linux-kernel - [PATCH 03/10] perf sched timehist: Handle zero sample->tid properly

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Date:   Tue,  6 Dec 2016 12:40:03 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <andi@...stfloor.org>,
        Minchan Kim <minchan@...nel.org>
Subject: [PATCH 03/10] perf sched timehist: Handle zero sample->tid properly

Sometimes samples have tid of 0 but non-0 pid.  It ends up having a
new thread of 0 tid/pid (instead of referring idle task) since tid is
used to search matching task.  But I guess it's wrong to use 0 as a
tid when pid is set.  This patch uses tid only if it has a non-zero
value or same as pid (of 0).

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/builtin-sched.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 6991686bcaa5..e34a71166b4a 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2118,7 +2118,9 @@ static struct thread *timehist_get_thread(struct perf_sched *sched,
 			pr_err("Failed to get idle thread for cpu %d.\n", sample->cpu);
 
 	} else {
-		thread = machine__findnew_thread(machine, sample->pid, sample->tid);
+		/* there were samples with tid 0 but non-zero pid */
+		thread = machine__findnew_thread(machine, sample->pid,
+						 sample->tid ?: sample->pid);
 		if (thread == NULL) {
 			pr_debug("Failed to get thread for tid %d. skipping sample.\n",
 				 sample->tid);
-- 
2.10.1