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Commit 95833c83 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[PATCH] x86_64: Add idle notifiers 



This adds a new notifier chain that is called with IDLE_START
when a CPU goes idle and IDLE_END when it goes out of idle.
The context can be idle thread or interrupt context.

Since we cannot rely on MONITOR/MWAIT existing the idle
end check currently has to be done in all interrupt
handlers.

They were originally inspired by the similar s390 implementation.

They have a variety of applications:
- They will be needed for CONFIG_NO_IDLE_HZ
- They can be used for oprofile to fix up the missing time
in idle when performance counters don't tick.
- They can be used for better C state management in ACPI
- They could be used for microstate accounting.

This is just infrastructure so far, no users.

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6b050f80

arch/x86_64/kernel/apic.c

+4 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <asm/pgalloc.h>

#include <asm/mach_apic.h>

#include <asm/nmi.h>

#include <asm/idle.h>



int apic_verbosity;
@@ -922,6 +923,7 @@ void smp_apic_timer_interrupt(struct pt_regs *regs) 
	 * Besides, if we don't timer interrupts ignore the global

	 * interrupt lock, which is the WrongThing (tm) to do.

	 */

	exit_idle();

	irq_enter();

	smp_local_timer_interrupt(regs);

	irq_exit();
@@ -981,6 +983,7 @@ __init int oem_force_hpet_timer(void) 
asmlinkage void smp_spurious_interrupt(void)

{

	unsigned int v;

	exit_idle();

	irq_enter();

	/*

	 * Check if this really is a spurious interrupt and ACK it
@@ -1016,6 +1019,7 @@ asmlinkage void smp_error_interrupt(void) 
{

	unsigned int v, v1;



	exit_idle();

	irq_enter();

	/* First tickle the hardware, only then report what went on. -- REW */

	v = apic_read(APIC_ESR);

arch/x86_64/kernel/irq.c

+2 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/delay.h>

#include <asm/uaccess.h>

#include <asm/io_apic.h>

#include <asm/idle.h>



atomic_t irq_err_count;

#ifdef CONFIG_X86_IO_APIC
@@ -98,6 +99,7 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs) 
	/* high bits used in ret_from_ code  */

	unsigned irq = regs->orig_rax & 0xff;



	exit_idle();

	irq_enter();



	__do_IRQ(irq, regs);

arch/x86_64/kernel/mce_amd.c

+2 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <asm/mce.h>

#include <asm/msr.h>

#include <asm/percpu.h>

#include <asm/idle.h>



#define PFX "mce_threshold: "

#define VERSION "version 1.00.9"
@@ -140,6 +141,7 @@ asmlinkage void mce_threshold_interrupt(void) 
	struct mce m;



	ack_APIC_irq();

	exit_idle();

	irq_enter();



	memset(&m, 0, sizeof(m));

arch/x86_64/kernel/mce_intel.c

+2 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <asm/msr.h>

#include <asm/mce.h>

#include <asm/hw_irq.h>

#include <asm/idle.h>



static DEFINE_PER_CPU(unsigned long, next_check);
@@ -19,6 +20,7 @@ asmlinkage void smp_thermal_interrupt(void) 


	ack_APIC_irq();



	exit_idle();

	irq_enter();

	if (time_before(jiffies, __get_cpu_var(next_check)))

		goto done;

arch/x86_64/kernel/process.c

+48 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <linux/utsname.h>

#include <linux/random.h>

#include <linux/kprobes.h>

#include <linux/notifier.h>



#include <asm/uaccess.h>

#include <asm/pgtable.h>
@@ -50,6 +51,7 @@ 
#include <asm/desc.h>

#include <asm/proto.h>

#include <asm/ia32.h>

#include <asm/idle.h>



asmlinkage extern void ret_from_fork(void);
@@ -64,6 +66,50 @@ EXPORT_SYMBOL(boot_option_idle_override); 
void (*pm_idle)(void);

static DEFINE_PER_CPU(unsigned int, cpu_idle_state);



static struct notifier_block *idle_notifier;

static DEFINE_SPINLOCK(idle_notifier_lock);



void idle_notifier_register(struct notifier_block *n)

{

	unsigned long flags;

	spin_lock_irqsave(&idle_notifier_lock, flags);

	notifier_chain_register(&idle_notifier, n);

	spin_unlock_irqrestore(&idle_notifier_lock, flags);

}

EXPORT_SYMBOL_GPL(idle_notifier_register);



void idle_notifier_unregister(struct notifier_block *n)

{

	unsigned long flags;

	spin_lock_irqsave(&idle_notifier_lock, flags);

	notifier_chain_unregister(&idle_notifier, n);

	spin_unlock_irqrestore(&idle_notifier_lock, flags);

}

EXPORT_SYMBOL(idle_notifier_unregister);



enum idle_state { CPU_IDLE, CPU_NOT_IDLE };

static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;



void enter_idle(void)

{

	__get_cpu_var(idle_state) = CPU_IDLE;

	notifier_call_chain(&idle_notifier, IDLE_START, NULL);

}



static void __exit_idle(void)

{

	__get_cpu_var(idle_state) = CPU_NOT_IDLE;

	notifier_call_chain(&idle_notifier, IDLE_END, NULL);

}



/* Called from interrupts to signify idle end */

void exit_idle(void)

{

	if (current->pid | read_pda(irqcount))

		return;

	__exit_idle();

}



/*

 * We use this if we don't have any better

 * idle routine..
@@ -180,7 +226,9 @@ void cpu_idle (void) 
				idle = default_idle;

			if (cpu_is_offline(smp_processor_id()))

				play_dead();

			enter_idle();

			idle();

			__exit_idle();

		}



		preempt_enable_no_resched();