From 152d3096a5be93c8f2671eb371520980f40e1c39 Mon Sep 17 00:00:00 2001
From: Marc Fiuczynski <mef@cs.princeton.edu>
Date: Mon, 18 Oct 2004 13:24:29 +0000
Subject: [PATCH] version 9.1 of the ckrm cpu scheduler.

---
 kernel/sched.c | 67 +++++++++++++++++++++++++-------------------------
 1 file changed, 34 insertions(+), 33 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 947dda24e..20b09215e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -349,36 +349,35 @@ static inline struct task_struct * rq_get_next_task(struct runqueue* rq)
 	ckrm_lrq_t *queue;
 	int idx;
 	int cpu = smp_processor_id();
-	
-	next = rq->idle;
+
+	// it is guaranteed be the ( rq->nr_running > 0 ) check in 
+	// schedule that a task will be found.
+
  retry_next_class:
-	if ((queue = rq_get_next_class(rq))) {
-		//check switch active/expired queue
-		array = queue->active;
-		if (unlikely(!array->nr_active)) {
-			queue->active = queue->expired;
-			queue->expired = array;
-			queue->expired_timestamp = 0;
-
-			if (queue->active->nr_active)
-				set_top_priority(queue,
-						 find_first_bit(queue->active->bitmap, MAX_PRIO));
-			else {
-				classqueue_dequeue(queue->classqueue,
-						   &queue->classqueue_linkobj);
-				cpu_demand_event(get_rq_local_stat(queue,cpu),CPU_DEMAND_DEQUEUE,0);
-			}
-			goto retry_next_class; 				
-		}
-		BUG_ON(!array->nr_active);
+	queue = rq_get_next_class(rq);
+	// BUG_ON( !queue );
 
-		idx = queue->top_priority;
-		if (queue->top_priority == MAX_PRIO) {
-			BUG_ON(1);
-		}
+	array = queue->active;
+	if (unlikely(!array->nr_active)) {
+		queue->active = queue->expired;
+		queue->expired = array;
+		queue->expired_timestamp = 0;
 
-		next = task_list_entry(array->queue[idx].next);
+		if (queue->active->nr_active)
+			set_top_priority(queue,
+					 find_first_bit(queue->active->bitmap, MAX_PRIO));
+		else {
+			classqueue_dequeue(queue->classqueue,
+					   &queue->classqueue_linkobj);
+			cpu_demand_event(get_rq_local_stat(queue,cpu),CPU_DEMAND_DEQUEUE,0);
+		}
+		goto retry_next_class; 				
 	}
+	// BUG_ON(!array->nr_active);
+
+	idx = queue->top_priority;
+	// BUG_ON (idx == MAX_PRIO);
+	next = task_list_entry(array->queue[idx].next);
 	return next;
 }
 #else /*! CONFIG_CKRM_CPU_SCHEDULE*/
@@ -417,7 +416,6 @@ static inline void ckrm_sched_tick(int j,int this_cpu,void* name) {}
  */
 static void dequeue_task(struct task_struct *p, prio_array_t *array)
 {
-	BUG_ON(! array);
 	array->nr_active--;
 	list_del(&p->run_list);
 	if (list_empty(array->queue + p->prio))
@@ -2533,7 +2531,7 @@ static inline int wake_priority_sleeper(runqueue_t *rq)
 	return 0;
 }
 
-DEFINE_PER_CPU(struct kernel_stat, kstat) = { { 0 } };
+DEFINE_PER_CPU(struct kernel_stat, kstat);
 EXPORT_PER_CPU_SYMBOL(kstat);
 
 /*
@@ -2900,14 +2898,17 @@ pick_next:
 #endif
 	if (unlikely(!rq->nr_running)) {
 		idle_balance(cpu, rq);
+                if (!rq->nr_running) {
+                        next = rq->idle;
+#ifdef CONFIG_CKRM_CPU_SCHEDULE
+                        rq->expired_timestamp = 0;
+#endif
+                        wake_sleeping_dependent(cpu, rq);
+                        goto switch_tasks;
+                }
 	}
 
 	next = rq_get_next_task(rq);
-	if (next == rq->idle) {
-		rq->expired_timestamp = 0;
-		wake_sleeping_dependent(cpu, rq);
-		goto switch_tasks;
-	}
 
 	if (dependent_sleeper(cpu, rq, next)) {
 		next = rq->idle;
-- 
2.47.0