Commit 861d034e authored Aug 19, 2010 by Peter Zijlstra Committed by Ingo Molnar Aug 20, 2010

sched: Fix rq->clock synchronization when migrating tasks



sched_fork() -- we do task placement in ->task_fork_fair() ensure we
  update_rq_clock() so we work with current time. We leave the vruntime
  in relative state, so the time delay until wake_up_new_task() doesn't
  matter.

wake_up_new_task() -- Since task_fork_fair() left p->vruntime in
  relative state we can safely migrate, the activate_task() on the
  remote rq will call update_rq_clock() and causes the clock to be
  synced (enough).

Tested-by: Jack Daniel <wanders.thirst@gmail.com>
Tested-by: Philby John <pjohn@mvista.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1281002322.1923.1708.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 763008c4

kernel/sched_fair.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -3752,6 +3752,8 @@ static void task_fork_fair(struct task_struct *p)

		raw_spin_lock_irqsave(&rq->lock, flags);

		update_rq_clock(rq);

		if (unlikely(task_cpu(p) != this_cpu))
		__set_task_cpu(p, this_cpu);

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