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Re: [Xen-devel] irq_guest_eoi_timer interaction with MSI

  • To: Jan Beulich <jbeulich@xxxxxxxxxx>
  • From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • Date: Thu, 13 Nov 2008 16:22:54 +0000
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 13 Nov 2008 08:23:19 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AclFq+KWINmAHrGfEd2N7wAX8io7RQAADISJ
  • Thread-topic: [Xen-devel] irq_guest_eoi_timer interaction with MSI

On 13/11/08 16:21, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:

>> 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.

Also I'll add we currently do a hypercall for every level-triggered IO-APIC
IRQ, which was really all we supported until recently. Seemed to work well
enough performance-wise in that case.

 -- Keir

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