Re: [PATCH] KVM: SVM: Pass through the host kernel's IO delay port

[Gleb Natapov <gleb@redhat.com>]

On Mon, Jun 22, 2009 at 12:11:59PM +0200, Paolo Bonzini wrote:
> Avi Kivity wrote:
>> On 06/19/2009 01:15 PM, Paolo Bonzini wrote:
>>> From: Paolo Bonzini<pbonzini@redhat.com>
>>>
>>> KVM's optimization of guest port 80 accesses was removed last May 11
>>> in commit 99f85a.  However, this probably has speed penalties.  I don't
>>> have a machine to test but the equivalent VMX patch (fdef3ad) reported
>>> a speedup of 3-5%, and on the Xen mailing list it was mentioned that on
>>> Xen passing port 80 through had positive effects on startup speed.
>>>
>>> We can enable passthrough to the same port the host kernel uses instead.
>>
>> Since we don't tell the guest to use 0xed, this won't help.
>
> Won't the guest do that automatically through DMI?
>
DMI that guest sees is very different from DMI of the host.
What table is used to tell which port to use for io delay?

--
			Gleb.