perf hist: Clarify events_stats fields usage

The events_stats.total field is too generic, rename it to .total_period,
and also add a comment explaining that it is the sum of all the .period
fields in samples, that is needed because we use auto-freq to avoid
sampling artifacts.

Ditto for events_stats.lost, that is the sum of all lost_event.lost
fields, i.e. the number of events the kernel dropped.

Looking at the users, builtin-sched.c can make use of these fields and
stop doing it again.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 11 deletions

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index aef6ed0e119c..be7bc9264710 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1641,19 +1641,10 @@ static int process_sample_event(event_t *event, struct perf_session *session)
 	return 0;
 }
 
-static int process_lost_event(event_t *event __used,
-			      struct perf_session *session __used)
-{
-	nr_lost_chunks++;
-	nr_lost_events += event->lost.lost;
-
-	return 0;
-}
-
 static struct perf_event_ops event_ops = {
 	.sample			= process_sample_event,
 	.comm			= event__process_comm,
-	.lost			= process_lost_event,
+	.lost			= event__process_lost,
 	.ordered_samples	= true,
 };
 
@@ -1664,8 +1655,12 @@ static int read_events(void)
 	if (session == NULL)
 		return -ENOMEM;
 
-	if (perf_session__has_traces(session, "record -R"))
+	if (perf_session__has_traces(session, "record -R")) {
 		err = perf_session__process_events(session, &event_ops);
+		nr_events      = session->hists.stats.nr_events[0];
+		nr_lost_events = session->hists.stats.total_lost;
+		nr_lost_chunks = session->hists.stats.nr_events[PERF_RECORD_LOST];
+	}
 
 	perf_session__delete(session);
 	return err;