linux-kernel - Re: [tip: timers/core] hrtimer: Consolidate reprogramming code

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Message-ID: <bc6b74396cd6b5a4eb32ff90bcc1cb059216e0f3.camel@gmx.de>
Date:   Thu, 12 Aug 2021 17:04:02 +0200
From:   Mike Galbraith <efault@....de>
To:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        linux-tip-commits@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>, x86@...nel.org
Subject: Re: [tip: timers/core] hrtimer: Consolidate reprogramming code

On Thu, 2021-08-12 at 16:32 +0200, Thomas Gleixner wrote:
> 
> Can you please test whether the below fixes it for you?

Yes, that boots.

> I have yet to find a machine which reproduces it as I really want to
> understand which particular part is causing this.

Config attached just in case.

> Thanks,
> 
>         tglx
> ---
> --- a/kernel/time/hrtimer.c
> +++ b/kernel/time/hrtimer.c
> @@ -652,24 +652,10 @@ static inline int hrtimer_hres_active(vo
>         return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
>  }
>  
> -static void
> -__hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal,
> -                   struct hrtimer *next_timer, ktime_t expires_next)
> +static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
> +                               struct hrtimer *next_timer,
> +                               ktime_t expires_next)
>  {
> -       /*
> -        * If the hrtimer interrupt is running, then it will reevaluate
> the
> -        * clock bases and reprogram the clock event device.
> -        */
> -       if (cpu_base->in_hrtirq)
> -               return;
> -
> -       if (expires_next > cpu_base->expires_next)
> -               return;
> -
> -       if (skip_equal && expires_next == cpu_base->expires_next)
> -               return;
> -
> -       cpu_base->next_timer = next_timer;
>         cpu_base->expires_next = expires_next;
>  
>         /*
> @@ -707,8 +693,10 @@ hrtimer_force_reprogram(struct hrtimer_c
>  
>         expires_next = hrtimer_update_next_event(cpu_base);
>  
> -       __hrtimer_reprogram(cpu_base, skip_equal, cpu_base->next_timer,
> -                           expires_next);
> +       if (skip_equal && expires_next == cpu_base->expires_next)
> +               return;
> +
> +       __hrtimer_reprogram(cpu_base, cpu_base->next_timer,
> expires_next);
>  }
>  
>  /* High resolution timer related functions */
> @@ -863,7 +851,19 @@ static void hrtimer_reprogram(struct hrt
>         if (base->cpu_base != cpu_base)
>                 return;
>  
> -       __hrtimer_reprogram(cpu_base, true, timer, expires);
> +       if (expires >= cpu_base->expires_next)
> +               return;
> +
> +       /*
> +        * If the hrtimer interrupt is running, then it will reevaluate
> the
> +        * clock bases and reprogram the clock event device.
> +        */
> +       if (cpu_base->in_hrtirq)
> +               return;
> +
> +       cpu_base->next_timer = timer;
> +
> +       __hrtimer_reprogram(cpu_base, timer, expires);
>  }
>  
>  static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,


Download attachment "config.gz" of type "application/gzip" (39362 bytes)