On 09/08/07, Ingo Molnar <[email protected]> wrote:
>
> FYI, that's the patch i applied:
Thanks. Added my SOB below.
>
> --------------------------->
> Subject: sched: optimize task_tick_rt() a bit
> From: Dmitry Adamushko <[email protected]>
>
> Mitchell Erblich suggested a 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: [email protected] ]
>
> 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: Ingo Molnar <[email protected]>
Signed-off-by: Dmitry Adamushko <[email protected]>
> ---
> kernel/sched_rt.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> Index: linux/kernel/sched_rt.c
> ===================================================================
> --- linux.orig/kernel/sched_rt.c
> +++ linux/kernel/sched_rt.c
> @@ -207,10 +207,15 @@ static void task_tick_rt(struct rq *rq,
> return;
>
> p->time_slice = static_prio_timeslice(p->static_prio);
> - set_tsk_need_resched(p);
>
> - /* put it at the end of the queue: */
> - requeue_task_rt(rq, p);
> + /*
> + * 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 = {
>
--
Best regards,
Dmitry Adamushko
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