perf report: Add --skip-empty option to suppress 0 event stat

To make the output more readable, I think it's better to remove 0's in
the output.  Also the dummy event has no event stats so it just wasts
the space.  Let's use the --skip-empty option to suppress it.

  $ perf report --stat --skip-empty

  Aggregated stats:
             TOTAL events:      16530
              MMAP events:        226
              COMM events:       1596
              EXIT events:          2
          THROTTLE events:        121
        UNTHROTTLE events:        117
              FORK events:       1595
            SAMPLE events:        719
             MMAP2 events:      12147
            CGROUP events:          2
    FINISHED_ROUND events:          2
        THREAD_MAP events:          1
           CPU_MAP events:          1
         TIME_CONV events:          1
  cycles stats:
            SAMPLE events:        719

Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427013717.1651674-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index eba3769be3f1..a6659b616e6d 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -2352,7 +2352,8 @@ size_t perf_session__fprintf_dsos_buildid(struct perf_session *session, FILE *fp
 	return machines__fprintf_dsos_buildid(&session->machines, fp, skip, parm);
 }
 
-size_t perf_session__fprintf_nr_events(struct perf_session *session, FILE *fp)
+size_t perf_session__fprintf_nr_events(struct perf_session *session, FILE *fp,
+				       bool skip_empty)
 {
 	size_t ret;
 	const char *msg = "";
@@ -2362,7 +2363,7 @@ size_t perf_session__fprintf_nr_events(struct perf_session *session, FILE *fp)
 
 	ret = fprintf(fp, "\nAggregated stats:%s\n", msg);
 
-	ret += events_stats__fprintf(&session->evlist->stats, fp);
+	ret += events_stats__fprintf(&session->evlist->stats, fp, skip_empty);
 	return ret;
 }