[Intel-gfx] [PATCH v3] drm/i915/execlists: Set queue priority from secondary port

[Tvrtko Ursulin]

On 11/04/2018 12:34, Chris Wilson wrote:
> Quoting Chris Wilson (2018-04-11 11:39:29)
>> We can refine our current execlists->queue_priority if we inspect
>> ELSP[1] rather than the head of the unsubmitted queue. Currently, we use
>> the unsubmitted queue and say that if a subsequent request is more
>> important than the current queue, we will rerun the submission tasklet
>> to evaluate the need for preemption. However, we only want to preempt if
>> we need to jump ahead of a currently executing request in ELSP. The
>> second reason for running the submission tasklet is amalgamate requests
>> into the active context on ELSP[0] to avoid a stall when ELSP[0] drains.
>> (Though repeatedly amalgamating requests into the active context and
>> triggering many lite-restore is off question gain, the goal really is to
>> put a context into ELSP[1] to cover the interrupt.) So if instead of
>> looking at the head of the queue, we look at the context in ELSP[1] we
>> can answer both of the questions more accurately -- we don't need to
>> rerun the submission tasklet unless our new request is important enough
>> to feed into, at least, ELSP[1].
>>
>> v2: Add some comments from the discussion with Tvrtko.
>> v3: More commentary to cross-reference queue_request()
>>
>> References: f6322eddaff7 ("drm/i915/preemption: Allow preemption between submission ports")
>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> Cc: Michał Winiarski <michal.winiarski at intel.com>
>> Cc: Michel Thierry <michel.thierry at intel.com>
>> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
>> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
>  From the discussion thread,
> 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> I assume Tvrtko is happy with the comments added based on that
> conversation.

Yes, all fine!

Regards,

Tvrtko