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Re: [Xen-devel] irq_guest_eoi_timer interaction with MSI

To: Jan Beulich <jbeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] irq_guest_eoi_timer interaction with MSI
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Thu, 13 Nov 2008 16:21:30 +0000
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On 13/11/08 15:28, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

>> PHYSDEVOP_eoi and unmask happen at the same time for pirqs. The fact that we
>> only need this new mechanism for pirqs, and that we already have a gated
>> hypercall for pirq eoi (and can gate it further if need be) is an argument
>> for hanging this off PHYSDEVOP_eoi imo.
> 
> But then there'd be a hypercall for each MSI instance, most of the time
> without any real need. With a high interrupt rate I'm afraid this does
> matter.

I don't understand what you mean. There is a one-to-one-one relationship
between MSIs, PIRQs, and event channels.

 -- Keir



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