[Intel-gfx] [PATCH] drm/i915/execlists: Remove the priority "optimisation"

[Chris Wilson]

Quoting Michał Winiarski (2017-10-24 13:26:59)
> On Tue, Oct 24, 2017 at 12:55:01PM +0100, Chris Wilson wrote:
> > Originally we set the priority to max upon inserting the request into
> > the execlists queue (and removing it from the scheduler lists). We could
> > then use the prio==INT_MAX as a shortcut within execlists_schedule() to
> > detect the end of the dependency chain. Since commit 1f181225f8ec
> > ("drm/i915/execlists: Keep request->priority for its lifetime") this is
> > no longer true as we use the request completion as an indicator the
> > schedule dependency chain is complete instead. (This allows us to then
> > reschedule requests even when its context is in flight.) However, this
> > makes the GEM_BUG_ON() inside execlists_schedule() racy as we may change
> > the rq->prio at the same time. As the assertion is useful, let's keep
> > the assertion and remove the micro-optimisation.
> > 
> > Fixes: 1f181225f8ec ("drm/i915/execlists: Keep request->priority for its lifetime")
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Michał Winiarski <michal.winiarski at intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> 
> Reviewed-by: Michał Winiarski <michal.winiarski at intel.com>

And pushed, thanks for the poke.
-Chris