[Intel-gfx] [PATCH] drm/i915: Use discardable buffers for rings

[Joonas Lahtinen]

On to, 2017-04-20 at 11:17 +0100, Chris Wilson wrote:
> The contents of a ring are only valid between HEAD and TAIL, when the
> ring is idle (HEAD == TAIL) we can simply let the pages go under memory
> pressue if they are not pinned by an active context. And new content
> will be written and so the ring will again be valid between HEAD and
> TAIL, everything outside can be discarded.
> 
> Note that we take care of ensuring that we do not reset the HEAD
> backwards following a GPU hang on an idle ring.
> 
> The same precautions are what enable us to use stolen memory for rings.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation