sched: optimize schedule() a bit on SMP



optimize schedule() a bit on SMP, by moving the rq-clock update
outside the rq lock.

code size is the same:

      text    data     bss     dec     hex filename
     25725    2666      96   28487    6f47 sched.o.before
     25725    2666      96   28487    6f47 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

parent 08ec3df5

kernel/sched.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -3481,9 +3481,13 @@ need_resched_nonpreemptible:

		schedule_debug(prev);

		spin_lock_irq(&rq->lock);
		clear_tsk_need_resched(prev);
		/*
		* Do the rq-clock update outside the rq lock:
		*/
		local_irq_disable();
		__update_rq_clock(rq);
		spin_lock(&rq->lock);
		clear_tsk_need_resched(prev);

		if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
		if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&