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RE: [Xen-devel] bogus HPET initialization order on x86

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: RE: [Xen-devel] bogus HPET initialization order on x86
From: "Wei, Gang" <gang.wei@xxxxxxxxx>
Date: Fri, 11 Mar 2011 17:49:52 +0800
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Cc: Keir Fraser <keir.xen@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Yu, Ke" <ke.yu@xxxxxxxxx>, "Wei, Gang" <gang.wei@xxxxxxxxx>
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Thread-topic: [Xen-devel] bogus HPET initialization order on x86
Jan Beulich wrote on 2011-03-11:
>>>> On 10.03.11 at 04:35, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote:
>> Jan Beulich wrote on 2011-03-09:
>>> Also, what's the point of decrementing the per-CPU irq_count in
>>> hpet_legacy_irq_tick()?
>> The per-CPU irq_count are used for calculate the total irq number
>> excluding hpet irqs in a past period to give a estimation of IO
>> frequence. The hpet irq was counted in do_IRQ, so need to reduce it
>> while handling it. You can see another one in hpet_interrupt_handler().
> I can understand the latter, but the one I was asking about decrements
> irq_count even if not calling the event handler (i.e.
> when returning zero from the function). In other words, I would have
> understood what this is for if it was sitting after the initial if().

The irq_count is added to count the total irq number excluding hpet/pit irqs, 
so even the real event handler was not called, the adjustment should still be 


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