linux-kernel - [PATCH 03/25] perf tools: Only override the default :tid comm entry

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Date:	Tue, 11 Nov 2014 16:16:41 +0200
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, 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>,
	Stephane Eranian <eranian@...gle.com>
Subject: [PATCH 03/25] perf tools: Only override the default :tid comm entry

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>
---
 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 a2157f0..9ebc8b1 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;
-- 
1.9.1

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