perf: Add a perf trace option to check samples ordering reliability

To ensure sample events time reordering is reliable, add a -d option
to perf trace to check that automatically.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 1d034f6fa28a..77f556f7604c 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -11,6 +11,8 @@
 
 static char const               *script_name;
 static char const               *generate_script_lang;
+static bool                     debug_ordering;
+static u64                      last_timestamp;
 
 static int default_start_script(const char *script __unused,
                                 int argc __unused,
@@ -87,6 +89,14 @@ static int process_sample_event(event_t *event, struct perf_session *session)
         }
 
         if (session->sample_type & PERF_SAMPLE_RAW) {
+                if (debug_ordering) {
+                        if (data.time < last_timestamp) {
+                                pr_err("Samples misordered, previous: %llu "
+                                        "this: %llu\n", last_timestamp,
+                                        data.time);
+                        }
+                        last_timestamp = data.time;
+                }
                 /*
                  * FIXME: better resolve from pid from the struct trace_entry
                  * field, although it should be the same than this perf
@@ -532,6 +542,8 @@ 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_END()
 };