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

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

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? :)

Regards,

Tvrtko

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