[PATCH 2/2] drm/amd/sched: add schuduling policy

[Chunming Zhou]

if high priority rq is full, then process with low priority could be starve.
Add policy for this problem, the high proiority can ahead of next priority queue,
the ratio is 2 : 1.

Change-Id: I58f4a6b9cdce8689b18dd8e83dd6e2cf5f99d5fb
Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
---
 drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 26 +++++++++++++++++++++++---
 drivers/gpu/drm/amd/scheduler/gpu_scheduler.h |  2 ++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
index 0f439dd..4637b6f 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
@@ -35,11 +35,16 @@
 static void amd_sched_process_job(struct fence *f, struct fence_cb *cb);
 
 /* Initialize a given run queue struct */
-static void amd_sched_rq_init(struct amd_sched_rq *rq)
+static void amd_sched_rq_init(struct amd_gpu_scheduler *sched, enum
+			      amd_sched_priority pri)
 {
+	struct amd_sched_rq *rq = &sched->sched_rq[pri];
+
 	spin_lock_init(&rq->lock);
 	INIT_LIST_HEAD(&rq->entities);
 	rq->current_entity = NULL;
+	rq->wait_base = pri * 2;
+	rq->wait = rq->wait_base;
 }
 
 static void amd_sched_rq_add_entity(struct amd_sched_rq *rq,
@@ -494,17 +499,32 @@ static void amd_sched_wakeup(struct amd_gpu_scheduler *sched)
 {
 	struct amd_sched_entity *entity;
 	int i;
+	bool skip;
 
 	if (!amd_sched_ready(sched))
 		return NULL;
 
+retry:
+	skip = false;
 	/* Kernel run queue has higher priority than normal run queue*/
 	for (i = AMD_SCHED_PRIORITY_MAX - 1; i >= AMD_SCHED_PRIORITY_MIN; i--) {
+		if ((i > AMD_SCHED_PRIORITY_MIN) &&
+		    (sched->sched_rq[i - 1].wait >= sched->sched_rq[i].wait_base)) {
+			sched->sched_rq[i - 1].wait = sched->sched_rq[i - 1].wait_base;
+			skip = true;
+			continue;
+		}
 		entity = amd_sched_rq_select_entity(&sched->sched_rq[i]);
-		if (entity)
+		if (entity) {
+			if (i > AMD_SCHED_PRIORITY_MIN)
+				sched->sched_rq[i - 1].wait++;
 			break;
+		}
 	}
 
+	if (!entity && skip)
+		goto retry;
+
 	return entity;
 }
 
@@ -608,7 +628,7 @@ int amd_sched_init(struct amd_gpu_scheduler *sched,
 	sched->name = name;
 	sched->timeout = timeout;
 	for (i = AMD_SCHED_PRIORITY_MIN; i < AMD_SCHED_PRIORITY_MAX; i++)
-		amd_sched_rq_init(&sched->sched_rq[i]);
+		amd_sched_rq_init(sched, i);
 
 	init_waitqueue_head(&sched->wake_up_worker);
 	init_waitqueue_head(&sched->job_scheduled);
diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
index 99f0240..4caed30 100644
--- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
+++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
@@ -64,6 +64,8 @@ struct amd_sched_rq {
 	spinlock_t		lock;
 	struct list_head	entities;
 	struct amd_sched_entity	*current_entity;
+	int wait_base;
+	int wait;
 };
 
 struct amd_sched_fence {
-- 
1.9.1