[PATCH 31/39] drm/i915/execlists: Skip direct submission if only lite-restore

[Chris Wilson]

If resubmitting the active context, simply skip the submission as
performing the submission from the interrupt handler has higher
throughput than continually provoking lite-restores. If however, we find
ourselves with a new client, we check whether or not we can dequeue into
the second port or to resolve preemption.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_lrc.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 737205a678bc..00c23ec8b02f 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1396,12 +1396,26 @@ static void __submit_queue_imm(struct intel_engine_cs *engine)
 		tasklet_hi_schedule(&execlists->tasklet);
 }
 
-static void submit_queue(struct intel_engine_cs *engine, int prio)
+static bool inflight(const struct intel_engine_execlists *execlists,
+		     const struct i915_request *rq)
 {
-	if (prio > engine->execlists.queue_priority_hint) {
-		engine->execlists.queue_priority_hint = prio;
+	const struct i915_request *active = port_request(execlists->port);
+
+	return active && active->hw_context == rq->hw_context;
+}
+
+static void submit_queue(struct intel_engine_cs *engine,
+			 const struct i915_request *rq)
+{
+	struct intel_engine_execlists *execlists = &engine->execlists;
+
+	if (rq_prio(rq) <= execlists->queue_priority_hint)
+		return;
+
+	execlists->queue_priority_hint = rq_prio(rq);
+
+	if (!inflight(execlists, rq))
 		__submit_queue_imm(engine);
-	}
 }
 
 static void execlists_submit_request(struct i915_request *request)
@@ -1417,7 +1431,7 @@ static void execlists_submit_request(struct i915_request *request)
 	GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
 	GEM_BUG_ON(list_empty(&request->sched.link));
 
-	submit_queue(engine, rq_prio(request));
+	submit_queue(engine, request);
 
 	spin_unlock_irqrestore(&engine->timeline.lock, flags);
 }
-- 
2.20.1