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Commit ca6d75e6 authored by Vincent Guittot's avatar Vincent Guittot Committed by Ingo Molnar
Browse files

sched: Add struct rq::cpu_capacity_orig 



This new field 'cpu_capacity_orig' reflects the original capacity of a CPU
before being altered by rt tasks and/or IRQ

The cpu_capacity_orig will be used:

  - to detect when the capacity of a CPU has been noticeably reduced so we can
    trig load balance to look for a CPU with better capacity. As an example, we
    can detect when a CPU handles a significant amount of irq
    (with CONFIG_IRQ_TIME_ACCOUNTING) but this CPU is seen as an idle CPU by
    scheduler whereas CPUs, which are really idle, are available.

  - evaluate the available capacity for CFS tasks

Signed-off-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: default avatarMorten Rasmussen <morten.rasmussen@arm.com>
Cc: Morten.Rasmussen@arm.com
Cc: dietmar.eggemann@arm.com
Cc: efault@gmx.de
Cc: linaro-kernel@lists.linaro.org
Cc: nicolas.pitre@linaro.org
Cc: preeti@linux.vnet.ibm.com
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1425052454-25797-7-git-send-email-vincent.guittot@linaro.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b5b4860d

kernel/sched/core.c

+1 −1
Original line number Diff line number Diff line
@@ -7216,7 +7216,7 @@ void __init sched_init(void) 
#ifdef CONFIG_SMP

		rq->sd = NULL;

		rq->rd = NULL;

		rq->cpu_capacity = SCHED_CAPACITY_SCALE;

		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;

		rq->post_schedule = 0;

		rq->active_balance = 0;

		rq->next_balance = jiffies;

kernel/sched/fair.c

+7 −1
Original line number Diff line number Diff line
@@ -4363,6 +4363,11 @@ static unsigned long capacity_of(int cpu) 
	return cpu_rq(cpu)->cpu_capacity;

}



static unsigned long capacity_orig_of(int cpu)

{

	return cpu_rq(cpu)->cpu_capacity_orig;

}



static unsigned long cpu_avg_load_per_task(int cpu)

{

	struct rq *rq = cpu_rq(cpu);
@@ -6040,6 +6045,7 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu) 


	capacity >>= SCHED_CAPACITY_SHIFT;



	cpu_rq(cpu)->cpu_capacity_orig = capacity;

	sdg->sgc->capacity_orig = capacity;



	capacity *= scale_rt_capacity(cpu);
@@ -6094,7 +6100,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu) 
			 * Runtime updates will correct capacity_orig.

			 */

			if (unlikely(!rq->sd)) {

				capacity_orig += capacity_of(cpu);

				capacity_orig += capacity_orig_of(cpu);

				capacity += capacity_of(cpu);

				continue;

			}

kernel/sched/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -615,6 +615,7 @@ struct rq { 
	struct sched_domain *sd;



	unsigned long cpu_capacity;

	unsigned long cpu_capacity_orig;



	unsigned char idle_balance;

	/* For active balancing */