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Commit 103638d9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: fix wakeup granularity and buddy granularity 



Uncouple buddy selection from wakeup granularity.

The initial idea was that buddies could run ahead as far as a normal task
can - do this by measuring a pair 'slice' just as we do for a normal task.

This means we can drop the wakeup_granularity back to 5ms.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 76a2a6ee

kernel/sched.c

+1 −0
Original line number Diff line number Diff line
@@ -375,6 +375,7 @@ struct cfs_rq { 


	u64 exec_clock;

	u64 min_vruntime;

	u64 pair_start;



	struct rb_root tasks_timeline;

	struct rb_node *rb_leftmost;

kernel/sched_fair.c

+7 −8
Original line number Diff line number Diff line
@@ -63,13 +63,13 @@ unsigned int __read_mostly sysctl_sched_compat_yield; 


/*

 * SCHED_OTHER wake-up granularity.

 * (default: 10 msec * (1 + ilog(ncpus)), units: nanoseconds)

 * (default: 5 msec * (1 + ilog(ncpus)), units: nanoseconds)

 *

 * This option delays the preemption effects of decoupled workloads

 * and reduces their over-scheduling. Synchronous workloads will still

 * have immediate wakeup/sleep latencies.

 */

unsigned int sysctl_sched_wakeup_granularity = 10000000UL;

unsigned int sysctl_sched_wakeup_granularity = 5000000UL;



const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
@@ -813,17 +813,16 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) 
	se->prev_sum_exec_runtime = se->sum_exec_runtime;

}



static int

wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);



static struct sched_entity *

pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	if (!cfs_rq->next)

		return se;

	struct rq *rq = rq_of(cfs_rq);

	u64 pair_slice = rq->clock - cfs_rq->pair_start;



	if (wakeup_preempt_entity(cfs_rq->next, se) != 0)

	if (!cfs_rq->next || pair_slice > sched_slice(cfs_rq, cfs_rq->next)) {

		cfs_rq->pair_start = rq->clock;

		return se;

	}



	return cfs_rq->next;

}