[Intel-gfx] [PATCH v2 06/11] drm/i915/scheduler: Record all dependencies upon request construction

[Chris Wilson]

On Thu, Nov 10, 2016 at 10:44:44AM +0000, Tvrtko Ursulin wrote:
> 
> On 08/11/2016 12:20, Chris Wilson wrote:
> >On Mon, Nov 07, 2016 at 01:59:45PM +0000, Chris Wilson wrote:
> >>The scheduler needs to know the dependencies of each request for the
> >>lifetime of the request, as it may choose to reschedule the requests at
> >>any time and must ensure the dependency tree is not broken. This is in
> >>additional to using the fence to only allow execution after all
> >>dependencies have been completed.
> >>
> >>One option was to extend the fence to support the bidirectional
> >>dependency tracking required by the scheduler. However the mismatch in
> >>lifetimes between the submit fence and the request essentially meant
> >>that we had to build a completely separate struct (and we could not
> >>simply reuse the existing waitqueue in the fence for one half of the
> >>dependency tracking). The extra dependency tracking simply did not mesh
> >>well with the fence, and keeping it separate both keeps the fence
> >>implementation simpler and allows us to extend the dependency tracking
> >>into a priority tree (whilst maintaining support for reordering the
> >>tree).
> >>
> >>To avoid the additional allocations and list manipulations, the use of
> >>the priotree is disabled when there are no schedulers to use it.
> >>
> >>v2: Create a dedicated slab for i915_dependency.
> >>    Rename the lists.
> >
> >Sod. I've squashed the priority sort into this as a rebase calamity.
> 
> Waiting for the other patches to get looked at before
> untangle/respin or just forgot? :)

Just imagine the split ;) Think of the intel_lrc.c as a separate patch.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre