perf hist: Add nr_lost_samples to hist_stats

This is a preparation to display accurate lost sample counts for
each evsel.

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220901195739.668604-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/events_stats.h

@@ -47,6 +47,7 @@ struct hists_stats {
 	u64 total_non_filtered_period;
 	u32 nr_samples;
 	u32 nr_non_filtered_samples;
+	u32 nr_lost_samples;
 };
 
 void events_stats__inc(struct events_stats *stats, u32 type);

tools/perf/util/hist.c

@@ -2335,6 +2335,11 @@ void hists__inc_nr_samples(struct hists *hists, bool filtered)
 		hists->stats.nr_non_filtered_samples++;
 }
 
+void hists__inc_nr_lost_samples(struct hists *hists, u32 lost)
+{
+	hists->stats.nr_lost_samples += lost;
+}
+
 static struct hist_entry *hists__add_dummy_entry(struct hists *hists,
 						 struct hist_entry *pair)
 {

tools/perf/util/hist.h

@@ -201,6 +201,7 @@ void hists__reset_stats(struct hists *hists);
 void hists__inc_stats(struct hists *hists, struct hist_entry *h);
 void hists__inc_nr_events(struct hists *hists);
 void hists__inc_nr_samples(struct hists *hists, bool filtered);
+void hists__inc_nr_lost_samples(struct hists *hists, u32 lost);
 
 size_t hists__fprintf(struct hists *hists, bool show_header, int max_rows,
 		      int max_cols, float min_pcnt, FILE *fp,