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Commit ea6a3247 authored by Lingutla Chandrasekhar's avatar Lingutla Chandrasekhar
Browse files

Revert "time: Run deferrable timers on other CPUs when tick_do_timer_cpu is busy" 



Only Watchdog was using deferrable timers, but it is not using deferrable
any more. So reverting the change and let tick_do_timer_cpu run the
deferrable timers.

This reverts 'commit 4fe122d7 ("time: Run deferrable timers on
other CPUs when tick_do_timer_cpu is busy")'

Change-Id: I59fcd7cdb216230864cd948d242d563ade6437c8
Signed-off-by: default avatarLingutla Chandrasekhar <clingutla@codeaurora.org>
parent 3ea1f835

include/linux/interrupt.h

+0 −8
Original line number Diff line number Diff line
@@ -14,7 +14,6 @@ 
#include <linux/hrtimer.h>

#include <linux/kref.h>

#include <linux/workqueue.h>

#include <linux/sched.h>



#include <linux/atomic.h>

#include <asm/ptrace.h>
@@ -499,13 +498,6 @@ static inline struct task_struct *this_cpu_ksoftirqd(void) 
	return this_cpu_read(ksoftirqd);

}



static inline bool ksoftirqd_running_on(int cpu)

{

	struct task_struct *tsk = per_cpu(ksoftirqd, cpu);



	return tsk && (tsk->state == TASK_RUNNING);

}



/* Tasklets --- multithreaded analogue of BHs.



   Main feature differing them of generic softirqs: tasklet

kernel/time/timer.c

+4 −24
Original line number Diff line number Diff line
@@ -208,6 +208,7 @@ struct timer_base { 


static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]);

struct timer_base timer_base_deferrable;

static atomic_t deferrable_pending;



#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)

unsigned int sysctl_timer_migration = 1;
@@ -1488,8 +1489,6 @@ static u64 cmp_next_hrtimer_event(u64 basem, u64 expires) 




#ifdef CONFIG_SMP

static atomic_t deferrable_pending;



/*

 * check_pending_deferrable_timers - Check for unbound deferrable timer expiry

 * @cpu - Current CPU
@@ -1670,27 +1669,6 @@ static inline void __run_timers(struct timer_base *base) 
	spin_unlock_irq(&base->lock);

}



#ifdef CONFIG_SMP

static inline bool should_this_cpu_run_deferrable_timers(void)

{

	int tick_cpu = READ_ONCE(tick_do_timer_cpu);



	if (atomic_cmpxchg(&deferrable_pending, 1, 0) &&

			tick_cpu == TICK_DO_TIMER_NONE)

		return true;



	if (tick_cpu == smp_processor_id())

		return true;



	return (tick_cpu >= 0 && ksoftirqd_running_on(tick_cpu));

}

#else

static inline bool should_this_cpu_run_deferrable_timers(void)

{

	return true;

}

#endif



/*

 * This function runs timers and the timer-tq in bottom half context.

 */
@@ -1715,7 +1693,9 @@ static __latent_entropy void run_timer_softirq(struct softirq_action *h) 
	if (IS_ENABLED(CONFIG_NO_HZ_COMMON))

		__run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));



	if (should_this_cpu_run_deferrable_timers())

	if ((atomic_cmpxchg(&deferrable_pending, 1, 0) &&

		tick_do_timer_cpu == TICK_DO_TIMER_NONE) ||

		tick_do_timer_cpu == smp_processor_id())

		__run_timers(&timer_base_deferrable);

}