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

From Daniel Lezcano <daniel.lezcano@linaro.org>
Newsgroups linux.kernel
Subject Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings
Date 2016-01-21 13:40 +0100
Message-ID <qTmGS-5g3-17@gated-at.bofh.it> (permalink)
References (1 earlier) <qT3uz-vq-41@gated-at.bofh.it> <qT6iK-2se-3@gated-at.bofh.it> <qT759-2KF-25@gated-at.bofh.it> <qTkc1-3tc-1@gated-at.bofh.it> <qTklH-3M2-1@gated-at.bofh.it>
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On 01/21/2016 11:08 AM, Peter Zijlstra wrote:
> On Thu, Jan 21, 2016 at 10:50:27AM +0100, Daniel Lezcano wrote:
>
>> Actually, the handle passes dev_id in order to let the irqtimings to sort
>> out a shared interrupt and prevent double sampling. In other words, for
>> shared interrupts, statistics should be per t-uple(irq , dev_id) but that is
>> something I did not implemented ATM.
>>
>> IMO, the handler is at the right place. The prediction code does not take
>> care of the shared interrupts yet.
>
> That certainly added to the confusion. But if you want per dev_id stats,
> the whole alloc framework is 'broken' too, for it allocates the stuff
> per irq.

Yep, that's correct. I was planning to re-work it later by handling the 
shared interrupts, assuming they were not so common, but regarding the 
examples below, that's wrong.

>> I tried to find a platform with shared interrupts in the ones I have
>> available around me but I did not find any. Are the shared interrupts
>> something used nowadays or coming from legacy hardware ? What is the
>> priority to handle the shared interrupts in the prediction code ?
>
> They're less common (thankfully) than they used to be, but I still have
> them:
>
> root@ivb-ep:~# cat /proc/interrupts | grep ","
>    59:          0          0          0          0          0          0
>    0          0          0          0          0          0          0
>    0          0          0          0          0          0          0
>    0          0          0          0          0          0          0
>    0          0          0          0          0          0          0
>    0          0          0          0          0          0   IO-APIC
>    5-fasteoi   i801_smbus, i801_smbus
>
> root@wsm-ep:~# cat /proc/interrupts | grep ","
>   18:          0          0          0          0          0          0          0          0          0          0          0          0   IO-APIC  18-fasteoi   ehci_hcd:usb1, uhci_hcd:usb6
>   19:    9695230   19577242   13205011    3970578     740376    1138693          0          0          0          0          0          0   IO-APIC  19-fasteoi   uhci_hcd:usb5, ata_piix
>   23:          3          0          0          0        927          0          0          0          0          0          0          0   IO-APIC  23-fasteoi   ehci_hcd:usb2, uhci_hcd:usb4
>
> root@snb:~# cat /proc/interrupts | grep ","
>   19:   11058485          0          0          0          0          0          0          0   IO-APIC  19-fasteoi   ata_piix, ata_piix
>
>
> Also there's a whole host of SOCs that has them.

Ah, I see. Thank you very much for these examples.

Sounds like, I have to handle the shared interrupts sooner than what I 
was expecting ... :)

   -- Daniel



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Thread

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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