[Intel-gfx] [PATCH 4/6] drm/i915/scheduler: Remember request priority throughout its lifetime

[Michał Winiarski]

Since request can be unsubmitted, we need to avoid overriding its priority
during submission. Otherwise we won't be able to resubmit it with
correct priority.

v2: Limit DFS by excluding completed requests (Chris)

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c |  1 -
 drivers/gpu/drm/i915/intel_lrc.c           | 13 ++++++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 4c853fb7..e53d867 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -625,7 +625,6 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
 			}
 
 			INIT_LIST_HEAD(&rq->priotree.link);
-			rq->priotree.priority = INT_MAX;
 
 			__i915_gem_request_submit(rq);
 			trace_i915_gem_request_in(rq, port_index(port, engine));
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 5d4f23c..1255724 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -487,7 +487,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 			}
 
 			INIT_LIST_HEAD(&rq->priotree.link);
-			rq->priotree.priority = INT_MAX;
 
 			__i915_gem_request_submit(rq);
 			trace_i915_gem_request_in(rq, port_index(port, engine));
@@ -771,9 +770,17 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio)
 		 * engines.
 		 */
 		list_for_each_entry(p, &pt->signalers_list, signal_link) {
+			struct drm_i915_gem_request *s =
+				container_of(p->signaler, typeof(*s), priotree);
+
 			GEM_BUG_ON(p->signaler->priority < pt->priority);
-			if (prio > READ_ONCE(p->signaler->priority))
-				list_move_tail(&p->dfs_link, &dfs);
+			if (prio <= READ_ONCE(p->signaler->priority))
+				continue;
+
+			if (i915_gem_request_completed(s))
+				continue;
+
+			list_move_tail(&p->dfs_link, &dfs);
 		}
 
 		list_safe_reset_next(dep, p, dfs_link);
-- 
2.9.4