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sched: convert check_preempt_equal_prio to cpumask_var_t.

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Impact: stack reduction for large NR_CPUS

Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves
stack space.

We simply return if the allocation fails: since we don't use it we
could just pass NULL to cpupri_find and have it handle that.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Rusty Russell 2008-11-25 02:35:13 +10:30 committed by Ingo Molnar
parent 68e74568fb
commit 24600ce89a
1 changed files with 10 additions and 5 deletions
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15
kernel/sched_rt.c
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@ -805,17 +805,20 @@ static int select_task_rq_rt(struct task_struct *p, int sync)
static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
{
cpumask_t mask;
cpumask_var_t mask;
if (rq->curr->rt.nr_cpus_allowed == 1)
return;
if (p->rt.nr_cpus_allowed != 1
&& cpupri_find(&rq->rd->cpupri, p, &mask))
if (!alloc_cpumask_var(&mask, GFP_ATOMIC))
return;
if (!cpupri_find(&rq->rd->cpupri, rq->curr, &mask))
return;
if (p->rt.nr_cpus_allowed != 1
&& cpupri_find(&rq->rd->cpupri, p, mask))
goto free;
if (!cpupri_find(&rq->rd->cpupri, rq->curr, mask))
goto free;
/*
* There appears to be other cpus that can accept
@ -824,6 +827,8 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
*/
requeue_task_rt(rq, p, 1);
resched_task(rq->curr);
free:
free_cpumask_var(mask);
}
#endif /* CONFIG_SMP */