| | Date | Sat, 18 Sep 2010 11:59:06 -0700 | | From | Greg KH <> | | Subject | [102/123] sched: Fix rq->clock synchronization when migrating tasks |
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From: Peter Zijlstra <peterz@infradead.org>
commit 861d034ee814917a83bd5de4b26e3b8336ddeeb8 upstream
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> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- kernel/sched_fair.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1963,6 +1963,8 @@ static void task_fork_fair(struct task_s 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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