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Commit 6ddd2a27 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

x86: simplify idle selection 



default_idle is selected in cpu_idle(), when no other idle routine is
selected. Select it in select_idle_routine() when mwait is not
selected.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9e26d842

arch/x86/kernel/process.c

+7 −11
Original line number Original line Diff line number Diff line
@@ -139,27 +139,23 @@ static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c) 




void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)

void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)

{

{

	static int selected;



	if (selected)

		return;

#ifdef CONFIG_X86_SMP

#ifdef CONFIG_X86_SMP

	if (pm_idle == poll_idle && smp_num_siblings > 1) {

	if (pm_idle == poll_idle && smp_num_siblings > 1) {

		printk(KERN_WARNING "WARNING: polling idle and HT enabled,"

		printk(KERN_WARNING "WARNING: polling idle and HT enabled,"

			" performance may degrade.\n");

			" performance may degrade.\n");

	}

	}

#endif

#endif

	if (pm_idle)

		return;



	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {

	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {

		/*

		/*

		 * Skip, if setup has overridden idle.

		 * One CPU supports mwait => All CPUs supports mwait

		 * One CPU supports mwait => All CPUs supports mwait

		 */

		 */

		if (!pm_idle) {

		printk(KERN_INFO "using mwait in idle threads.\n");

		printk(KERN_INFO "using mwait in idle threads.\n");

		pm_idle = mwait_idle;

		pm_idle = mwait_idle;

		}

	} else

	}

		pm_idle = default_idle;

	selected = 1;

}

}





static int __init idle_setup(char *str)

static int __init idle_setup(char *str)

arch/x86/kernel/process_32.c

+1 −6
Original line number Original line Diff line number Diff line
@@ -168,24 +168,19 @@ void cpu_idle(void) 
	while (1) {

	while (1) {

		tick_nohz_stop_sched_tick();

		tick_nohz_stop_sched_tick();

		while (!need_resched()) {

		while (!need_resched()) {

			void (*idle)(void);





			check_pgt_cache();

			check_pgt_cache();

			rmb();

			rmb();

			idle = pm_idle;





			if (rcu_pending(cpu))

			if (rcu_pending(cpu))

				rcu_check_callbacks(cpu, 0);

				rcu_check_callbacks(cpu, 0);





			if (!idle)

				idle = default_idle;



			if (cpu_is_offline(cpu))

			if (cpu_is_offline(cpu))

				play_dead();

				play_dead();





			local_irq_disable();

			local_irq_disable();

			__get_cpu_var(irq_stat).idle_timestamp = jiffies;

			__get_cpu_var(irq_stat).idle_timestamp = jiffies;

			idle();

			pm_idle();

		}

		}

		tick_nohz_restart_sched_tick();

		tick_nohz_restart_sched_tick();

		preempt_enable_no_resched();

		preempt_enable_no_resched();

arch/x86/kernel/process_64.c

+2 −5
Original line number Original line Diff line number Diff line
@@ -150,12 +150,9 @@ void cpu_idle(void) 
	while (1) {

	while (1) {

		tick_nohz_stop_sched_tick();

		tick_nohz_stop_sched_tick();

		while (!need_resched()) {

		while (!need_resched()) {

			void (*idle)(void);





			rmb();

			rmb();

			idle = pm_idle;



			if (!idle)

				idle = default_idle;

			if (cpu_is_offline(smp_processor_id()))

			if (cpu_is_offline(smp_processor_id()))

				play_dead();

				play_dead();

			/*

			/*
@@ -165,7 +162,7 @@ void cpu_idle(void) 
			 */

			 */

			local_irq_disable();

			local_irq_disable();

			enter_idle();

			enter_idle();

			idle();

			pm_idle();

			/* In many cases the interrupt that ended idle

			/* In many cases the interrupt that ended idle

			   has already called exit_idle. But some idle

			   has already called exit_idle. But some idle

			   loops can be woken up without interrupt. */

			   loops can be woken up without interrupt. */