[Intel-gfx] [RFC PATCH 00/15] drm/i915: initial support for huge gtt pages

[Chris Wilson]

On Mon, Mar 06, 2017 at 11:53:59PM +0000, Matthew Auld wrote:
> This series adds support for huge-pages for the gtt, where "huge"
> is 64K, 2M and 1G. This isn't everything I have and there are still some
> things which I have yet to implement, like handling evict-for-node with the
> 64K/4K trickiness, but the hope here is to get some early feedback if possible.
> 
> One open question I still have is how the page-size should be handled at the
> gem object level, should the page-size be an implementation detail of whichever
> backend the gem object uses, where the selected page-size would solely depend
> on the size of the object and the availability of huge pages, or do we intend
> to expose some kind of hinting, both within our driver and possibly to
> userspace?

I thought the intention was to use optimistic superpages in the GTT (and
so optimistic large allocations).

One question I have is how do you mix swiotlb limits? We currently have
a trial-and-error approach to whittle down the sg chunks, which prevents
having a predetermined pagesize (at least as far as the GTT is
concerned).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre