[Intel-gfx] [PATCH 09/33] drm/i915: Mark unmappable GGTT entries as PIN_HIGH

[Chris Wilson]

On Tue, Aug 09, 2016 at 12:05:30PM +0100, Tvrtko Ursulin wrote:
> 
> On 07/08/16 15:45, Chris Wilson wrote:
> >We allocate a few objects into the GGTT that we never need to access via
> >the mappable aperture (such as contexts, status pages). We can request
> >that these are bound high in the VM to increase the amount of mappable
> >aperture available. However, anything that may be frequently pinned
> >(such as logical contexts) we want to use the fast search & insert.
> 
> Is the last bit still true after you merged:
> 
>   commit 202b52b7fbf70858609ec20829c7d69a13ffa351
>   Author: Chris Wilson <chris at chris-wilson.co.uk>
>   Date:   Wed Aug 3 16:04:09 2016 +0100
> 
>       drm: Track drm_mm nodes with an interval tree
> 
> Or we could PIN_HIGH the LRCs as well now?

It is still true. I've another set of patches for drm_mm to speed up the
actual PIN_HIGH searching, but that is still slower than using the
eviction stack. It's a tradeoff of causing fragmentation (and maybe
hitting a slow cleanup path) or faster allocation when creating
contexts. I think the tradeoff is still towards causing fragmentation.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre