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Commit 5df7fa1c authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 1001d0a9

include/linux/tick.h

+4 −0
Original line number Diff line number Diff line
@@ -39,6 +39,8 @@ enum tick_nohz_mode { 
 * @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 @@ struct tick_sched { 
	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;

kernel/time/tick-sched.c

+2 −0
Original line number Diff line number Diff line
@@ -137,6 +137,7 @@ void tick_nohz_update_jiffies(void) 


	cpu_clear(cpu, nohz_cpu_mask);

	now = ktime_get();

	ts->idle_waketime = now;



	local_irq_save(flags);

	tick_do_update_jiffies64(now);
@@ -400,6 +401,7 @@ void tick_nohz_restart_sched_tick(void) 
	 * Cancel the scheduled timer and restore the tick

	 */

	ts->tick_stopped  = 0;

	ts->idle_exittime = now;

	hrtimer_cancel(&ts->sched_timer);

	ts->sched_timer.expires = ts->idle_tick;

kernel/time/timer_list.c

+2 −0
Original line number Diff line number Diff line
@@ -166,6 +166,8 @@ static void print_cpu(struct seq_file *m, int cpu, u64 now) 
		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);