[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: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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);