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>

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 1d034f6fa28a6fafc151468be80cfa8178105f01..77f556f7604c0f5f9db54042d1c311f5d04e3884 100644 (file)
--- 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()
 };