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@xxxxxxxxxxxxxxxxxx> Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx> Cc: Michel Thierry <michel.thierry@xxxxxxxxx> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>From the discussion thread, Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> I assume Tvrtko is happy with the comments added based on that conversation.
Yes, all fine! Regards, Tvrtko _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
