Messages in this thread | | | Date | Thu, 31 May 2012 18:41:54 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: Make kstat_incr_irqs_this_cpu() called when an irq is actually being handled |
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On Thu, 31 May 2012, Ning Jiang wrote: > kstat_incr_irqs_this_cpu() is supposed to record the irq number > that is actually taken by a certain cpu. But it failed to do so > in its current form.
It exactly counts the number of interrupts which are delivered to and handled by a CPU. That includes interrupts which are delivered in a state where the device handler cannot be called. And this is on purpose. We want to see the real number of interruptions not the number of calls to a device handler.
> For level irq, if its disabled or no action available, we'll skip > irq handling. When it is enabled later, the irq will be retriggered > and kstat_incr_irqs_this_cpu() will be counted twice for this > single irq.
This counts the number of interrupts arrived at the CPU and therefor it counts TWO in this situation. The CPU is interrupted twice, not once.
Thanks,
tglx
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