From: Peter Zijlstra <[email protected]> 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 <[email protected]> Tested-by: Philby John <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> LKML-Reference: <1281002322.1923.1708.ca...@laptop> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Paul Gortmaker <[email protected]> --- kernel/sched_fair.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 684e173..461d312 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -3588,6 +3588,8 @@ 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); -- 1.7.3.3 _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
