On Fri, Aug 09, 2013 at 12:26:45PM +0100, Chris Wilson wrote: > As mentioned in the previous commit, reads and writes from both the CPU > and GPU go through the LLC. This gives us coherency between the CPU and > GPU irrespective of the attribute settings either device sets. We can > use to avoid having to clflush even uncached memory. > > Except for the scanout. > > The scanout resides within another functional block that does not use > the LLC but reads directly from main memory. So in order to maintain > coherency with the scanout, writes to uncached memory must be flushed. > In order to optimize writes elsewhere, we start tracking whether an > framebuffer is attached to an object. > > v2: Use pin_display tracking rather than fb_count (to ensure we flush > cursors as well etc) and only force the clflush along explicit writes to > the scanout paths (i.e. pin_to_display_plane and pwrite into scanout). > > v3: Force the flush after hitting the slowpath in pwrite, as after > dropping the lock the object's cache domain may be invalidated. (Ville) > > Based on a patch by Ville Syrjälä. > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
