Re: [PATCH 13/15] perf stat: Fix JSON output in metric-only mode

[Ian Rogers]

On Wed, Nov 23, 2022 at 10:02 AM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> It generated a broken JSON output when aggregation mode or cgroup is
> used with --metric-only option.  Also get rid of the header line and
> make the output single line for each entry.
>
> It needs to know whether the current metric is the first one or not.
> So add 'first' field in the outstate and mark it false after printing.
>
> Before:
>   # perf stat -a -j --metric-only true
>   {"unit" : "GHz"}{"unit" : "insn per cycle"}{"unit" : "branch-misses of all branches"}
>   {{"metric-value" : "0.797"}{"metric-value" : "1.65"}{"metric-value" : "0.89"}
>    ^
>
>   # perf stat -a -j --metric-only --per-socket true
>   {"unit" : "GHz"}{"unit" : "insn per cycle"}{"unit" : "branch-misses of all branches"}
>   {"socket" : "S0", "aggregate-number" : 8, {"metric-value" : "0.295"}{"metric-value" : "1.88"}{"metric-value" : "0.64"}
>                                            ^
>
> After:
>   # perf stat -a -j --metric-only true
>   {"GHz" : "0.990", "insn per cycle" : "2.06", "branch-misses of all branches" : "0.59"}
>
>   # perf stat -a -j --metric-only --per-socket true
>   {"socket" : "S0", "aggregate-number" : 8, "GHz" : "0.439", "insn per cycle" : "2.14", "branch-misses of all branches" : "0.51"}
>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Acked-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/util/stat-display.c | 42 +++++++++++++++++++---------------
>  1 file changed, 24 insertions(+), 18 deletions(-)
>
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index 335627e8542d..43640115454c 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -279,9 +279,6 @@ static void print_aggr_id_json(struct perf_stat_config *config,
>  {
>         FILE *output = config->output;
>
> -       if (!config->interval)
> -               fputc('{', output);
> -
>         switch (config->aggr_mode) {
>         case AGGR_CORE:
>                 fprintf(output, "\"core\" : \"S%d-D%d-C%d\", \"aggregate-number\" : %d, ",
> @@ -335,6 +332,7 @@ static void aggr_printout(struct perf_stat_config *config,
>  struct outstate {
>         FILE *fh;
>         bool newline;
> +       bool first;
>         const char *prefix;
>         int  nfields;
>         int  nr;
> @@ -491,6 +489,7 @@ static void print_metric_only(struct perf_stat_config *config,
>
>         color_snprintf(str, sizeof(str), color ?: "", fmt, val);
>         fprintf(out, "%*s ", mlen, str);
> +       os->first = false;
>  }
>
>  static void print_metric_only_csv(struct perf_stat_config *config __maybe_unused,
> @@ -512,6 +511,7 @@ static void print_metric_only_csv(struct perf_stat_config *config __maybe_unused
>                 ends++;
>         *ends = 0;
>         fprintf(out, "%s%s", vals, config->csv_sep);
> +       os->first = false;
>  }
>
>  static void print_metric_only_json(struct perf_stat_config *config __maybe_unused,
> @@ -532,7 +532,8 @@ static void print_metric_only_json(struct perf_stat_config *config __maybe_unuse
>         while (isdigit(*ends) || *ends == '.')
>                 ends++;
>         *ends = 0;
> -       fprintf(out, "{\"metric-value\" : \"%s\"}", vals);
> +       fprintf(out, "%s\"%s\" : \"%s\"", os->first ? "" : ", ", unit, vals);
> +       os->first = false;
>  }
>
>  static void new_line_metric(struct perf_stat_config *config __maybe_unused,
> @@ -561,7 +562,7 @@ static void print_metric_header(struct perf_stat_config *config,
>         unit = fixunit(tbuf, os->evsel, unit);
>
>         if (config->json_output)
> -               fprintf(os->fh, "{\"unit\" : \"%s\"}", unit);
> +               return;
>         else if (config->csv_output)
>                 fprintf(os->fh, "%s%s", unit, config->csv_sep);
>         else
> @@ -821,6 +822,8 @@ static void print_counter_aggrdata(struct perf_stat_config *config,
>         run = aggr->counts.run;
>
>         if (!metric_only) {
> +               if (config->json_output)
> +                       fputc('{', output);
>                 if (os->prefix)
>                         fprintf(output, "%s", os->prefix);
>                 else if (config->summary && config->csv_output &&
> @@ -844,9 +847,12 @@ static void print_metric_begin(struct perf_stat_config *config,
>         struct aggr_cpu_id id;
>         struct evsel *evsel;
>
> +       os->first = true;
>         if (!config->metric_only)
>                 return;
>
> +       if (config->json_output)
> +               fputc('{', config->output);
>         if (os->prefix)
>                 fprintf(config->output, "%s", os->prefix);
>
> @@ -855,7 +861,7 @@ static void print_metric_begin(struct perf_stat_config *config,
>         aggr = &evsel->stats->aggr[aggr_idx];
>         aggr_printout(config, evsel, id, aggr->nr);
>
> -       print_cgroup(config, os->cgrp);
> +       print_cgroup(config, os->cgrp ? : evsel->cgrp);
>  }
>
>  static void print_metric_end(struct perf_stat_config *config)
> @@ -863,6 +869,8 @@ static void print_metric_end(struct perf_stat_config *config)
>         if (!config->metric_only)
>                 return;
>
> +       if (config->json_output)
> +               fputc('}', config->output);
>         fputc('\n', config->output);
>  }
>
> @@ -1005,11 +1013,9 @@ static void print_metric_headers_csv(struct perf_stat_config *config,
>                 fputs(aggr_header_csv[config->aggr_mode], config->output);
>  }
>
> -static void print_metric_headers_json(struct perf_stat_config *config,
> +static void print_metric_headers_json(struct perf_stat_config *config __maybe_unused,
>                                       bool no_indent __maybe_unused)
>  {
> -       if (config->interval)
> -               fputs("{\"unit\" : \"sec\"}", config->output);
>  }
>
>  static void print_metric_headers(struct perf_stat_config *config,
> @@ -1049,7 +1055,9 @@ static void print_metric_headers(struct perf_stat_config *config,
>                                               &config->metric_events,
>                                               &rt_stat);
>         }
> -       fputc('\n', config->output);
> +
> +       if (!config->json_output)
> +               fputc('\n', config->output);
>  }
>
>  static void prepare_interval(struct perf_stat_config *config,
> @@ -1058,17 +1066,14 @@ static void prepare_interval(struct perf_stat_config *config,
>         if (config->iostat_run)
>                 return;
>
> -       if (config->csv_output)
> +       if (config->json_output)
> +               scnprintf(prefix, len, "\"interval\" : %lu.%09lu, ",
> +                         (unsigned long) ts->tv_sec, ts->tv_nsec);
> +       else if (config->csv_output)
>                 scnprintf(prefix, len, "%lu.%09lu%s",
>                           (unsigned long) ts->tv_sec, ts->tv_nsec, config->csv_sep);
> -       else if (!config->json_output)
> -               scnprintf(prefix, len, "%6lu.%09lu ",
> -                         (unsigned long) ts->tv_sec, ts->tv_nsec);
> -       else if (!config->metric_only)
> -               scnprintf(prefix, len, "{\"interval\" : %lu.%09lu, ",
> -                         (unsigned long) ts->tv_sec, ts->tv_nsec);
>         else
> -               scnprintf(prefix, len, "{\"interval\" : %lu.%09lu}",
> +               scnprintf(prefix, len, "%6lu.%09lu ",
>                           (unsigned long) ts->tv_sec, ts->tv_nsec);
>  }
>
> @@ -1365,6 +1370,7 @@ void evlist__print_counters(struct evlist *evlist, struct perf_stat_config *conf
>         char buf[64];
>         struct outstate os = {
>                 .fh = config->output,
> +               .first = true,
>         };
>
>         if (config->iostat_run)
> --
> 2.38.1.584.g0f3c55d4c2-goog
>