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

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

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@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? :)

Regards,

Tvrtko


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