[Intel-gfx] [PATCH v2] drm/i915: Priority boost for new clients

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-08-07 10:08:28)
> 
> On 07/08/2018 08:29, Chris Wilson wrote:
> > +     /*
> > +      * The active request is now effectively the start of a new client
> > +      * stream, so give it the equivalent small priority bump to prevent
> > +      * it being gazumped a second time by another peer.
> > +      */
> > +     if (!(prio & I915_PRIORITY_NEWCLIENT)) {
> > +             list_move_tail(&active->sched.link,
> > +                            lookup_priolist(engine,
> > +                                            prio | I915_PRIORITY_NEWCLIENT));
> >       }
> >   }
> >   
> > 
> 
> This sounds fair, I think I'm okay with it. Does it still work well for 
> mixed media workloads?

Grr. Current drm-tip is scoring much much higher in fairness than I
remember, and there's no apparent improvement, even little room for
possible improvement. When in doubt, blame ksoftirqd ;)

Quite surprising though, it was (at least if memory serves) a dramatic
improvement from this patch. Time to see if the metrics do resemble what
I think they should be, and to see if I can find a good example in
media-bench.pl
-Chris