Re: [patch] my mmu notifiers

[Jack Steiner <steiner@sgi.com>]

On Wed, Feb 20, 2008 at 12:11:57AM +0100, Nick Piggin wrote:
> On Tue, Feb 19, 2008 at 02:58:51PM +0100, Andrea Arcangeli wrote:
> > On Tue, Feb 19, 2008 at 09:43:57AM +0100, Nick Piggin wrote:
> > > anything when changing the pte to be _more_ permissive, and I don't
> > 
> > Note that in my patch the invalidate_pages in mprotect can be
> > trivially switched to a mprotect_pages with proper params. This will
> > prevent page faults completely in the secondary MMU (there will only
> > be tlb misses after the tlb flush just like for the core linux pte),
> > and it'll allow all the secondary MMU pte blocks (512/1024 at time
> > with my PT lock design) to be updated to have proper permissions
> > matching the core linux pte.
> 
> Sorry, I realise I still didn't get this through my head yet (and also
> have not seen your patch recently). So I don't know exactly what you
> are doing...
> 
> But why does _anybody_ (why does Christoph's patches) need to invalidate
> when they are going to be more permissive? This should be done lazily by
> the driver, I would have thought.


Agree. Although for most real applications, the performance difference
is probably negligible.

--- jack