Andi Kleen wrote:

Do you have some lmbench numbers before/after this change? 
iirc at least fork and exit do a lot of pte accesses in various forms.
If it's measurable it might be needed to patch those for the native case.
  

I don't.  I think Rusty ran some numbers and found the pte accessors
became the most commonly used paravirt ops.

I'm working on revamping the pv_ops patching infrastructure at the
moment, so we should be able to deal with these fairly efficiently.

    J