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Commit a8a51d5e authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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sched: persistent average load per task 



Remove the fall-back to SCHED_LOAD_SCALE by remembering the previous value of
cpu_avg_load_per_task() - this is useful because of the hierarchical group
model in which task weight can be much smaller.

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 039a1c41

kernel/sched.c

+12 −13
Original line number Diff line number Diff line
@@ -554,6 +554,8 @@ struct rq { 
	int cpu;

	int online;



	unsigned long avg_load_per_task;



	struct task_struct *migration_thread;

	struct list_head migration_queue;

#endif
@@ -1427,9 +1429,18 @@ static inline void dec_cpu_load(struct rq *rq, unsigned long load) 
#ifdef CONFIG_SMP

static unsigned long source_load(int cpu, int type);

static unsigned long target_load(int cpu, int type);

static unsigned long cpu_avg_load_per_task(int cpu);

static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);



static unsigned long cpu_avg_load_per_task(int cpu)

{

	struct rq *rq = cpu_rq(cpu);



	if (rq->nr_running)

		rq->avg_load_per_task = rq->load.weight / rq->nr_running;



	return rq->avg_load_per_task;

}



#ifdef CONFIG_FAIR_GROUP_SCHED



typedef void (*tg_visitor)(struct task_group *, int, struct sched_domain *);
@@ -2010,18 +2021,6 @@ static unsigned long target_load(int cpu, int type) 
	return max(rq->cpu_load[type-1], total);

}



/*

 * Return the average load per task on the cpu's run queue

 */

static unsigned long cpu_avg_load_per_task(int cpu)

{

	struct rq *rq = cpu_rq(cpu);

	unsigned long total = weighted_cpuload(cpu);

	unsigned long n = rq->nr_running;



	return n ? total / n : SCHED_LOAD_SCALE;

}



/*

 * find_idlest_group finds and returns the least busy CPU group within the

 * domain.