This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Essay on an important Xen decision (long)

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Essay on an important Xen decision (long)
From: Anthony Liguori <aliguori@xxxxxxxxxx>
Date: Wed, 11 Jan 2006 10:25:08 -0600
Cc: "Magenheimer, Dan \(HP Labs Fort Collins\)" <dan.magenheimer@xxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Wed, 11 Jan 2006 16:32:11 +0000
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <ca704ea5ca30b98dca4508cd6bfdf581@xxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <516F50407E01324991DD6D07B0531AD59030F8@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <43C41133.3050606@xxxxxxxxxx> <ca704ea5ca30b98dca4508cd6bfdf581@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla Thunderbird 1.0.7 (X11/20051013)
Hi Keir,

Keir Fraser wrote:

On an architecture where VP is cheaper to implement than on x86, it may well make sense to do that in preference to P2M. As you say, it makes certain future extensions less of a pain to implement.

Is VP on x86 expensive in terms of performance or complexity?

I imagine that you would have to always have shadow paging enable but you could still do bulk updates ala writable page tables so the performance cost should be minimal I would think.

Trying to understand the memory system in more details so any additional info is much appreciate :-)


Anthony Liguori

If ia64 does decide to back off from the P==M route then I suspect VP is the way to go (which is I think how ia64 domU's currently work anyway).

 -- Keir

Xen-devel mailing list