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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>
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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 :-)

Thanks,

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




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