diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index 40cbd60..628aebf 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -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 @@
 	 * 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 @@
 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 @@
 {
 	unsigned int v, v1;
 
+	exit_idle();
 	irq_enter();
 	/* First tickle the hardware, only then report what went on. -- REW */
 	v = apic_read(APIC_ESR);
diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
index d6a04a8..8bf57f7 100644
--- a/arch/x86_64/kernel/irq.c
+++ b/arch/x86_64/kernel/irq.c
@@ -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 @@
 	/* high bits used in ret_from_ code  */
 	unsigned irq = regs->orig_rax & 0xff;
 
+	exit_idle();
 	irq_enter();
 
 	__do_IRQ(irq, regs);
diff --git a/arch/x86_64/kernel/mce_amd.c b/arch/x86_64/kernel/mce_amd.c
index 1f76175..0b62a44 100644
--- a/arch/x86_64/kernel/mce_amd.c
+++ b/arch/x86_64/kernel/mce_amd.c
@@ -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 @@
 	struct mce m;
 
 	ack_APIC_irq();
+	exit_idle();
 	irq_enter();
 
 	memset(&m, 0, sizeof(m));
diff --git a/arch/x86_64/kernel/mce_intel.c b/arch/x86_64/kernel/mce_intel.c
index 0be0a79..3ef845e 100644
--- a/arch/x86_64/kernel/mce_intel.c
+++ b/arch/x86_64/kernel/mce_intel.c
@@ -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 @@
 
 	ack_APIC_irq();
 
+	exit_idle();
 	irq_enter();
 	if (time_before(jiffies, __get_cpu_var(next_check)))
 		goto done;
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index c9df991..669cf0e 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -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 @@
 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 @@
 				idle = default_idle;
 			if (cpu_is_offline(smp_processor_id()))
 				play_dead();
+			enter_idle();
 			idle();
+			__exit_idle();
 		}
 
 		preempt_enable_no_resched();
diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index cfc3d9d..6a666d2 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -27,6 +27,7 @@
 #include <asm/mmu_context.h>
 #include <asm/proto.h>
 #include <asm/apicdef.h>
+#include <asm/idle.h>
 
 /*
  *	Smarter SMP flushing macros. 
@@ -512,6 +513,7 @@
 	/*
 	 * At this point the info structure may be out of scope unless wait==1
 	 */
+	exit_idle();
 	irq_enter();
 	(*func)(info);
 	irq_exit();