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SubjectRe: [patch] sched-2.5.64-D3, more interactivity changes
Well, I don't have an interactivity test ... but ran the kerbench and
SDET standard batch job stuff on the big NUMA-Q box, and it's the same ...
incidentally ... I tested the earlier changes individually, and they
actually made things slightly *faster*. Is cool to see that we're improving
both worlds at once.

M.

--On Monday, March 17, 2003 11:21:33 +0100 Ingo Molnar <mingo@elte.hu> wrote:

>
> the attached patch (against BK-curr) implements more finegrained timeslice
> distribution, without changing the total balance of timeslices, by
> recalculating the priority of CPU-bound tasks at a finer granularity, and
> by roundrobining tasks. Right now this new granularity is 50 msecs (the
> default timeslice for default priority tasks is 100 msecs).
>
> Could people, who can reproduce 'audio skips' kind of problems even with
> BK-curr, give this patch a go?
>
> Ingo
>
> --- linux/kernel/sched.c.orig
> +++ linux/kernel/sched.c
> @@ -73,6 +73,7 @@
> #define INTERACTIVE_DELTA 2
> #define MAX_SLEEP_AVG (10*HZ)
> #define STARVATION_LIMIT (10*HZ)
> +#define TIMESLICE_GRANULARITY (HZ/20 ?: 1)
> #define NODE_THRESHOLD 125
>
> /*
> @@ -1259,6 +1260,27 @@ void scheduler_tick(int user_ticks, int
> enqueue_task(p, rq->expired);
> } else
> enqueue_task(p, rq->active);
> + } else {
> + /*
> + * Prevent a too long timeslice allowing a task to monopolize
> + * the CPU. We do this by splitting up the timeslice into
> + * smaller pieces.
> + *
> + * Note: this does not mean the task's timeslices expire or
> + * get lost in any way, they just might be preempted by
> + * another task of equal priority. (one with higher
> + * priority would have preempted this task already.) We
> + * requeue this task to the end of the list on this priority
> + * level, which is in essence a round-robin of tasks with
> + * equal priority.
> + */
> + if (!(p->time_slice % TIMESLICE_GRANULARITY) &&
> + (p->array == rq->active)) {
> + dequeue_task(p, rq->active);
> + set_tsk_need_resched(p);
> + p->prio = effective_prio(p);
> + enqueue_task(p, rq->active);
> + }
> }
> out:
> spin_unlock(&rq->lock);
>
> -
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