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>

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 83df8db4f3588a78cea6448b5edab9d0872ac60f..294da725a57d12867788baa9c5ea98c410486cdf 100644 (file)
--- 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()
 };