[tip:sched/core] sched: Update rq clock before migrating tasks out of dying CPU

[tip-bot for Frederic Weisbecker <tipbot@zytor.com>]

Commit-ID:  77bd39702f0b3840cea17681409270b16a3b93c0
Gitweb:     http://git.kernel.org/tip/77bd39702f0b3840cea17681409270b16a3b93c0
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Fri, 12 Apr 2013 01:50:58 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 May 2013 09:40:23 +0200

sched: Update rq clock before migrating tasks out of dying CPU

Because the sched_class::put_prev_task() callback of rt and fair
classes are referring to the rq clock to update their runtime
statistics. There is a missing rq clock update from the CPU
hotplug notifier's entry point of the scheduler.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 79e48e6..7bf0418 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4378,6 +4378,13 @@ static void migrate_tasks(unsigned int dead_cpu)
 	 */
 	rq->stop = NULL;
 
+	/*
+	 * put_prev_task() and pick_next_task() sched
+	 * class method both need to have an up-to-date
+	 * value of rq->clock[_task]
+	 */
+	update_rq_clock(rq);
+
 	for ( ; ; ) {
 		/*
 		 * There's this thread running, bail when that's the only