Commit c1cc017c authored by Alex Shi's avatar Alex Shi Committed by Ingo Molnar
Browse files

sched/nohz: Clean up select_nohz_load_balancer() 



There is no load_balancer to be selected now. It just sets the
state of the nohz tick to stop.

So rename the function, pass the 'cpu' as a parameter and then
remove the useless call from tick_nohz_restart_sched_tick().

[ s/set_nohz_tick_stopped/nohz_balance_enter_idle/g
  s/clear_nohz_tick_stopped/nohz_balance_exit_idle/g ]
Signed-off-by: default avatarAlex Shi <alex.shi@intel.com>
Acked-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347261059-24747-1-git-send-email-alex.shi@intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 08bedae1

include/linux/sched.h

+2 −2
Original line number Diff line number Diff line
@@ -273,11 +273,11 @@ extern void init_idle_bootup_task(struct task_struct *idle); 
extern int runqueue_is_locked(int cpu);



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

extern void select_nohz_load_balancer(int stop_tick);

extern void nohz_balance_enter_idle(int cpu);

extern void set_cpu_sd_state_idle(void);

extern int get_nohz_timer_target(void);

#else

static inline void select_nohz_load_balancer(int stop_tick) { }

static inline void nohz_balance_enter_idle(int cpu) { }

static inline void set_cpu_sd_state_idle(void) { }

#endif

kernel/sched/fair.c

+10 −15
Original line number Diff line number Diff line
@@ -4603,7 +4603,7 @@ static void nohz_balancer_kick(int cpu) 
	return;

}



static inline void clear_nohz_tick_stopped(int cpu)

static inline void nohz_balance_exit_idle(int cpu)

{

	if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {

		cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
@@ -4643,20 +4643,17 @@ void set_cpu_sd_state_idle(void) 
}



/*

 * This routine will record that this cpu is going idle with tick stopped.

 * This routine will record that the cpu is going idle with tick stopped.

 * This info will be used in performing idle load balancing in the future.

 */

void select_nohz_load_balancer(int stop_tick)

void nohz_balance_enter_idle(int cpu)

{

	int cpu = smp_processor_id();



	/*

	 * If this cpu is going down, then nothing needs to be done.

	 */

	if (!cpu_active(cpu))

		return;



	if (stop_tick) {

	if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))

		return;
@@ -4664,15 +4661,13 @@ void select_nohz_load_balancer(int stop_tick) 
	atomic_inc(&nohz.nr_cpus);

	set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));

}

	return;

}



static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,

					unsigned long action, void *hcpu)

{

	switch (action & ~CPU_TASKS_FROZEN) {

	case CPU_DYING:

		clear_nohz_tick_stopped(smp_processor_id());

		nohz_balance_exit_idle(smp_processor_id());

		return NOTIFY_OK;

	default:

		return NOTIFY_DONE;
@@ -4833,7 +4828,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) 
	* busy tick after returning from idle, we will update the busy stats.

	*/

	set_cpu_sd_state_busy();

	clear_nohz_tick_stopped(cpu);

	nohz_balance_exit_idle(cpu);



	/*

	 * None are in tickless mode and hence no need for NOHZ idle load

kernel/time/tick-sched.c

+1 −2
Original line number Diff line number Diff line
@@ -372,7 +372,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, 
		 * the scheduler tick in nohz_restart_sched_tick.

		 */

		if (!ts->tick_stopped) {

			select_nohz_load_balancer(1);

			nohz_balance_enter_idle(cpu);

			calc_load_enter_idle();



			ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
@@ -569,7 +569,6 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) 
static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)

{

	/* Update jiffies first */

	select_nohz_load_balancer(0);

	tick_do_update_jiffies64(now);

	update_cpu_load_nohz();

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