[Xen-devel] Re: [PATCH 1 of 4] mm: add a ptep_modify_prot transaction abstraction

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Benjamin Herrenschmidt wrote:
> On Mon, 2008-06-16 at 04:30 -0700, Jeremy Fitzhardinge wrote:
>   
> > The only current user of this interface is mprotect
> >     
> Do you plan to use it with fork ultimately ?
>   
Good point, I'd overlooked that.  I guess that means using it in 
ptep_set_wrprotect().
At present the x86 ptep_set_wrprotect() just uses clear_bit on the pte, 
which is a locked cycle.  Is that significantly cheaper than an xchg + 
set?  (Same number of locked operations...)
   J

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel