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Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings
Date 2016-01-20 20:10 +0100
Message-ID <qT6iK-2se-3@gated-at.bofh.it> (permalink)
References <qT3ux-vq-3@gated-at.bofh.it> <qT3uz-vq-41@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, Jan 20, 2016 at 05:00:32PM +0100, Daniel Lezcano wrote:
> +++ b/kernel/irq/handle.c
> @@ -165,6 +165,7 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
>  			/* Fall through to add to randomness */
>  		case IRQ_HANDLED:
>  			flags |= action->flags;
> +			handle_irqtiming(irq, action->dev_id);
>  			break;
>  
>  		default:

> +++ b/kernel/irq/internals.h

> +static inline void handle_irqtiming(unsigned int irq, void *dev_id)
> +{
> +	if (__irqtimings->handler)
> +		__irqtimings->handler(irq, ktime_get(), dev_id);
> +}

Here too, ktime_get() is daft.

Also, you really want to take the timestamp _before_ we call the
handlers, not after, otherwise you mix in whatever variance exist in the
handler duration.

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Re: [RFC PATCH 2/2] sched: idle: IRQ based next prediction for idle  period Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-18 14:30 +0100
  Re: [RFC PATCH 2/2] sched: idle: IRQ based next prediction for idle  period Thomas Gleixner <tglx@linutronix.de> - 2016-01-20 16:50 +0100
    [RFC V2 2/2] sched: idle: IRQ based next prediction for idle period Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-20 17:10 +0100
      Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-01-20 18:50 +0100
        Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Peter Zijlstra <peterz@infradead.org> - 2016-01-20 19:50 +0100
        Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 11:10 +0100
      Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Peter Zijlstra <peterz@infradead.org> - 2016-01-20 20:10 +0100
        Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-01-20 20:20 +0100
          Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Peter Zijlstra <peterz@infradead.org> - 2016-01-20 20:40 +0100
      Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Peter Zijlstra <peterz@infradead.org> - 2016-01-20 20:40 +0100
      Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Peter Zijlstra <peterz@infradead.org> - 2016-01-20 20:50 +0100
        Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-01-20 21:00 +0100
          Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Peter Zijlstra <peterz@infradead.org> - 2016-01-20 21:30 +0100
      Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Thomas Gleixner <tglx@linutronix.de> - 2016-01-20 21:00 +0100
        Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 15:00 +0100
          Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Thomas Gleixner <tglx@linutronix.de> - 2016-01-21 15:20 +0100
    [RFC V2 0/2] IRQ based next prediction Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-20 17:10 +0100
    [RFC V2 2/2] sched: idle: IRQ based next prediction for idle period Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-20 17:10 +0100
      Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-01-20 21:20 +0100
        Re: [RFC V2 2/2] sched: idle: IRQ based next prediction for idle  period Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 14:10 +0100
    [RFC V2 0/2] IRQ based next prediction Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-20 17:10 +0100
      [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-20 17:10 +0100
        Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-20 19:00 +0100
          Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 10:30 +0100
            Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-21 11:30 +0100
        Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Peter Zijlstra <peterz@infradead.org> - 2016-01-20 20:10 +0100
          Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-20 21:00 +0100
            Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-01-20 21:10 +0100
            Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Peter Zijlstra <peterz@infradead.org> - 2016-01-20 21:30 +0100
              Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-20 21:30 +0100
            Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 11:00 +0100
              Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Peter Zijlstra <peterz@infradead.org> - 2016-01-21 11:10 +0100
                Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 13:40 +0100
                Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-21 21:30 +0100
              Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-21 15:00 +0100
                Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 15:20 +0100
                Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Thomas Gleixner <tglx@linutronix.de> - 2016-01-21 20:00 +0100
                Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Peter Zijlstra <peterz@infradead.org> - 2016-01-22 11:20 +0100
          Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 10:30 +0100
        Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Peter Zijlstra <peterz@infradead.org> - 2016-01-20 20:30 +0100
          Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-21 11:00 +0100
      [RFC V2 1/2] irq: Add a framework to measure interrupt timings Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-01-20 17:10 +0100

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