can remove the core/uncore check. But I think it's better to
print them only if they actually have maps to inform users that those
PMUs need some more care. :)
>
> > + cpu_map__fprintf(pmu->cpus, stdout);
> > + } else {
> > + printf("\n");
> > + }
> > + }
> > +
> > + perf_pmu__caps_parse(pmu);
> > + list_for_each_entry(caps, &pmu->caps, list) {
> > + printf(" caps: %s = %s\n", caps->name, caps->value);
> > + }
> > + }
> > + return 0;
>
> If not found return an error?
Yep, good idea.
Thanks for the review!
Namhyung
>
> > +}
> > +
> > int cmd_check(int argc, const char **argv)
> > {
> > argc = parse_options_subcommand(argc, argv, check_options,
> > @@ -290,6 +346,8 @@ int cmd_check(int argc, const char **argv)
> > return subcommand_feature(argc, argv);
> > if (strcmp(argv[0], "system") == 0)
> > return subcommand_system(argc, argv);
> > + if (strcmp(argv[0], "pmu") == 0)
> > + return subcommand_pmu(argc, argv);
> >
> > /* If no subcommand matched above, print usage help */
> > pr_err("Unknown subcommand: %s\n", argv[0]);
> > --
> > 2.51.0
> >
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