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Commit dcdedb24 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

sched/nohz: Remove the 1 Hz tick code 



Now that the 1Hz tick is offloaded to workqueues, we can safely remove
the residual code that used to handle it locally.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-7-git-send-email-frederic@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent d84b3131

include/linux/sched/nohz.h

+0 −4
Original line number Diff line number Diff line
@@ -37,8 +37,4 @@ extern void wake_up_nohz_cpu(int cpu); 
static inline void wake_up_nohz_cpu(int cpu) { }

#endif



#ifdef CONFIG_NO_HZ_FULL

extern u64 scheduler_tick_max_deferment(void);

#endif



#endif /* _LINUX_SCHED_NOHZ_H */

kernel/sched/core.c

+0 −29
Original line number Diff line number Diff line
@@ -3096,35 +3096,9 @@ void scheduler_tick(void) 
	rq->idle_balance = idle_cpu(cpu);

	trigger_load_balance(rq);

#endif

	rq_last_tick_reset(rq);

}



#ifdef CONFIG_NO_HZ_FULL

/**

 * scheduler_tick_max_deferment

 *

 * Keep at least one tick per second when a single

 * active task is running because the scheduler doesn't

 * yet completely support full dynticks environment.

 *

 * This makes sure that uptime, CFS vruntime, load

 * balancing, etc... continue to move forward, even

 * with a very low granularity.

 *

 * Return: Maximum deferment in nanoseconds.

 */

u64 scheduler_tick_max_deferment(void)

{

	struct rq *rq = this_rq();

	unsigned long next, now = READ_ONCE(jiffies);



	next = rq->last_sched_tick + HZ;



	if (time_before_eq(next, now))

		return 0;



	return jiffies_to_nsecs(next - now);

}



struct tick_work {

	int			cpu;
@@ -6116,9 +6090,6 @@ void __init sched_init(void) 
		rq->last_load_update_tick = jiffies;

		rq->nohz_flags = 0;

#endif

#ifdef CONFIG_NO_HZ_FULL

		rq->last_sched_tick = 0;

#endif

#endif /* CONFIG_SMP */

		hrtick_rq_init(rq);

		atomic_set(&rq->nr_iowait, 0);

kernel/sched/idle_task.c

+0 −1
Original line number Diff line number Diff line
@@ -48,7 +48,6 @@ dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags) 


static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)

{

	rq_last_tick_reset(rq);

}



/*

kernel/sched/sched.h

+1 −10
Original line number Diff line number Diff line
@@ -727,9 +727,7 @@ struct rq { 
#endif /* CONFIG_SMP */

	unsigned long nohz_flags;

#endif /* CONFIG_NO_HZ_COMMON */

#ifdef CONFIG_NO_HZ_FULL

	unsigned long last_sched_tick;

#endif



	/* capture load from *all* tasks on this cpu: */

	struct load_weight load;

	unsigned long nr_load_updates;
@@ -1626,13 +1624,6 @@ static inline void sub_nr_running(struct rq *rq, unsigned count) 
	sched_update_tick_dependency(rq);

}



static inline void rq_last_tick_reset(struct rq *rq)

{

#ifdef CONFIG_NO_HZ_FULL

	rq->last_sched_tick = jiffies;

#endif

}



extern void update_rq_clock(struct rq *rq);



extern void activate_task(struct rq *rq, struct task_struct *p, int flags);

kernel/time/tick-sched.c

+0 −6
Original line number Diff line number Diff line
@@ -748,12 +748,6 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, 
		delta = KTIME_MAX;

	}



#ifdef CONFIG_NO_HZ_FULL

	/* Limit the tick delta to the maximum scheduler deferment */

	if (!ts->inidle)

		delta = min(delta, scheduler_tick_max_deferment());

#endif



	/* Calculate the next expiry time */

	if (delta < (KTIME_MAX - basemono))

		expires = basemono + delta;