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[PATCH 6/9] sched/clock: Remove watchdog touching

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  [PATCH 6/9] sched/clock: Remove watchdog touching Peter Zijlstra <peterz@infradead.org> - 2017-04-21 19:50 +0200
    Re: [PATCH 6/9] sched/clock: Remove watchdog touching Peter Zijlstra <peterz@infradead.org> - 2017-04-21 19:50 +0200

#1628394 — [PATCH 6/9] sched/clock: Remove watchdog touching

Commit:

  2bacec8c318c ("sched: touch softlockup watchdog after idling")

introduced the touch_softlockup_watchdog_sched() call without
justification and I feel sched_clock management is not the right
place, it should only be concerned with producing semi coherent time.

If this causes watchdog thingies, we can find a better place.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/clock.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -410,15 +410,21 @@ void sched_clock_idle_sleep_event(void)
 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
 
 /*
- * We just idled; resync with ktime. (called with irqs disabled):
+ * We just idled; resync with ktime.
  */
 void sched_clock_idle_wakeup_event(void)
 {
-	if (timekeeping_suspended)
+	unsigned long flags;
+
+	if (sched_clock_stable())
+		return;
+
+	if (unlikely(timekeeping_suspended))
 		return;
 
+	local_irq_save(flags);
 	sched_clock_tick();
-	touch_softlockup_watchdog_sched();
+	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
 

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#1628397

On Fri, Apr 21, 2017 at 04:58:02PM +0200, Peter Zijlstra wrote:
> Commit:
> 
>   2bacec8c318c ("sched: touch softlockup watchdog after idling")
> 
> introduced the touch_softlockup_watchdog_sched() call without
> justification and I feel sched_clock management is not the right
> place, it should only be concerned with producing semi coherent time.
> 
> If this causes watchdog thingies, we can find a better place.

Hurmph, the rest should've gone in the next patch, which calls
sched_clock_idle_wakeup_event() from a place with IRQs enabled.

> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>  kernel/sched/clock.c |   12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> --- a/kernel/sched/clock.c
> +++ b/kernel/sched/clock.c
> @@ -410,15 +410,21 @@ void sched_clock_idle_sleep_event(void)
>  EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
>  
>  /*
> - * We just idled; resync with ktime. (called with irqs disabled):
> + * We just idled; resync with ktime.
>   */
>  void sched_clock_idle_wakeup_event(void)
>  {
> -	if (timekeeping_suspended)
> +	unsigned long flags;
> +
> +	if (sched_clock_stable())
> +		return;
> +
> +	if (unlikely(timekeeping_suspended))
>  		return;
>  
> +	local_irq_save(flags);
>  	sched_clock_tick();
> -	touch_softlockup_watchdog_sched();
> +	local_irq_restore(flags);
>  }
>  EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
>  
> 
> 

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