[PATCH 28/33] drm/i915: Priority boost for new clients

[Chris Wilson]

See FQ_CODEL

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_request.c   | 16 ++++++++++++++--
 drivers/gpu/drm/i915/i915_scheduler.h |  4 +++-
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 693291762798..962b4e9024b8 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1064,8 +1064,20 @@ void __i915_request_add(struct i915_request *request, bool flush_caches)
 	 */
 	local_bh_disable();
 	rcu_read_lock(); /* RCU serialisation for set-wedged protection */
-	if (engine->schedule)
-		engine->schedule(request, &request->gem_context->sched);
+	if (engine->schedule) {
+		struct i915_sched_attr attr = request->gem_context->sched;
+
+		/*
+		 * Boost priorities to new clients (new request flows).
+		 *
+		 * Allow interactive/synchronous clients to jump ahead of
+		 * the bulk clients. (FQ_CODEL)
+		 */
+		if (!prev || i915_request_completed(prev))
+			attr.priority |= I915_PRIORITY_NEWCLIENT;
+
+		engine->schedule(request, &attr);
+	}
 	rcu_read_unlock();
 	i915_sw_fence_commit(&request->submit);
 	local_bh_enable(); /* Kick the execlists tasklet if just scheduled */
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index 7edfad0abfd7..e9fb6c1d5e42 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -19,12 +19,14 @@ enum {
 	I915_PRIORITY_INVALID = INT_MIN
 };
 
-#define I915_USER_PRIORITY_SHIFT 0
+#define I915_USER_PRIORITY_SHIFT 1
 #define I915_USER_PRIORITY(x) ((x) << I915_USER_PRIORITY_SHIFT)
 
 #define I915_PRIORITY_COUNT BIT(I915_USER_PRIORITY_SHIFT)
 #define I915_PRIORITY_MASK (-I915_PRIORITY_COUNT)
 
+#define I915_PRIORITY_NEWCLIENT BIT(0)
+
 struct i915_sched_attr {
 	/**
 	 * @priority: execution and service priority
-- 
2.17.1