Commit d38b223c authored by Mike Travis's avatar Mike Travis Committed by Ingo Molnar
Browse files

cpumask: reduce stack usage in find_lowest_rq 



Impact: reduce stack usage, cleanup

Use a cpumask_var_t in find_lowest_rq() and clean up other old
cpumask_t calls.

Signed-off-by: default avatarMike Travis <travis@sgi.com>
parent c90e785b

kernel/sched_rt.c

+22 −14
Original line number Diff line number Diff line
@@ -960,16 +960,17 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu) 


static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);



static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)

static inline int pick_optimal_cpu(int this_cpu,

				   const struct cpumask *mask)

{

	int first;



	/* "this_cpu" is cheaper to preempt than a remote processor */

	if ((this_cpu != -1) && cpu_isset(this_cpu, *mask))

	if ((this_cpu != -1) && cpumask_test_cpu(this_cpu, mask))

		return this_cpu;



	first = first_cpu(*mask);

	if (first != NR_CPUS)

	first = cpumask_first(mask);

	if (first < nr_cpu_ids)

		return first;



	return -1;
@@ -981,6 +982,7 @@ static int find_lowest_rq(struct task_struct *task) 
	struct cpumask *lowest_mask = __get_cpu_var(local_cpu_mask);

	int this_cpu = smp_processor_id();

	int cpu      = task_cpu(task);

	cpumask_var_t domain_mask;



	if (task->rt.nr_cpus_allowed == 1)

		return -1; /* No other targets possible */
@@ -1013,20 +1015,26 @@ static int find_lowest_rq(struct task_struct *task) 
	if (this_cpu == cpu)

		this_cpu = -1; /* Skip this_cpu opt if the same */



	if (alloc_cpumask_var(&domain_mask, GFP_ATOMIC)) {

		for_each_domain(cpu, sd) {

			if (sd->flags & SD_WAKE_AFFINE) {

			cpumask_t domain_mask;

				int best_cpu;



			cpumask_and(&domain_mask, sched_domain_span(sd),

				cpumask_and(domain_mask,

					    sched_domain_span(sd),

					    lowest_mask);



				best_cpu = pick_optimal_cpu(this_cpu,

						    &domain_mask);

			if (best_cpu != -1)

							    domain_mask);



				if (best_cpu != -1) {

					free_cpumask_var(domain_mask);

					return best_cpu;

				}

			}

		}

		free_cpumask_var(domain_mask);

	}



	/*

	 * And finally, if there were no matches within the domains