Commit 00aec93d authored by Gregory Haskins's avatar Gregory Haskins Committed by Ingo Molnar
Browse files

sched: Fully integrate cpus_active_map and root-domain code 



Reflect "active" cpus in the rq->rd->online field, instead of
the online_map.

The motivation is that things that use the root-domain code
(such as cpupri) only care about cpus classified as "active"
anyway. By synchronizing the root-domain state with the active
map, we allow several optimizations.

For instance, we can remove an extra cpumask_and from the
scheduler hotpath by utilizing rq->rd->online (since it is now
a cached version of cpu_active_map & rq->rd->span).

Signed-off-by: default avatarGregory Haskins <ghaskins@novell.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarMax Krasnyansky <maxk@qualcomm.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090730145723.25226.24493.stgit@dev.haskins.net>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3f029d3c

kernel/sched.c

+1 −1
Original line number Diff line number Diff line
@@ -7927,7 +7927,7 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd) 
	rq->rd = rd;



	cpumask_set_cpu(rq->cpu, rd->span);

	if (cpumask_test_cpu(rq->cpu, cpu_online_mask))

	if (cpumask_test_cpu(rq->cpu, cpu_active_mask))

		set_rq_online(rq);



	spin_unlock_irqrestore(&rq->lock, flags);

kernel/sched_fair.c

+7 −3
Original line number Diff line number Diff line
@@ -1046,17 +1046,21 @@ static void yield_task_fair(struct rq *rq) 
 * search starts with cpus closest then further out as needed,

 * so we always favor a closer, idle cpu.

 * Domains may include CPUs that are not usable for migration,

 * hence we need to mask them out (cpu_active_mask)

 * hence we need to mask them out (rq->rd->online)

 *

 * Returns the CPU we should wake onto.

 */

#if defined(ARCH_HAS_SCHED_WAKE_IDLE)



#define cpu_rd_active(cpu, rq) cpumask_test_cpu(cpu, rq->rd->online)



static int wake_idle(int cpu, struct task_struct *p)

{

	struct sched_domain *sd;

	int i;

	unsigned int chosen_wakeup_cpu;

	int this_cpu;

	struct rq *task_rq = task_rq(p);



	/*

	 * At POWERSAVINGS_BALANCE_WAKEUP level, if both this_cpu and prev_cpu
@@ -1089,10 +1093,10 @@ static int wake_idle(int cpu, struct task_struct *p) 
	for_each_domain(cpu, sd) {

		if ((sd->flags & SD_WAKE_IDLE)

		    || ((sd->flags & SD_WAKE_IDLE_FAR)

			&& !task_hot(p, task_rq(p)->clock, sd))) {

			&& !task_hot(p, task_rq->clock, sd))) {

			for_each_cpu_and(i, sched_domain_span(sd),

					 &p->cpus_allowed) {

				if (cpu_active(i) && idle_cpu(i)) {

				if (cpu_rd_active(i, task_rq) && idle_cpu(i)) {

					if (i != task_cpu(p)) {

						schedstat_inc(p,

						       se.nr_wakeups_idle);

kernel/sched_rt.c

+0 −7
Original line number Diff line number Diff line
@@ -1172,13 +1172,6 @@ static int find_lowest_rq(struct task_struct *task) 
	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))

		return -1; /* No targets found */



	/*

	 * Only consider CPUs that are usable for migration.

	 * I guess we might want to change cpupri_find() to ignore those

	 * in the first place.

	 */

	cpumask_and(lowest_mask, lowest_mask, cpu_active_mask);



	/*

	 * At this point we have built a mask of cpus representing the

	 * lowest priority tasks in the system.  Now we want to elect

CRA Git | Maintained and supported by SUSTech CRA and CCSE