[Intel-gfx] [PATCH i-g-t 01/10] gem_wsim: Rip out userspace balancing

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-06-18 11:03:11)
> 
> On 18/06/2020 08:55, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2020-06-18 08:40:25)
> >>
> >> On 18/06/2020 08:14, Chris Wilson wrote:
> >>> Quoting Tvrtko Ursulin (2020-06-17 17:01:11)
> >>>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>>>
> >>>> Evaluation of userspace load balancing options was how this tool started
> >>>> but since we have settled on doing it in the kernel.
> >>>>
> >>>> Tomorrow we will want to update the tool for new engine interfaces and all
> >>>> this legacy code will just be a distraction.
> >>>>
> >>>> Rip out everything not related to explicit load balancing implemented via
> >>>> context engine maps and adjust the workloads to use it.
> >>>
> >>> Hmm, if this is on the table, should we also then restrict
> >>> load-balancing wsim to gen11+ so that we can use the timed loops rather
> >>> nop batches? That would be a huge selling point, and I'll just keep an
> >>> old checkout around for nop load balancing with all the trimmings.
> >>
> >> That was my plan for the next step yes. Just taking your patch without
> >> further changes would already make it work I think. But also at some
> >> point I want to convert the engine selection (and engine naming in
> >> descriptors) to class:instance.
> >>
> >> Why do you need the nop/old balancing stuff? I would hope going forward
> >> we only need to compare current balancing against any changes. So I'd
> >> really like to remoev the userspace balancing stuff.
> > 
> > There are still some cases where i915 is beaten by plain old contexts,
> > usually that is a combination of semaphores and interrupt latency, but
> > some I just don't understand. There is still an uncomfortably large
> > variation between kernel releases, and comparing the regressions in
> > different balancers is useful to narrow down the problem.
> 
> You could create separate workloads to simulate "-b context" to a 
> degree? I really want to rip this out. Can you cut your losses and 
> forget it existed? :)

It's fine; I can keep a stable benchmark around of a known checkout.
-Chris