RE: [Xen-devel] Shadow Page Tables in Xen

[Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>]

> Have you actually measured this? I think that the major cause of page
> faults and VM slowdown is -- rather than page faults on write access
> -- the fact that we blow the shadow pagetables away everytime we clean
> the dirty bitmap, and this requires a long operation to remove from
> top to bottom all reference counts and reconstructing later the shadow
> pagetables on the next memory accesses.

Yep, ideally we'd just walking all the shadow leaf PTE's to just remove write 
access. I'd guess that this would be a much more worthwhile optimization than 
trying to 'pre-fetch' write faults.

Ian  

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