tick-sched: add more debug information

To allow better diagnosis of tick-sched related, especially NOHZ
related problems, we need to know when the last wakeup via an irq
happened and when the CPU left the idle state.

Add two fields (idle_waketime, idle_exittime) to the tick_sched
structure and add them to the timer_list output.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 12c5f4c..d3d94c1 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -166,6 +166,8 @@
 		P(idle_calls);
 		P(idle_sleeps);
 		P_ns(idle_entrytime);
+		P_ns(idle_waketime);
+		P_ns(idle_exittime);
 		P_ns(idle_sleeptime);
 		P(last_jiffies);
 		P(next_jiffies);