[Intel-gfx] [PATCH 1/6] RFCish: write only mappings (aka non-blocking)

[Chris Wilson]

On Tue, 20 Sep 2011 13:06:43 +0200, Daniel Vetter <daniel at ffwll.ch> wrote:
>   Now non-blocking cpu mmaps make very much sense on llc/snooped buffer
>   objects. So I think we actually need an ioctl to get obj->cache_level so
>   userspace can decide whether it should use non-blocking gtt mmaps or cpu
>   (non-blocking) cpu mmaps. We might as well go full-circle, make Chris
>   happy and merge the corresponding set_cache_level ioclt to enable
>   snooped buffers on machines with ilk-like coherency (i.e. that atom
>   thing I'm hearing about ...). But imo that's material for non-blocking
>   mmaps, step 2.

That's not enough to make me completely happy. I also have the use-case
of wanting to efficiently handle compositing with client allocated
memory i.e. persistent ShmPixmaps, where coherency either needs to be
transparent to the client or (worse) synchronicity imposed by the server.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre