linux-kernel - Re: [PATCH V5 7/8] perf header: Support num and width of branch counters

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Date:   Wed, 25 Oct 2023 19:10:17 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     kan.liang@...ux.intel.com
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, adrian.hunter@...el.com, ak@...ux.intel.com,
        eranian@...gle.com, alexey.v.bayduraev@...ux.intel.com,
        tinghao.zhang@...el.com
Subject: Re: [PATCH V5 7/8] perf header: Support num and width of branch counters

On Wed, Oct 25, 2023 at 1:16 PM <kan.liang@...ux.intel.com> wrote:
>
> From: Kan Liang <kan.liang@...ux.intel.com>
>
> To support the branch counters feature, the information of the maximum
> number of supported counters and the width of the counters is exposed
> in the sysfs caps folder. The perf tool can use the information to parse
> the logged counters in each branch.
>
> Store the information in the perf_env for later usage.
>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>

Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

> ---
>
> No changes since V4
>
>  tools/perf/util/env.h    |  5 +++++
>  tools/perf/util/header.c | 18 +++++++++++++++---
>  2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
> index 4566c51f2fd9..48d7f8759a2a 100644
> --- a/tools/perf/util/env.h
> +++ b/tools/perf/util/env.h
> @@ -46,6 +46,9 @@ struct hybrid_node {
>  struct pmu_caps {
>         int             nr_caps;
>         unsigned int    max_branches;
> +       unsigned int    br_cntr_nr;
> +       unsigned int    br_cntr_width;
> +
>         char            **caps;
>         char            *pmu_name;
>  };
> @@ -62,6 +65,8 @@ struct perf_env {
>         unsigned long long      total_mem;
>         unsigned int            msr_pmu_type;
>         unsigned int            max_branches;
> +       unsigned int            br_cntr_nr;
> +       unsigned int            br_cntr_width;
>         int                     kernel_is_64_bit;
>
>         int                     nr_cmdline;
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index d812e1e371a7..9664062ba835 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -3256,7 +3256,9 @@ static int process_compressed(struct feat_fd *ff,
>  }
>
>  static int __process_pmu_caps(struct feat_fd *ff, int *nr_caps,
> -                             char ***caps, unsigned int *max_branches)
> +                             char ***caps, unsigned int *max_branches,
> +                             unsigned int *br_cntr_nr,
> +                             unsigned int *br_cntr_width)
>  {
>         char *name, *value, *ptr;
>         u32 nr_pmu_caps, i;
> @@ -3291,6 +3293,12 @@ static int __process_pmu_caps(struct feat_fd *ff, int *nr_caps,
>                 if (!strcmp(name, "branches"))
>                         *max_branches = atoi(value);
>
> +               if (!strcmp(name, "branch_counter_nr"))
> +                       *br_cntr_nr = atoi(value);
> +
> +               if (!strcmp(name, "branch_counter_width"))
> +                       *br_cntr_width = atoi(value);
> +
>                 free(value);
>                 free(name);
>         }
> @@ -3315,7 +3323,9 @@ static int process_cpu_pmu_caps(struct feat_fd *ff,
>  {
>         int ret = __process_pmu_caps(ff, &ff->ph->env.nr_cpu_pmu_caps,
>                                      &ff->ph->env.cpu_pmu_caps,
> -                                    &ff->ph->env.max_branches);
> +                                    &ff->ph->env.max_branches,
> +                                    &ff->ph->env.br_cntr_nr,
> +                                    &ff->ph->env.br_cntr_width);
>
>         if (!ret && !ff->ph->env.cpu_pmu_caps)
>                 pr_debug("cpu pmu capabilities not available\n");
> @@ -3344,7 +3354,9 @@ static int process_pmu_caps(struct feat_fd *ff, void *data __maybe_unused)
>         for (i = 0; i < nr_pmu; i++) {
>                 ret = __process_pmu_caps(ff, &pmu_caps[i].nr_caps,
>                                          &pmu_caps[i].caps,
> -                                        &pmu_caps[i].max_branches);
> +                                        &pmu_caps[i].max_branches,
> +                                        &pmu_caps[i].br_cntr_nr,
> +                                        &pmu_caps[i].br_cntr_width);
>                 if (ret)
>                         goto err;
>
> --
> 2.35.1
>