perf stat: Fix --metric-only --json output

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: df936cadfb58ba93 ("perf stat: Add JSON output option")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Claire Jensen <cjense@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20221107213314.3239159-6-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 173f471..5c10cf4 100644 (file)
--- 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
@@ -845,10 +845,6 @@ 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);
@@ -869,18 +865,12 @@ 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);
 }
 
@@ -952,14 +942,8 @@ 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;
 }