xen-users
Re: [Xen-users] Re: [Xen-devel] VMX Hardware
On 14 Aug 2005, at 19:09, Anthony Liguori wrote:
The Pacifica spec does mention optional hardware support for "Nested
Page Tables" which is essentially hardware shadow page tables.
Should be interesting to see the performance difference between
software/hardware shadow page tables.
I have doubts about the performance of hardware page tables, unless
there's a clever TLB design. A pagetable walk which is four memory
accesses on normal x86/64 becomes twenty accesses in nested mode!
It may be that shadow pagetables, by providing a bigger 'cache' for
guest->host mappings, can actually perform better on many workloads.
I guess we'll see -- if silicon is produced that supports that mode,
someone is bound to add support to Xen.
-- Keir
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