Benjamin Herrenschmidt wrote:

On Wed, 2008-06-18 at 17:24 -0700, Linus Torvalds wrote:
  

quoted

On Wed, 18 Jun 2008, Jeremy Fitzhardinge wrote:
    

quoted

Along the lines of:
      

Hell no. There's a reason we have a special set_wrprotect() thing. We can 
do it more efficiently on native hardware by just clearing the bit 
atomically. No need to do the cmpxchg games.
    

But we can't batch ... 
  

Which architecture are you interested in?  If it isn't x86, you can 
probably get anything past Linus ;)

I'll do some measurements to see what effect the batchable 
ptep_set_wrprotect() has on native.  If it's significant, I'll propose 
making it conditional on CONFIG_PARAVIRT.

    J