[Intel-gfx] [PATCH 61/66] drm/i915: Use multiple VMs

[Ville Syrjälä]

On Tue, Jul 02, 2013 at 12:07:10PM +0100, Chris Wilson wrote:
> On Tue, Jul 02, 2013 at 01:58:13PM +0300, Ville Syrjälä wrote:
> > Also IIRC someone told me that w/ uncached mappings the caches aren't
> > snooped even on LLC platforms. If that's true, MOCS seems even more
> > dangerous since the client could easily mix cached and uncached
> > accesses. I don't really understand why uncached mappings wouldn't
> > snoop on LLC platforms since the snooping should be more or less free.
> 
> Who said that? Doesn't appear to be the case on SNB/IVB/HSW as far as I
> can tell.

Can't remember now who said it, or could be I just misunderstood. But if
it's not true, then MOCS seems actually useful. Otherwise it's going to
be a clflush fest when you want to change from cached to uncached.

-- 
Ville Syrjälä
Intel OTC