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/include/linux/tick.h b/include/linux/tick.h
index 0fadf95d..a881c65 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -39,6 +39,8 @@
  * @idle_calls:		Total number of idle calls
  * @idle_sleeps:	Number of idle calls, where the sched tick was stopped
  * @idle_entrytime:	Time when the idle call was entered
+ * @idle_waketime:	Time when the idle was interrupted
+ * @idle_exittime:	Time when the idle state was left
  * @idle_sleeptime:	Sum of the time slept in idle with sched tick stopped
  * @sleep_length:	Duration of the current idle sleep
  */
@@ -53,6 +55,8 @@
 	unsigned long			idle_sleeps;
 	int				idle_active;
 	ktime_t				idle_entrytime;
+	ktime_t				idle_waketime;
+	ktime_t				idle_exittime;
 	ktime_t				idle_sleeptime;
 	ktime_t				idle_lastupdate;
 	ktime_t				sleep_length;