Re: [Xen-devel] [PATCH] turn off writable page tables

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 29 Jul 2006, at 00:10, Zachary Amsden wrote:

> > > For SMP, the enter / leave must happen under protection of the page 
> > > table
> > > locks for page tables which are being modified.
> > This should be in a comment in the code
> Most definitely agreed!  I think it deserves an entire paragraph 
> explaining how to use it properly.  But I wanted to get input from the 
> Xen folks to see if this can be useful for them in some way first.
It would allow set_pte() to switch between explicit queuing and 
'direct' writing. We moved away from the former a few years back as 
doing it everywhere made a mess of the generic Linux mm code and it was 
hard to reason whether our patches were correct. I guess doing it for 
the most important subset of mm routines is not so bad. It's a shame 
that, although many set_pte() call sites could determine statically 
whether or not they will batch, we'd end up with a dynamic run-time 
test everywhere (unless I'm mistaken) -- I wonder if that has a 
measurable cost?
 -- Keir


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