For the older chipsets, i.e. pre-i965, which have severe alignment
restrictions for tiled buffers we need to pessimistically assume that we
will waste the size of buffer to meet those alignment constraints.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
If the kernel immediately frees the backing store for a buffer when
marking it purgeable, then there is not point adding to the cache. Free
it immediately, instead.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>