On Fri, Oct 19, 2007 at 02:42:56PM -0400, Steven Rostedt wrote:
> This patch adds accounting to each runqueue to keep track of the
> highest prio task queued on the run queue. We only care about
> RT tasks, so if the run queue does not contain any active RT tasks
> its priority will be considered MAX_RT_PRIO.
>
> This information will be used for later patches.
>
[...]
> @@ -972,6 +974,8 @@ static void activate_task(struct rq *rq,
>
> enqueue_task(rq, p, wakeup);
> inc_nr_running(p, rq);
> +
> + rq_prio_add_task(rq, p);
> }
>
> /*
> @@ -984,6 +988,8 @@ static void deactivate_task(struct rq *r
>
> dequeue_task(rq, p, sleep);
> dec_nr_running(p, rq);
> +
> + rq_prio_remove_task(rq, p);
> }
>
> /**
> @@ -6619,6 +6625,7 @@ void __init sched_init(void)
> rq->cpu = i;
> rq->migration_thread = NULL;
> INIT_LIST_HEAD(&rq->migration_queue);
> + rq->highest_prio = MAX_RT_PRIO;
> #endif
> atomic_set(&rq->nr_iowait, 0);
>
> Index: linux-test.git/kernel/sched_rt.c
> ===================================================================
> --- linux-test.git.orig/kernel/sched_rt.c 2007-10-19 12:33:09.000000000 -0400
> +++ linux-test.git/kernel/sched_rt.c 2007-10-19 12:33:23.000000000 -0400
> @@ -110,6 +110,31 @@ static struct task_struct *pick_next_tas
> return next;
> }
>
> +#ifdef CONFIG_SMP
> +static inline void rq_prio_add_task(struct rq *rq, struct task_struct *p)
> +{
> + if (unlikely(rt_task(p)) && p->prio < rq->highest_prio)
> + rq->highest_prio = p->prio;
> +}
> +
> +static inline void rq_prio_remove_task(struct rq *rq, struct task_struct *p)
> +{
> + struct rt_prio_array *array;
> +
> + if (unlikely(rt_task(p))) {
> + if (rq->rt_nr_running) {
> + if (p->prio >= rq->highest_prio) {
> + /* recalculate */
> + array = &rq->rt.active;
> + rq->highest_prio =
> + sched_find_first_bit(array->bitmap);
> + } /* otherwise leave rq->highest prio alone */
> + } else
> + rq->highest_prio = MAX_RT_PRIO;
> + }
> +}
> +#endif /* CONFIG_SMP */
> +
Sorry, I forgot to test this on UP. Seems to be missing a
#define rq_prio_remove_task(rq, p) do { } while(0)
#define rq_prio_add(rq, p) do { } while(0)
for the !CONFIG_SMP case.
Will fix.
-- Steve
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