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Commit 63fc81d8 authored by Joonwoo Park's avatar Joonwoo Park
Browse files

Revert "hrtimer: reprogram remote CPU's timer hardware" 



Revert commit 301bc715 ("hrtimer: reprogram remote CPU's timer
hardware") which caused power and performance regression by waking up
remote CPU unnecessarily.

CRs-fixed: 931853
Change-Id: I4c513395b20b2a007d9ea839c20ac558bfc8e932
Signed-off-by: default avatarJoonwoo Park <joonwoop@codeaurora.org>
parent bdac6adb

kernel/time/hrtimer.c

+40 −38
Original line number Original line Diff line number Diff line
@@ -49,7 +49,6 @@ 
#include <linux/sched/deadline.h>

#include <linux/sched/deadline.h>

#include <linux/timer.h>

#include <linux/timer.h>

#include <linux/freezer.h>

#include <linux/freezer.h>

#include <linux/irq_work.h>





#include <asm/uaccess.h>

#include <asm/uaccess.h>
@@ -168,6 +167,29 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, 
	}

	}

}

}





/*

 * With HIGHRES=y we do not migrate the timer when it is expiring

 * before the next event on the target cpu because we cannot reprogram

 * the target cpu hardware and we would cause it to fire late.

 *

 * Called with cpu_base->lock of target cpu held.

 */

static int

hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)

{

#ifdef CONFIG_HIGH_RES_TIMERS

	ktime_t expires;



	if (!new_base->cpu_base->hres_active)

		return 0;



	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);

	return expires.tv64 <= new_base->cpu_base->expires_next.tv64;

#else

	return 0;

#endif

}



/*

/*

 * Switch the timer base to the current CPU when possible.

 * Switch the timer base to the current CPU when possible.

 */

 */
@@ -177,9 +199,11 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, 
{

{

	struct hrtimer_clock_base *new_base;

	struct hrtimer_clock_base *new_base;

	struct hrtimer_cpu_base *new_cpu_base;

	struct hrtimer_cpu_base *new_cpu_base;

	int this_cpu = smp_processor_id();

	int cpu = get_nohz_timer_target(pinned);

	int cpu = get_nohz_timer_target(pinned);

	int basenum = base->index;

	int basenum = base->index;





again:

	new_cpu_base = &per_cpu(hrtimer_bases, cpu);

	new_cpu_base = &per_cpu(hrtimer_bases, cpu);

	new_base = &new_cpu_base->clock_base[basenum];

	new_base = &new_cpu_base->clock_base[basenum];
@@ -200,7 +224,20 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, 
		timer->base = NULL;

		timer->base = NULL;

		raw_spin_unlock(&base->cpu_base->lock);

		raw_spin_unlock(&base->cpu_base->lock);

		raw_spin_lock(&new_base->cpu_base->lock);

		raw_spin_lock(&new_base->cpu_base->lock);



		if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {

			cpu = this_cpu;

			raw_spin_unlock(&new_base->cpu_base->lock);

			raw_spin_lock(&base->cpu_base->lock);

			timer->base = base;

			goto again;

		}

		timer->base = new_base;

		timer->base = new_base;

	} else {

		if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {

			cpu = this_cpu;

			goto again;

		}

	}

	}

	return new_base;

	return new_base;

}

}
@@ -620,20 +657,6 @@ static void retrigger_next_event(void *arg) 
	raw_spin_unlock(&base->lock);

	raw_spin_unlock(&base->lock);

}

}





#ifdef CONFIG_SMP

static void raise_hrtimer_softirq(struct irq_work *arg)

{

	if (!hrtimer_hres_active())

		return;



	raise_softirq(HRTIMER_SOFTIRQ);

}



static DEFINE_PER_CPU(struct irq_work, hrtimer_kick_work) = {

	.func = raise_hrtimer_softirq,

};

#endif



/*

/*

 * Switch to high resolution mode

 * Switch to high resolution mode

 */

 */
@@ -698,22 +721,6 @@ static inline void retrigger_next_event(void *arg) { } 




#endif /* CONFIG_HIGH_RES_TIMERS */

#endif /* CONFIG_HIGH_RES_TIMERS */





#ifdef CONFIG_SMP



static void kick_remote_cpu(int cpu)

{

	get_cpu();

	if (cpu_online(cpu))

		irq_work_queue_on(&per_cpu(hrtimer_kick_work, cpu), cpu);

	put_cpu();

}



#else



static inline void kick_remote_cpu(int cpu) { }



#endif



/*

/*

 * Clock realtime was set

 * Clock realtime was set

 *

 *
@@ -932,7 +939,7 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, 
{

{

	struct hrtimer_clock_base *base, *new_base;

	struct hrtimer_clock_base *base, *new_base;

	unsigned long flags;

	unsigned long flags;

	int ret, leftmost, kick = 0, cpu;

	int ret, leftmost;





	base = lock_hrtimer_base(timer, &flags);

	base = lock_hrtimer_base(timer, &flags);
@@ -979,6 +986,7 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, 
		 * Only allow reprogramming if the new base is on this CPU.

		 * Only allow reprogramming if the new base is on this CPU.

		 * (it might still be on another CPU if the timer was pending)

		 * (it might still be on another CPU if the timer was pending)

		 *

		 *

		 * XXX send_remote_softirq() ?

		 */

		 */

		if (wakeup) {

		if (wakeup) {

			/*

			/*
@@ -992,16 +1000,10 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, 
		} else {

		} else {

			__raise_softirq_irqoff(HRTIMER_SOFTIRQ);

			__raise_softirq_irqoff(HRTIMER_SOFTIRQ);

		}

		}

	} else {

		cpu = new_base->cpu_base->cpu;

		kick = (leftmost && (cpu != smp_processor_id()));

	}

	}





	unlock_hrtimer_base(timer, &flags);

	unlock_hrtimer_base(timer, &flags);





	if (kick)

		kick_remote_cpu(cpu);



	return ret;

	return ret;

}

}

EXPORT_SYMBOL_GPL(__hrtimer_start_range_ns);

EXPORT_SYMBOL_GPL(__hrtimer_start_range_ns);