Commit b1ad5f6d authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/gt: Only retire on the last breadcrumb if the last request 



We use the completion of the last active breadcrumb to retire the
requests along a timeline. This is purely opportunistic as nothing
guarantees that any particular timeline is terminated by a breadcrumb;
except for parking the engine where we explicitly add a breadcrumb so
that we park quickly and do an explicit retire upon signaling to reduce
the latency dramatically (avoiding a retire worker roundtrip).

With scheduling, we anticipate retiring completed timelines as a matter
of course. Performing the same action from inside the breadcrumbs is
intended to provide similar functionality for legacy ringbuffer
submission.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210108204026.20682-5-chris@chris-wilson.co.uk
parent 2b2985a4

drivers/gpu/drm/i915/gt/intel_breadcrumbs.c

+5 −5
Original line number Diff line number Diff line
@@ -257,17 +257,17 @@ static void signal_irq_work(struct irq_work *work) 
			list_del_rcu(&rq->signal_link);

			release = remove_signaling_context(b, ce);

			spin_unlock(&ce->signal_lock);

			if (release) {

				if (intel_timeline_is_last(ce->timeline, rq))

					add_retire(b, ce->timeline);

				intel_context_put(ce);

			}



			if (__dma_fence_signal(&rq->fence))

				/* We own signal_node now, xfer to local list */

				signal = slist_add(&rq->signal_node, signal);

			else

				i915_request_put(rq);



			if (release) {

				add_retire(b, ce->timeline);

				intel_context_put(ce);

			}

		}

	}

	atomic_dec(&b->signaler_active);

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

+1 −1
Original line number Diff line number Diff line
@@ -640,7 +640,7 @@ static inline void __execlists_schedule_out(struct i915_request *rq) 
	 * If we have just completed this context, the engine may now be

	 * idle and we want to re-enter powersaving.

	 */

	if (list_is_last_rcu(&rq->link, &ce->timeline->requests) &&

	if (intel_timeline_is_last(ce->timeline, rq) &&

	    __i915_request_is_complete(rq))

		intel_engine_add_retire(engine, ce->timeline);

drivers/gpu/drm/i915/gt/intel_timeline.h

+7 −0
Original line number Diff line number Diff line
@@ -110,4 +110,11 @@ void intel_gt_show_timelines(struct intel_gt *gt, 
						  const char *prefix,

						  int indent));



static inline bool

intel_timeline_is_last(const struct intel_timeline *tl,

		       const struct i915_request *rq)

{

	return list_is_last_rcu(&rq->link, &tl->requests);

}



#endif