[PATCH] O1int for 2.5.73

[Con Kolivas <kernel@kolivas.org>]

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Here is an updated version of the O1int patch designed to improve 
interactivity.

This change addresses the difficulty of new tasks in heavy load being 
recognised as interactive by decreasing the amount of time considered in the 
interactivity equation, but dropping that decrease exponentially till it gets 
to the MAX_SLEEP_AVG.

This should improve the startup time of new apps in heavy load and lessen 
audio stalls when loads are high _and_ then the audio app is started.

Please test and comment.

Con

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diff -Naurp linux-2.5.73/include/linux/sched.h linux-2.5.73-test/include/linux/sched.h
--- linux-2.5.73/include/linux/sched.h	2003-06-26 01:30:42.000000000 +1000
+++ linux-2.5.73-test/include/linux/sched.h	2003-06-26 01:32:34.000000000 +1000
@@ -336,6 +336,7 @@ struct task_struct {
 	prio_array_t *array;
 
 	unsigned long sleep_avg;
+	unsigned long avg_start;
 	unsigned long last_run;
 
 	unsigned long policy;
diff -Naurp linux-2.5.73/kernel/fork.c linux-2.5.73-test/kernel/fork.c
--- linux-2.5.73/kernel/fork.c	2003-06-26 01:30:42.000000000 +1000
+++ linux-2.5.73-test/kernel/fork.c	2003-06-26 01:33:31.000000000 +1000
@@ -863,6 +863,7 @@ struct task_struct *copy_process(unsigne
 	p->array = NULL;
 	p->lock_depth = -1;		/* -1 = no lock */
 	p->start_time = get_jiffies_64();
+	p->avg_start = jiffies;
 	p->security = NULL;
 
 	retval = -ENOMEM;
diff -Naurp linux-2.5.73/kernel/sched.c linux-2.5.73-test/kernel/sched.c
--- linux-2.5.73/kernel/sched.c	2003-06-26 01:30:42.000000000 +1000
+++ linux-2.5.73-test/kernel/sched.c	2003-06-27 18:15:59.000000000 +1000
@@ -313,12 +313,24 @@ static inline void enqueue_task(struct t
  */
 static int effective_prio(task_t *p)
 {
-	int bonus, prio;
+	int bonus, prio, sleep_period;
 
 	if (rt_task(p))
 		return p->prio;
 
-	bonus = MAX_USER_PRIO*PRIO_BONUS_RATIO*p->sleep_avg/MAX_SLEEP_AVG/100 -
+	sleep_period = jiffies - p->avg_start;
+
+	if (sleep_period > MAX_SLEEP_AVG)
+		sleep_period = MAX_SLEEP_AVG;
+	else if (sleep_period < 10)
+		return p->static_prio;
+
+	if (sleep_period < MAX_SLEEP_AVG)
+		sleep_period -= (sleep_period/2) * (MAX_SLEEP_AVG - sleep_period)/MAX_SLEEP_AVG;
+	if (p->sleep_avg > sleep_period)
+		sleep_period = p->sleep_avg;
+
+	bonus = MAX_USER_PRIO*PRIO_BONUS_RATIO*p->sleep_avg/sleep_period/100 -
 			MAX_USER_PRIO*PRIO_BONUS_RATIO/100/2;
 
 	prio = p->static_prio - bonus;
@@ -349,8 +361,12 @@ static inline void activate_task(task_t 
 	long sleep_time = jiffies - p->last_run - 1;
 
 	if (sleep_time > 0) {
-		int sleep_avg;
 
+		if (sleep_time > HZ){
+			p->avg_start = jiffies - HZ;
+			p->sleep_avg = HZ / 2;
+		}
+		else {
 		/*
 		 * This code gives a bonus to interactive tasks.
 		 *
@@ -359,7 +375,7 @@ static inline void activate_task(task_t 
 		 * spends sleeping, the higher the average gets - and the
 		 * higher the priority boost gets as well.
 		 */
-		sleep_avg = p->sleep_avg + sleep_time;
+			p->sleep_avg += sleep_time;
 
 		/*
 		 * 'Overflow' bonus ticks go to the waker as well, so the
@@ -367,12 +383,10 @@ static inline void activate_task(task_t 
 		 * boosting tasks that are related to maximum-interactive
 		 * tasks.
 		 */
-		if (sleep_avg > MAX_SLEEP_AVG)
-			sleep_avg = MAX_SLEEP_AVG;
-		if (p->sleep_avg != sleep_avg) {
-			p->sleep_avg = sleep_avg;
-			p->prio = effective_prio(p);
+			if (p->sleep_avg > MAX_SLEEP_AVG)
+				p->sleep_avg = MAX_SLEEP_AVG;
 		}
+		p->prio = effective_prio(p);
 	}
 	__activate_task(p, rq);
 }
@@ -549,8 +563,6 @@ void wake_up_forked_process(task_t * p)
 	 * and children as well, to keep max-interactive tasks
 	 * from forking tasks that are max-interactive.
 	 */
-	current->sleep_avg = current->sleep_avg * PARENT_PENALTY / 100;
-	p->sleep_avg = p->sleep_avg * CHILD_PENALTY / 100;
 	p->prio = effective_prio(p);
 	set_task_cpu(p, smp_processor_id());
 
@@ -586,13 +598,6 @@ void sched_exit(task_t * p)
 			p->parent->time_slice = MAX_TIMESLICE;
 	}
 	local_irq_restore(flags);
-	/*
-	 * If the child was a (relative-) CPU hog then decrease
-	 * the sleep_avg of the parent as well.
-	 */
-	if (p->sleep_avg < p->parent->sleep_avg)
-		p->parent->sleep_avg = (p->parent->sleep_avg * EXIT_WEIGHT +
-			p->sleep_avg) / (EXIT_WEIGHT + 1);
 }
 
 /**