Re: Anonymoose ggtt_view_params

Chris Wilson
2017-01-13T11:11:17Z

On Fri, Jan 13, 2017 at 10:59:46AM +0000, Tvrtko Ursulin wrote:
>
> On 13/01/2017 10:33, Chris Wilson wrote:
> >Ok, ok, this cover note only exists to continue the run on joke of my
> >mispellings!
> >
> >Everything but
> >[5/7] drm/i915: Convert i915_ggtt_view to use an anonymous union
> >has a r-b, so this is a good time to complain if this is too much of a
> >hack.
>
> If you could polish your clouded crystal ball to see if more view
> types might be coming, which then might have a colliding parameters
> size and foil the whole idea.
>
> I do think it is a little bit of hack with a questionable benefit.
> And I think I asked a few times if you really see a performance
> difference for a few bytes smaller memcmp? Presumably it would be
> some test case with a huge number of partial views which could
> theoretically maybe show something?

It was the doubling code size of i915_vma_compare() that struck me as
objectionable.

> Downside is if we need to revert it would be relatively "churny".

We just split the type into two fields, the enum and size.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre