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Commit 8f404faa authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt 

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt:
  NOHZ: reevaluate idle sleep length after add_timer_on()
  clocksource: revert: use init_timer_deferrable for clocksource_watchdog
parents 729eb528 06d8308c

include/linux/sched.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -1541,6 +1541,12 @@ static inline void idle_task_exit(void) {} 




extern void sched_idle_next(void);

extern void sched_idle_next(void);





#if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)

extern void wake_up_idle_cpu(int cpu);

#else

static inline void wake_up_idle_cpu(int cpu) { }

#endif



#ifdef CONFIG_SCHED_DEBUG

#ifdef CONFIG_SCHED_DEBUG

extern unsigned int sysctl_sched_latency;

extern unsigned int sysctl_sched_latency;

extern unsigned int sysctl_sched_min_granularity;

extern unsigned int sysctl_sched_min_granularity;

kernel/sched.c

+43 −0
Original line number Original line Diff line number Diff line
@@ -1052,6 +1052,49 @@ static void resched_cpu(int cpu) 
	resched_task(cpu_curr(cpu));

	resched_task(cpu_curr(cpu));

	spin_unlock_irqrestore(&rq->lock, flags);

	spin_unlock_irqrestore(&rq->lock, flags);

}

}



#ifdef CONFIG_NO_HZ

/*

 * When add_timer_on() enqueues a timer into the timer wheel of an

 * idle CPU then this timer might expire before the next timer event

 * which is scheduled to wake up that CPU. In case of a completely

 * idle system the next event might even be infinite time into the

 * future. wake_up_idle_cpu() ensures that the CPU is woken up and

 * leaves the inner idle loop so the newly added timer is taken into

 * account when the CPU goes back to idle and evaluates the timer

 * wheel for the next timer event.

 */

void wake_up_idle_cpu(int cpu)

{

	struct rq *rq = cpu_rq(cpu);



	if (cpu == smp_processor_id())

		return;



	/*

	 * This is safe, as this function is called with the timer

	 * wheel base lock of (cpu) held. When the CPU is on the way

	 * to idle and has not yet set rq->curr to idle then it will

	 * be serialized on the timer wheel base lock and take the new

	 * timer into account automatically.

	 */

	if (rq->curr != rq->idle)

		return;



	/*

	 * We can set TIF_RESCHED on the idle task of the other CPU

	 * lockless. The worst case is that the other CPU runs the

	 * idle task through an additional NOOP schedule()

	 */

	set_tsk_thread_flag(rq->idle, TIF_NEED_RESCHED);



	/* NEED_RESCHED must be visible before we test polling */

	smp_mb();

	if (!tsk_is_polling(rq->idle))

		smp_send_reschedule(cpu);

}

#endif



#else

#else

static void __resched_task(struct task_struct *p, int tif_bit)

static void __resched_task(struct task_struct *p, int tif_bit)

{

{

kernel/time/clocksource.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -174,7 +174,7 @@ static void clocksource_check_watchdog(struct clocksource *cs) 
			if (watchdog)

			if (watchdog)

				del_timer(&watchdog_timer);

				del_timer(&watchdog_timer);

			watchdog = cs;

			watchdog = cs;

			init_timer_deferrable(&watchdog_timer);

			init_timer(&watchdog_timer);

			watchdog_timer.function = clocksource_watchdog;

			watchdog_timer.function = clocksource_watchdog;





			/* Reset watchdog cycles */

			/* Reset watchdog cycles */

kernel/timer.c

+9 −1
Original line number Original line Diff line number Diff line
@@ -451,10 +451,18 @@ void add_timer_on(struct timer_list *timer, int cpu) 
	spin_lock_irqsave(&base->lock, flags);

	spin_lock_irqsave(&base->lock, flags);

	timer_set_base(timer, base);

	timer_set_base(timer, base);

	internal_add_timer(base, timer);

	internal_add_timer(base, timer);

	/*

	 * Check whether the other CPU is idle and needs to be

	 * triggered to reevaluate the timer wheel when nohz is

	 * active. We are protected against the other CPU fiddling

	 * with the timer by holding the timer base lock. This also

	 * makes sure that a CPU on the way to idle can not evaluate

	 * the timer wheel.

	 */

	wake_up_idle_cpu(cpu);

	spin_unlock_irqrestore(&base->lock, flags);

	spin_unlock_irqrestore(&base->lock, flags);

}

}







/**

/**

 * mod_timer - modify a timer's timeout

 * mod_timer - modify a timer's timeout

 * @timer: the timer to be modified

 * @timer: the timer to be modified