sched: convert check_preempt_equal_prio to cpumask_var_t. (24600ce8) · Commits · 戴 / test

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>

kernel/sched_rt.c

+10 −5

Original line number	Diff line number	Diff line
		@@ -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 */

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