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Commit 361833ef authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'sched/clock' into sched/devel

parents 54ef76f3 c300ba25

include/linux/sched.h

+16 −1
Original line number Diff line number Diff line
@@ -1558,13 +1558,28 @@ static inline void sched_clock_idle_sleep_event(void) 
static inline void sched_clock_idle_wakeup_event(u64 delta_ns)

{

}

#else



#ifdef CONFIG_NO_HZ

static inline void sched_clock_tick_stop(int cpu)

{

}



static inline void sched_clock_tick_start(int cpu)

{

}

#endif



#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

extern void sched_clock_init(void);

extern u64 sched_clock_cpu(int cpu);

extern void sched_clock_tick(void);

extern void sched_clock_idle_sleep_event(void);

extern void sched_clock_idle_wakeup_event(u64 delta_ns);

#ifdef CONFIG_NO_HZ

extern void sched_clock_tick_stop(int cpu);

extern void sched_clock_tick_start(int cpu);

#endif

#endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */



/*

 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu

kernel/sched_clock.c

+105 −19
Original line number Diff line number Diff line
@@ -3,6 +3,9 @@ 
 *

 *  Copyright (C) 2008 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>

 *

 *  Updates and enhancements:

 *    Copyright (C) 2008 Red Hat, Inc. Steven Rostedt <srostedt@redhat.com>

 *

 * Based on code by:

 *   Ingo Molnar <mingo@redhat.com>

 *   Guillaume Chazarain <guichaz@gmail.com>
@@ -32,6 +35,11 @@ 


#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK



#define MULTI_SHIFT 15

/* Max is double, Min is 1/2 */

#define MAX_MULTI (2LL << MULTI_SHIFT)

#define MIN_MULTI (1LL << (MULTI_SHIFT-1))



struct sched_clock_data {

	/*

	 * Raw spinlock - this is a special case: this might be called
@@ -40,11 +48,15 @@ struct sched_clock_data { 
	 */

	raw_spinlock_t		lock;



	unsigned long		prev_jiffies;

	unsigned long		tick_jiffies;

	u64			prev_raw;

	u64			tick_raw;

	u64			tick_gtod;

	u64			clock;

	s64			multi;

#ifdef CONFIG_NO_HZ

	int			check_max;

#endif

};



static DEFINE_PER_CPU_SHARED_ALIGNED(struct sched_clock_data, sched_clock_data);
@@ -71,41 +83,91 @@ void sched_clock_init(void) 
		struct sched_clock_data *scd = cpu_sdc(cpu);



		scd->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;

		scd->prev_jiffies = now_jiffies;

		scd->tick_jiffies = now_jiffies;

		scd->prev_raw = 0;

		scd->tick_raw = 0;

		scd->tick_gtod = ktime_now;

		scd->clock = ktime_now;

		scd->multi = 1 << MULTI_SHIFT;

#ifdef CONFIG_NO_HZ

		scd->check_max = 1;

#endif

	}



	sched_clock_running = 1;

}



#ifdef CONFIG_NO_HZ

/*

 * The dynamic ticks makes the delta jiffies inaccurate. This

 * prevents us from checking the maximum time update.

 * Disable the maximum check during stopped ticks.

 */

void sched_clock_tick_stop(int cpu)

{

	struct sched_clock_data *scd = cpu_sdc(cpu);



	scd->check_max = 0;

}



void sched_clock_tick_start(int cpu)

{

	struct sched_clock_data *scd = cpu_sdc(cpu);



	scd->check_max = 1;

}



static int check_max(struct sched_clock_data *scd)

{

	return scd->check_max;

}

#else

static int check_max(struct sched_clock_data *scd)

{

	return 1;

}

#endif /* CONFIG_NO_HZ */



/*

 * update the percpu scd from the raw @now value

 *

 *  - filter out backward motion

 *  - use jiffies to generate a min,max window to clip the raw values

 */

static void __update_sched_clock(struct sched_clock_data *scd, u64 now)

static void __update_sched_clock(struct sched_clock_data *scd, u64 now, u64 *time)

{

	unsigned long now_jiffies = jiffies;

	long delta_jiffies = now_jiffies - scd->prev_jiffies;

	long delta_jiffies = now_jiffies - scd->tick_jiffies;

	u64 clock = scd->clock;

	u64 min_clock, max_clock;

	s64 delta = now - scd->prev_raw;



	WARN_ON_ONCE(!irqs_disabled());

	min_clock = scd->tick_gtod + delta_jiffies * TICK_NSEC;



	/*

	 * At schedule tick the clock can be just under the gtod. We don't

	 * want to push it too prematurely.

	 */

	min_clock = scd->tick_gtod + (delta_jiffies * TICK_NSEC);

	if (min_clock > TICK_NSEC)

		min_clock -= TICK_NSEC / 2;



	if (unlikely(delta < 0)) {

		clock++;

		goto out;

	}



	max_clock = min_clock + TICK_NSEC;

	/*

	 * The clock must stay within a jiffie of the gtod.

	 * But since we may be at the start of a jiffy or the end of one

	 * we add another jiffy buffer.

	 */

	max_clock = scd->tick_gtod + (2 + delta_jiffies) * TICK_NSEC;



	delta *= scd->multi;

	delta >>= MULTI_SHIFT;



	if (unlikely(clock + delta > max_clock)) {

	if (unlikely(clock + delta > max_clock) && check_max(scd)) {

		if (clock < max_clock)

			clock = max_clock;

		else
@@ -118,10 +180,13 @@ static void __update_sched_clock(struct sched_clock_data *scd, u64 now) 
	if (unlikely(clock < min_clock))

		clock = min_clock;



	if (time)

		*time = clock;

	else {

		scd->prev_raw = now;

	scd->prev_jiffies = now_jiffies;

		scd->clock = clock;

	}

}



static void lock_double_clock(struct sched_clock_data *data1,

				struct sched_clock_data *data2)
@@ -160,18 +225,21 @@ u64 sched_clock_cpu(int cpu) 
		now -= my_scd->tick_raw;

		now += scd->tick_raw;



		now -= my_scd->tick_gtod;

		now += scd->tick_gtod;

		now += my_scd->tick_gtod;

		now -= scd->tick_gtod;



		__raw_spin_unlock(&my_scd->lock);



		__update_sched_clock(scd, now, &clock);



		__raw_spin_unlock(&scd->lock);



	} else {

		__raw_spin_lock(&scd->lock);

	}



	__update_sched_clock(scd, now);

		__update_sched_clock(scd, now, NULL);

		clock = scd->clock;



		__raw_spin_unlock(&scd->lock);

	}



	return clock;

}
@@ -179,6 +247,8 @@ u64 sched_clock_cpu(int cpu) 
void sched_clock_tick(void)

{

	struct sched_clock_data *scd = this_scd();

	unsigned long now_jiffies = jiffies;

	s64 mult, delta_gtod, delta_raw;

	u64 now, now_gtod;



	if (unlikely(!sched_clock_running))
@@ -186,18 +256,33 @@ void sched_clock_tick(void) 


	WARN_ON_ONCE(!irqs_disabled());



	now = sched_clock();

	now_gtod = ktime_to_ns(ktime_get());

	now = sched_clock();



	__raw_spin_lock(&scd->lock);

	__update_sched_clock(scd, now);

	__update_sched_clock(scd, now, NULL);

	/*

	 * update tick_gtod after __update_sched_clock() because that will

	 * already observe 1 new jiffy; adding a new tick_gtod to that would

	 * increase the clock 2 jiffies.

	 */

	delta_gtod = now_gtod - scd->tick_gtod;

	delta_raw = now - scd->tick_raw;



	if ((long)delta_raw > 0) {

		mult = delta_gtod << MULTI_SHIFT;

		do_div(mult, delta_raw);

		scd->multi = mult;

		if (scd->multi > MAX_MULTI)

			scd->multi = MAX_MULTI;

		else if (scd->multi < MIN_MULTI)

			scd->multi = MIN_MULTI;

	} else

		scd->multi = 1 << MULTI_SHIFT;



	scd->tick_raw = now;

	scd->tick_gtod = now_gtod;

	scd->tick_jiffies = now_jiffies;

	__raw_spin_unlock(&scd->lock);

}
@@ -227,6 +312,7 @@ void sched_clock_idle_wakeup_event(u64 delta_ns) 
	__raw_spin_lock(&scd->lock);

	scd->prev_raw = now;

	scd->clock += delta_ns;

	scd->multi = 1 << MULTI_SHIFT;

	__raw_spin_unlock(&scd->lock);



	touch_softlockup_watchdog();

kernel/time/tick-sched.c

+2 −0
Original line number Diff line number Diff line
@@ -276,6 +276,7 @@ void tick_nohz_stop_sched_tick(void) 
			ts->tick_stopped = 1;

			ts->idle_jiffies = last_jiffies;

			rcu_enter_nohz();

			sched_clock_tick_stop(cpu);

		}



		/*
@@ -375,6 +376,7 @@ void tick_nohz_restart_sched_tick(void) 
	select_nohz_load_balancer(0);

	now = ktime_get();

	tick_do_update_jiffies64(now);

	sched_clock_tick_start(cpu);

	cpu_clear(cpu, nohz_cpu_mask);



	/*