Commit 0a74bef8 authored by Paul Turner's avatar Paul Turner Committed by Ingo Molnar
Browse files

sched: Add an rq migration call-back to sched_class 



Since we are now doing bottom up load accumulation we need explicit
notification when a task has been re-parented so that the old hierarchy can be
updated.

Adds: migrate_task_rq(struct task_struct *p, int next_cpu)

(The alternative is to do this out of __set_task_cpu, but it was suggested that
this would be a cleaner encapsulation.)

Signed-off-by: default avatarPaul Turner <pjt@google.com>
Reviewed-by: default avatarBen Segall <bsegall@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120823141506.660023400@google.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9ee474f5

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1061,6 +1061,7 @@ struct sched_class { 


#ifdef CONFIG_SMP

	int  (*select_task_rq)(struct task_struct *p, int sd_flag, int flags);

	void (*migrate_task_rq)(struct task_struct *p, int next_cpu);



	void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);

	void (*post_schedule) (struct rq *this_rq);

kernel/sched/core.c

+2 −0
Original line number Diff line number Diff line
@@ -952,6 +952,8 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 
	trace_sched_migrate_task(p, new_cpu);



	if (task_cpu(p) != new_cpu) {

		if (p->sched_class->migrate_task_rq)

			p->sched_class->migrate_task_rq(p, new_cpu);

		p->se.nr_migrations++;

		perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);

	}

kernel/sched/fair.c

+12 −0
Original line number Diff line number Diff line
@@ -3047,6 +3047,17 @@ unlock: 


	return new_cpu;

}



/*

 * Called immediately before a task is migrated to a new cpu; task_cpu(p) and

 * cfs_rq_of(p) references at time of call are still valid and identify the

 * previous cpu.  However, the caller only guarantees p->pi_lock is held; no

 * other assumptions, including the state of rq->lock, should be made.

 */

static void

migrate_task_rq_fair(struct task_struct *p, int next_cpu)

{

}

#endif /* CONFIG_SMP */



static unsigned long
@@ -5607,6 +5618,7 @@ const struct sched_class fair_sched_class = { 


#ifdef CONFIG_SMP

	.select_task_rq		= select_task_rq_fair,

	.migrate_task_rq	= migrate_task_rq_fair,



	.rq_online		= rq_online_fair,

	.rq_offline		= rq_offline_fair,

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