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Re: [patch V2 05/10] timer: Retrieve next expiry of pinned/non-pinned timers seperately

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From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [patch V2 05/10] timer: Retrieve next expiry of pinned/non-pinned timers seperately
Date Wed, 19 Apr 2017 09:10:01 +0200
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On Tue, Apr 18, 2017 at 01:11:07PM +0200, Thomas Gleixner wrote:
> --- a/kernel/time/timer.c
> +++ b/kernel/time/timer.c
> @@ -1472,23 +1472,27 @@ static u64 cmp_next_hrtimer_event(u64 ba
>   * get_next_timer_interrupt - return the time (clock mono) of the next timer
>   * @basej:	base time jiffies
>   * @basem:	base time clock monotonic
> + * @global_evt:	Pointer to store the expiry time of the next global timer
>   *
>   * Returns the tick aligned clock monotonic time of the next pending
>   * timer or KTIME_MAX if no timer is pending.
>   */
> -u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
> +u64 get_next_timer_interrupt(unsigned long basej, u64 basem, u64 *global_evt)

Another tortured function signature. It seems entirely possible
@global_evt will be the next.


> +
> +	/*
> +	 * If the local queue expires first, there is no requirement for
> +	 * queuing the CPU in the global expiry mechanism.

The comment doesn't make sense... (maybe at this stage)

> +	 */
> +	if (!local_first && !global_empty)
> +		*global_evt = basem + (nextevt_global - basej) * TICK_NSEC;

I was initially thinking !local_first would have to imply !global_empty,
but after going back and reading the previous patches again, I found
this was not so. Still slightly surprising.

> +
> +	return cmp_next_hrtimer_event(basem, local_evt);
>  }
>  
>  /**
> 
>

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[patch V2 00/10] timer: Move from a push remote at enqueue to a pull  at expiry model Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  [patch V2 06/10] timer: Restructure internal locking Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
    Re: [patch V2 06/10] timer: Restructure internal locking Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:10 +0200
  [patch V2 10/10] timer: Always queue timers on the local CPU Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  [patch V2 07/10] tick/sched: Split out jiffies update helper function Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:30 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:30 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:40 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:40 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 10:20 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 10:40 +0200
        Re: [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 11:10 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 10:40 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:00 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:10 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:50 +0200
        Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 12:00 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 11:50 +0200
        Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 12:00 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:30 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 12:30 +0200
  [patch V2 05/10] timer: Retrieve next expiry of pinned/non-pinned  timers seperately Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
    Re: [patch V2 05/10] timer: Retrieve next expiry of  pinned/non-pinned timers seperately Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:10 +0200
      Re: [patch V2 05/10] timer: Retrieve next expiry of pinned/non-pinned  timers seperately Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 12:00 +0200
  [patch V2 04/10] timer: Keep the pinned timers separate from the  others Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  Re: [patch V2 00/10] timer: Move from a push remote at enqueue to a  pull at expiry model "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-21 21:30 +0200

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