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Commit 396e894d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Revert nohz_ratelimit() for now 



Norbert reported that nohz_ratelimit() causes his laptop to burn about
4W (40%) extra. For now back out the change and see if we can adjust
the power management code to make better decisions.

Reported-by: default avatarNorbert Preining <preining@logic.at>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarMike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent f469461d

include/linux/sched.h

+0 −6
Original line number Diff line number Diff line
@@ -273,17 +273,11 @@ extern cpumask_var_t nohz_cpu_mask; 
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)

extern int select_nohz_load_balancer(int cpu);

extern int get_nohz_load_balancer(void);

extern int nohz_ratelimit(int cpu);

#else

static inline int select_nohz_load_balancer(int cpu)

{

	return 0;

}



static inline int nohz_ratelimit(int cpu)

{

	return 0;

}

#endif



/*

kernel/sched.c

+0 −10
Original line number Diff line number Diff line
@@ -1232,16 +1232,6 @@ void wake_up_idle_cpu(int cpu) 
		smp_send_reschedule(cpu);

}



int nohz_ratelimit(int cpu)

{

	struct rq *rq = cpu_rq(cpu);

	u64 diff = rq->clock - rq->nohz_stamp;



	rq->nohz_stamp = rq->clock;



	return diff < (NSEC_PER_SEC / HZ) >> 1;

}



#endif /* CONFIG_NO_HZ */



static u64 sched_avg_period(void)

kernel/time/tick-sched.c

+1 −1
Original line number Diff line number Diff line
@@ -325,7 +325,7 @@ void tick_nohz_stop_sched_tick(int inidle) 
	} while (read_seqretry(&xtime_lock, seq));



	if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||

	    arch_needs_cpu(cpu) || nohz_ratelimit(cpu)) {

	    arch_needs_cpu(cpu)) {

		next_jiffies = last_jiffies + 1;

		delta_jiffies = 1;

	} else {