[Intel-gfx] [PATCH 06/11] drm/i915: Allocate active tracking nodes from a slabcache

[Chris Wilson]

Quoting Chris Wilson (2019-01-30 16:08:59)
> Quoting Tvrtko Ursulin (2019-01-30 15:57:06)
> > Under what scenarios we end up not freeing active nodes sufficiently? It 
> > would have to be some user which keeps many contexts around, having only 
> > used them once?
> 
> Never in a typical scenario :) Almost every allocation is served from
> the last_request slot, you need to have a pair of concurrent references
> to a vma for it to activate, and that takes multiple engines reading the
> same object within a context/ppgtt.

That being said, that applies to vma. HW semaphores is an example where
the cacheline could be shared far and wide with uncertain lifetimes.
Context barriers in contrast just have a few different timelines and
idle almost immediately.
-Chris