[Intel-gfx] [PATCH v2 08/11] drm/i915/execlists: Keep request->priority for its lifetime

[Chris Wilson]

Quoting Michał Winiarski (2017-09-28 10:14:47)
> On Wed, Sep 27, 2017 at 04:44:37PM +0000, Chris Wilson wrote:
> > With preemption, we will want to "unsubmit" a request, taking it back
> > from the hw and returning it to the priority sorted execution list. In
> > order to know where to insert it into that list, we need to remember
> > its adjust priority (which may change even as it was being executed).
> 
> This has a (positive IMO) side effect that should be mentioned here.
> 
> Starting from:
> drm/i915/execlists: Unwind incomplete requests on resets
> 
> We were using the fact, that were overwriting the priority on submit to HW, to
> resubmit the same requests on GPU reset.
> Since now we keep track of the priority, we're going to 'resubmit' with correct
> priority, making reset another "preemption" point. A quicker and more reliable
> preemption! Although a bit sad for the requests that were "preempted" this way :)

Bah. I am not keen that reset acts as an accidental preemption point.
Hence why I kept the behaviour of resubmitting exactly was on the hw at
the time of reset to avoid the notion of preemption happening before we
were expecting any.
 
> Please, add the same behavior to GuC submission path.

Why?
-Chris