linux-kernel - Re: [PATCH 03/11] perf stat: Fix --metric-only --json output

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Date:   Mon, 14 Nov 2022 10:18:30 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        James Clark <james.clark@....com>
Subject: Re: [PATCH 03/11] perf stat: Fix --metric-only --json output

On Fri, Nov 11, 2022 at 7:22 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> Currently it prints all metric headers for JSON output.  But actually it
> skips some metrics with valid_only_metric().  So the output looks like:
>
>   $ perf stat --metric-only --json true
>   {"unit" : "CPUs utilized", "unit" : "/sec", "unit" : "/sec", "unit" : "/sec", "unit" : "GHz", "unit" : "insn per cycle", "unit" : "/sec", "unit" : "branch-misses of all branches"}
>   {"metric-value" : "3.861"}{"metric-value" : "0.79"}{"metric-value" : "3.04"}
>
> As you can see there are 8 units in the header but only 3 metric-values
> are there.  It should skip the unused headers as well.  Also each unit
> should be printed as a separate object like metric values.
>
> With this patch:
>
>   $ perf stat --metric-only --json true
>   {"unit" : "GHz"}{"unit" : "insn per cycle"}{"unit" : "branch-misses of all branches"}
>   {"metric-value" : "4.166"}{"metric-value" : "0.73"}{"metric-value" : "2.96"}
>
> Fixes: df936cadfb58 ("perf stat: Add JSON output option")
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>

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

Thanks,
Ian

> ---
>  tools/perf/util/stat-display.c | 22 +++-------------------
>  1 file changed, 3 insertions(+), 19 deletions(-)
>
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index c7b3a1e10263..96ad0c71adc2 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -430,12 +430,12 @@ static void print_metric_header(struct perf_stat_config *config,
>             os->evsel->priv != os->evsel->evlist->selected->priv)
>                 return;
>
> -       if (!valid_only_metric(unit) && !config->json_output)
> +       if (!valid_only_metric(unit))
>                 return;
>         unit = fixunit(tbuf, os->evsel, unit);
>
>         if (config->json_output)
> -               fprintf(os->fh, "\"unit\" : \"%s\"", unit);
> +               fprintf(os->fh, "{\"unit\" : \"%s\"}", unit);
>         else if (config->csv_output)
>                 fprintf(os->fh, "%s%s", unit, config->csv_sep);
>         else
> @@ -847,10 +847,6 @@ static void print_metric_headers(struct perf_stat_config *config,
>                 .new_line = new_line_metric,
>                 .force_header = true,
>         };
> -       bool first = true;
> -
> -       if (config->json_output && !config->interval)
> -               fprintf(config->output, "{");
>
>         if (prefix && !config->json_output)
>                 fprintf(config->output, "%s", prefix);
> @@ -871,18 +867,12 @@ static void print_metric_headers(struct perf_stat_config *config,
>         evlist__for_each_entry(evlist, counter) {
>                 os.evsel = counter;
>
> -               if (!first && config->json_output)
> -                       fprintf(config->output, ", ");
> -               first = false;
> -
>                 perf_stat__print_shadow_stats(config, counter, 0,
>                                               0,
>                                               &out,
>                                               &config->metric_events,
>                                               &rt_stat);
>         }
> -       if (config->json_output)
> -               fprintf(config->output, "}");
>         fputc('\n', config->output);
>  }
>
> @@ -954,14 +944,8 @@ static void print_interval(struct perf_stat_config *config,
>                 }
>         }
>
> -       if ((num_print_interval == 0 || config->interval_clear)
> -                        && metric_only && !config->json_output)
> +       if ((num_print_interval == 0 || config->interval_clear) && metric_only)
>                 print_metric_headers(config, evlist, " ", true);
> -       if ((num_print_interval == 0 || config->interval_clear)
> -                        && metric_only && config->json_output) {
> -               fprintf(output, "{");
> -               print_metric_headers(config, evlist, " ", true);
> -       }
>         if (++num_print_interval == 25)
>                 num_print_interval = 0;
>  }
> --
> 2.38.1.493.g58b659f92b-goog
>