perf: Report lost events in perf trace debug mode

Account and report lost events in perf trace debugging mode,
useful to check the reliability of the traces.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Tom Zanussi <tzanussi@gmail.com>

1 files changed, 17 insertions, 5 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 83df8db4f358..294da725a57d 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -11,7 +11,7 @@
 
 static char const               *script_name;
 static char const               *generate_script_lang;
-static bool                     debug_ordering;
+static bool                     debug_mode;
 static u64                      last_timestamp;
 static u64                      nr_unordered;
 
@@ -92,7 +92,7 @@ static int process_sample_event(event_t *event, struct perf_session *session)
         }
 
         if (session->sample_type & PERF_SAMPLE_RAW) {
-                if (debug_ordering) {
+                if (debug_mode) {
                         if (data.time < last_timestamp) {
                                 pr_err("Samples misordered, previous: %llu "
                                         "this: %llu\n", last_timestamp,
@@ -116,6 +116,15 @@ static int process_sample_event(event_t *event, struct perf_session *session)
         return 0;
 }
 
+static u64 nr_lost;
+
+static int process_lost_event(event_t *event, struct perf_session *session __used)
+{
+        nr_lost += event->lost.lost;
+
+        return 0;
+}
+
 static struct perf_event_ops event_ops = {
         .sample = process_sample_event,
         .comm   = event__process_comm,
@@ -123,6 +132,7 @@ static struct perf_event_ops event_ops = {
         .event_type = event__process_event_type,
         .tracing_data = event__process_tracing_data,
         .build_id = event__process_build_id,
+        .lost = process_lost_event,
         .ordered_samples = true,
 };
 
@@ -141,8 +151,10 @@ static int __cmd_trace(struct perf_session *session)
 
         ret = perf_session__process_events(session, &event_ops);
 
-        if (debug_ordering)
+        if (debug_mode) {
                 pr_err("Misordered timestamps: %llu\n", nr_unordered);
+                pr_err("Lost events: %llu\n", nr_lost);
+        }
 
         return ret;
 }
@@ -554,8 +566,8 @@ static const struct option options[] = {
                    "generate perf-trace.xx script in specified language"),
         OPT_STRING('i', "input", &input_name, "file",
                     "input file name"),
-        OPT_BOOLEAN('d', "debug-ordering", &debug_ordering,
-                   "check that samples time ordering is monotonic"),
+        OPT_BOOLEAN('d', "debug-mode", &debug_mode,
+                   "do various checks like samples ordering and lost events"),
 
         OPT_END()
 };