linux-kernel - [PATCH 16/16] perf tools: Only override the default :tid comm entry

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Date:	Wed, 19 Nov 2014 13:03:36 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 16/16] perf tools: Only override the default :tid comm entry

From: Adrian Hunter <adrian.hunter@...el.com>

Events may still be ordered even if there are no timestamps e.g. if the
data is recorded per-thread.

Also synthesized COMM events have a timestamp of zero.

Consequently it is better to keep comm entries even if they have a
timestamp of zero.

However, when a struct thread is created the command string is not known
and a comm entry with a string of the form ":<tid>" is used.

In that case thread->comm_set is false and the comm entry should be
overridden.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...il.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lkml.kernel.org/r/1415715423-15563-4-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/thread.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index a2157f0ef1df..9ebc8b1f9be5 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -103,15 +103,14 @@ struct comm *thread__exec_comm(const struct thread *thread)
 	return last;
 }
 
-/* CHECKME: time should always be 0 if event aren't ordered */
 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 		       bool exec)
 {
 	struct comm *new, *curr = thread__comm(thread);
 	int err;
 
-	/* Override latest entry if it had no specific time coverage */
-	if (!curr->start && !curr->exec) {
+	/* Override the default :tid entry */
+	if (!thread->comm_set) {
 		err = comm__override(curr, str, timestamp, exec);
 		if (err)
 			return err;
-- 
1.9.3

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