From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: The HPET issue on Linux
Date: Thu, 7 Jan 2010 08:45:28 +0200
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Cc: Beth Kon <eak@us.ibm.com>, dlaor@redhat.com,
	Sheng Yang <sheng@linux.intel.com>, kvm@vger.kernel.org
To: Anthony Liguori <anthony@codemonkey.ws>
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On Wed, Jan 06, 2010 at 04:42:30PM -0600, Anthony Liguori wrote:
> On 01/06/2010 02:37 PM, Gleb Natapov wrote:
> >We have exactly that hook in apic already and that's how RTC determines
> >that interrupt was coalesced.
> 
> AFAICT, apic_irq_delivered is only reset explicitly by the RTC when
> the line is lowered.  It's not currently lowered based on EOI.
> 
Correct. We can expose ACK notifiers to userspace (and if we want to
move assigned devices into userspace we have to), but I'd rather avoid
it.

> How can this mechanism be used with the HPET when operating in edge
> triggered mode?
>
If interrupt is coalesced increment counter and double HPET timer
frequency. When counter is zeroed return HPET timer to normal frequency.

--
			Gleb.