Commit 98fbc798 authored Aug 24, 2007 by Dmitry Adamushko Committed by Ingo Molnar Aug 24, 2007

sched: optimize task_tick_rt() a bit



Mitchell Erblich suggested a quality-of-implementation change to
not requeue SCHED_RR tasks if there's only a single task on the
runqueue, by checking for rq->nr_running == 1.

provide a more efficient implementation of that, to check that
particular RT priority-queue only.

[ From: mingo@elte.hu ]

Also first requeue the task then set need_resched - results in slightly
better machine-instruction ordering. Also clean up the code a bit.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent deac4ee6

kernel/sched_rt.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -207,10 +207,15 @@ static void task_tick_rt(struct rq rq, struct task_struct p)
		return;

		p->time_slice = static_prio_timeslice(p->static_prio);
		set_tsk_need_resched(p);

		/* put it at the end of the queue: */
		/*
		* Requeue to the end of queue if we are not the only element
		* on the queue:
		*/
		if (p->run_list.prev != p->run_list.next) {
		requeue_task_rt(rq, p);
		set_tsk_need_resched(p);
		}
		}

		static struct sched_class rt_sched_class __read_mostly = {