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, 12 insertions, 4 deletions

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index be56f3efa413..4910194acaa6 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -85,6 +85,7 @@ struct report {
 	bool			group_set;
 	bool			stitch_lbr;
 	bool			disable_order;
+	bool			skip_empty;
 	int			max_stack;
 	struct perf_read_values	show_threads_values;
 	struct annotation_options annotation_opts;
@@ -530,6 +531,9 @@ static int evlist__tty_browse_hists(struct evlist *evlist, struct report *rep, c
 		if (symbol_conf.event_group && !evsel__is_group_leader(pos))
 			continue;
 
+		if (rep->skip_empty && !hists->stats.nr_samples)
+			continue;
+
 		hists__fprintf_nr_sample_events(hists, rep, evname, stdout);
 
 		if (rep->total_cycles_mode) {
@@ -731,8 +735,8 @@ static int stats_print(struct report *rep)
 {
 	struct perf_session *session = rep->session;
 
-	perf_session__fprintf_nr_events(session, stdout);
-	perf_evlist__fprintf_nr_events(session->evlist, stdout);
+	perf_session__fprintf_nr_events(session, stdout, rep->skip_empty);
+	evlist__fprintf_nr_events(session->evlist, stdout, rep->skip_empty);
 	return 0;
 }
 
@@ -944,8 +948,10 @@ static int __cmd_report(struct report *rep)
 			perf_session__fprintf_dsos(session, stdout);
 
 		if (dump_trace) {
-			perf_session__fprintf_nr_events(session, stdout);
-			evlist__fprintf_nr_events(session->evlist, stdout);
+			perf_session__fprintf_nr_events(session, stdout,
+							rep->skip_empty);
+			evlist__fprintf_nr_events(session->evlist, stdout,
+						  rep->skip_empty);
 			return 0;
 		}
 	}
@@ -1313,6 +1319,8 @@ int cmd_report(int argc, const char **argv)
 		    "Sort all blocks by 'Sampled Cycles%'"),
 	OPT_BOOLEAN(0, "disable-order", &report.disable_order,
 		    "Disable raw trace ordering"),
+	OPT_BOOLEAN(0, "skip-empty", &report.skip_empty,
+		    "Do not display empty (or dummy) events in the output"),
 	OPT_END()
 	};
 	struct perf_data data = {