[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/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);