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[Xen-devel] Re: [PATCH] xen: core dom0 support

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] xen: core dom0 support
From: Anthony Liguori <anthony@xxxxxxxxxxxxx>
Date: Wed, 04 Mar 2009 11:34:04 -0600
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
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Jeremy Fitzhardinge wrote:
Nick Piggin wrote:

It really depends on the workload. There's three cases to consider: software shadow pagetables, hardware nested pagetables, and Xen direct pagetables. Even now, Xen's (highly optimised) shadow pagetable code generally out-performs modern nested pagetables, at least when running Windows (for which that code was most heavily tuned).

Can you point to benchmarks?  I have a hard time believing this.

How can shadow paging beat nested paging assuming the presence of large pages?


Anthony Liguori

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