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Commit e2c88063 authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar
Browse files

cpumask: Simplify sched_rt.c 



find_lowest_rq() wants to call pick_optimal_cpu() on the
intersection of sched_domain_span(sd) and lowest_mask.  Rather
than doing a cpus_and into a temporary, we can open-code it.

This actually makes the code slightly clearer, IMHO.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarGregory Haskins <ghaskins@novell.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <200911031453.15350.rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 45a5c8ba

kernel/sched_rt.c

+24 −37
Original line number Diff line number Diff line
@@ -1153,29 +1153,12 @@ 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,

				   const struct cpumask *mask)

{

	int first;



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

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

		return this_cpu;



	first = cpumask_first(mask);

	if (first < nr_cpu_ids)

		return first;



	return -1;

}



static int find_lowest_rq(struct task_struct *task)

{

	struct sched_domain *sd;

	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 */
@@ -1198,36 +1181,40 @@ static int find_lowest_rq(struct task_struct *task) 
	 * Otherwise, we consult the sched_domains span maps to figure

	 * out which cpu is logically closest to our hot cache data.

	 */

	if (this_cpu == cpu)

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

	if (!cpumask_test_cpu(this_cpu, lowest_mask))

		this_cpu = -1; /* Skip this_cpu opt if not among lowest */



	if (alloc_cpumask_var(&domain_mask, GFP_ATOMIC)) {

	for_each_domain(cpu, sd) {

		if (sd->flags & SD_WAKE_AFFINE) {

			int best_cpu;



				cpumask_and(domain_mask,

					    sched_domain_span(sd),

					    lowest_mask);



				best_cpu = pick_optimal_cpu(this_cpu,

							    domain_mask);

			/*

			 * "this_cpu" is cheaper to preempt than a

			 * remote processor.

			 */

			if (this_cpu != -1 &&

			    cpumask_test_cpu(this_cpu, sched_domain_span(sd)))

				return this_cpu;



				if (best_cpu != -1) {

					free_cpumask_var(domain_mask);

			best_cpu = cpumask_first_and(lowest_mask,

						     sched_domain_span(sd));

			if (best_cpu < nr_cpu_ids)

				return best_cpu;

		}

	}

		}

		free_cpumask_var(domain_mask);

	}



	/*

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

	 * just give the caller *something* to work with from the compatible

	 * locations.

	 */

	return pick_optimal_cpu(this_cpu, lowest_mask);

	if (this_cpu != -1)

		return this_cpu;



	cpu = cpumask_any(lowest_mask);

	if (cpu < nr_cpu_ids)

		return cpu;

	return -1;

}



/* Will lock the rq it finds */