sched: remove the sleep-bonus interactivity code

remove the sleep-bonus interactivity code from the core scheduler.

scheduling policy is implemented in the policy modules, and CFS does
not need such type of heuristics.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -894,7 +894,7 @@ static inline int __normal_prio(struct task_struct *p)
 {
 	int bonus, prio;
 
-	bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
+	bonus = 0;
 
 	prio = p->static_prio - bonus;
 	if (prio < MAX_RT_PRIO)
@@ -970,42 +970,6 @@ static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
  */
 static int recalc_task_prio(struct task_struct *p, unsigned long long now)
 {
-	/* Caller must always ensure 'now >= p->timestamp' */
-	unsigned long sleep_time = now - p->timestamp;
-
-	if (batch_task(p))
-		sleep_time = 0;
-
-	if (likely(sleep_time > 0)) {
-		/*
-		 * This ceiling is set to the lowest priority that would allow
-		 * a task to be reinserted into the active array on timeslice
-		 * completion.
-		 */
-		unsigned long ceiling = INTERACTIVE_SLEEP(p);
-
-		if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) {
-			/*
-			 * Prevents user tasks from achieving best priority
-			 * with one single large enough sleep.
-			 */
-			p->sleep_avg = ceiling;
-		} else {
-			/*
-			 * This code gives a bonus to interactive tasks.
-			 *
-			 * The boost works by updating the 'average sleep time'
-			 * value here, based on ->timestamp. The more time a
-			 * task spends sleeping, the higher the average gets -
-			 * and the higher the priority boost gets as well.
-			 */
-			p->sleep_avg += sleep_time;
-
-		}
-		if (p->sleep_avg > NS_MAX_SLEEP_AVG)
-			p->sleep_avg = NS_MAX_SLEEP_AVG;
-	}
-
 	return effective_prio(p);
 }
 
@@ -3560,9 +3524,6 @@ switch_tasks:
 	clear_tsk_need_resched(prev);
 	rcu_qsctr_inc(task_cpu(prev));
 
-	prev->sleep_avg -= run_time;
-	if ((long)prev->sleep_avg <= 0)
-		prev->sleep_avg = 0;
 	prev->timestamp = prev->last_ran = now;
 
 	sched_info_switch(prev, next);
@@ -4204,11 +4165,6 @@ static void __setscheduler(struct task_struct *p, int policy, int prio)
 	p->normal_prio = normal_prio(p);
 	/* we are holding p->pi_lock already */
 	p->prio = rt_mutex_getprio(p);
-	/*
-	 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
-	 */
-	if (policy == SCHED_BATCH)
-		p->sleep_avg = 0;
 	set_load_weight(p);
 }
 
@@ -4931,7 +4887,6 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
 	unsigned long flags;
 
 	idle->timestamp = sched_clock();
-	idle->sleep_avg = 0;
 	idle->array = NULL;
 	idle->prio = idle->normal_prio = MAX_PRIO;
 	idle->state = TASK_RUNNING;