[PATCH] i386: add idle notifier

Add a notifier mechanism to the low level idle loop.  You can register a
callback function which gets invoked on entry and exit from the low level idle
loop.  The low level idle loop is defined as the polling loop, low-power call,
or the mwait instruction.  Interrupts processed by the idle thread are not
considered part of the low level loop.

The notifier can be used to measure precisely how much is spent in useless
execution (or low power mode).  The perfmon subsystem uses it to turn on/off
monitoring.

Signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
index 3201d421090a..5785d84103a6 100644
--- a/arch/i386/kernel/irq.c
+++ b/arch/i386/kernel/irq.c
@@ -19,6 +19,8 @@
 #include <linux/cpu.h>
 #include <linux/delay.h>
 
+#include <asm/idle.h>
+
 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
 EXPORT_PER_CPU_SYMBOL(irq_stat);
 
@@ -61,6 +63,7 @@ fastcall unsigned int do_IRQ(struct pt_regs *regs)
         union irq_ctx *curctx, *irqctx;
         u32 *isp;
 #endif
+        exit_idle();
 
         if (unlikely((unsigned)irq >= NR_IRQS)) {
                 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",