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Commit 2e62c474 authored by Vincent Guittot's avatar Vincent Guittot Committed by Ingo Molnar
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sched/fair: Remove #ifdefs from scale_rt_capacity() 



Reuse cpu_util_irq() that has been defined for schedutil and set irq util
to 0 when !CONFIG_IRQ_TIME_ACCOUNTING.

But the compiler is not able to optimize the sequence (at least with
aarch64 GCC 7.2.1):

	free *= (max - irq);
	free /= max;

when irq is fixed to 0

Add a new inline function scale_irq_capacity() that will scale utilization
when irq is accounted. Reuse this funciton in schedutil which applies
similar formula.

Suggested-by: default avatarIngo Molnar <mingo@redhat.com>
Signed-off-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1532001606-6689-1-git-send-email-vincent.guittot@linaro.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4765096f

kernel/sched/core.c

+1 −1
Original line number Diff line number Diff line
@@ -177,7 +177,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) 


	rq->clock_task += delta;



#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)

#ifdef HAVE_SCHED_AVG_IRQ

	if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))

		update_irq_load_avg(rq, irq_delta + steal);

#endif

kernel/sched/cpufreq_schedutil.c

+1 −2
Original line number Diff line number Diff line
@@ -247,8 +247,7 @@ static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu) 
	 *   U' = irq + ------- * U

	 *                max

	 */

	util *= (max - irq);

	util /= max;

	util = scale_irq_capacity(util, irq, max);

	util += irq;



	/*

kernel/sched/fair.c

+3 −10
Original line number Diff line number Diff line
@@ -7551,16 +7551,12 @@ static unsigned long scale_rt_capacity(int cpu) 
	struct rq *rq = cpu_rq(cpu);

	unsigned long max = arch_scale_cpu_capacity(NULL, cpu);

	unsigned long used, free;

#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)

	unsigned long irq;

#endif



#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)

	irq = READ_ONCE(rq->avg_irq.util_avg);

	irq = cpu_util_irq(rq);



	if (unlikely(irq >= max))

		return 1;

#endif



	used = READ_ONCE(rq->avg_rt.util_avg);

	used += READ_ONCE(rq->avg_dl.util_avg);
@@ -7569,11 +7565,8 @@ static unsigned long scale_rt_capacity(int cpu) 
		return 1;



	free = max - used;

#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)

	free *= (max - irq);

	free /= max;

#endif

	return free;



	return scale_irq_capacity(free, irq, max);

}



static void update_cpu_capacity(struct sched_domain *sd, int cpu)

kernel/sched/sched.h

+18 −2
Original line number Diff line number Diff line
@@ -856,6 +856,7 @@ struct rq { 
	struct sched_avg	avg_rt;

	struct sched_avg	avg_dl;

#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)

#define HAVE_SCHED_AVG_IRQ

	struct sched_avg	avg_irq;

#endif

	u64			idle_stamp;
@@ -2210,17 +2211,32 @@ static inline unsigned long cpu_util_rt(struct rq *rq) 
{

	return READ_ONCE(rq->avg_rt.util_avg);

}

#endif



#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)

#ifdef HAVE_SCHED_AVG_IRQ

static inline unsigned long cpu_util_irq(struct rq *rq)

{

	return rq->avg_irq.util_avg;

}



static inline

unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned long max)

{

	util *= (max - irq);

	util /= max;



	return util;



}

#else

static inline unsigned long cpu_util_irq(struct rq *rq)

{

	return 0;

}



#endif

static inline

unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned long max)

{

	return util;

}

#endif