[Intel-gfx] [PATCH 07/31] drm/i915/execlists: Direct submission of new requests (avoid tasklet/ksoftirqd)

[Tvrtko Ursulin]

On 28/06/2018 13:11, Chris Wilson wrote:
> Quoting Chris Wilson (2018-06-28 13:07:51)
>> Quoting Tvrtko Ursulin (2018-06-28 12:56:56)
>>> And tasklet kick from intel_enable_engine_stats, hm yep. But wouldn't
>>> taking the timeline lock around active state reconstruction solve that
>>> simpler?
>>
>> Can you? We probably can. (That one was a very recent discovery and
>> quick fix.)
> 
> The biggest issue being whether or not the same locking applies equally
> to all submission backends. That's not yet true, but then again we don't
> use stats everywhere. So whether or not that's an issue, I don't know,
> but it's enough to make me want to punt changing the locking inside
> intel_enable_engine_stats to a separate patch.

Big benefit is removing the extra tasklet schedule from engine stats 
which is in fact even racy. We need the state reconstruction to be 
atomic so I think it really needs to be under the engine lock.

tasklet_disable/enable can then also be dropped I think.

To which patch in this series that belongs is the question. Last one I 
think, when all is in place that port updates are protected by the 
timeline lock.

Regards,

Tvrtko