Re: [SCHED] wrong priority calc - SIMPLE test case

[Mike Galbraith <efault@gmx.de>]

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At 01:56 PM 1/10/2006 +0100, Paolo Ornati wrote:
>On Tue, 10 Jan 2006 13:07:33 +0100
>Mike Galbraith <efault@gmx.de> wrote:
>
> > Can you please try this version?  It tries harder to correct any
>
>It seems that you have forgotten the to attach the patch...

Drat.  At least I'm not the first to ever do so :)

(double checks)  It's now attached.

         -Mike   

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--- linux-2.6.15/include/linux/sched.h.org	Tue Jan  3 09:26:50 2006
+++ linux-2.6.15/include/linux/sched.h	Sat Jan  7 14:45:37 2006
@@ -701,8 +701,8 @@
 
 	unsigned short ioprio;
 
-	unsigned long sleep_avg;
-	unsigned long long timestamp, last_ran;
+	unsigned long sleep_avg, slice_avg;
+	unsigned long long timestamp, last_ran, last_slice;
 	unsigned long long sched_time; /* sched_clock time spent running */
 	int activated;
 
--- linux-2.6.15/kernel/sched.c.org	Sat Jan  7 16:22:13 2006
+++ linux-2.6.15/kernel/sched.c	Tue Jan 10 13:59:44 2006
@@ -127,6 +127,20 @@
 	(NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
 		MAX_SLEEP_AVG)
 
+/*
+ * If a task's sleep_avg strays too far from it's slice_avg, this
+ * task is using more cpu than it's sleep_avg would indicate. When
+ * such a disparity is detected, prevent additional sleep time from
+ * being added to the existing imbalance, and increase the rate at
+ * which sleep_average is consumed.
+ */
+#define SLEEP_AVG_IMBALANCE(p) \
+	((p)->sleep_avg > (p)->slice_avg + (NS_MAX_SLEEP_AVG/10))
+
+#define CPU_PENALTY(p) \
+	(NS_TO_JIFFIES(min((p)->sleep_avg, (p)->slice_avg)) * MAX_BONUS / \
+		MAX_SLEEP_AVG)
+
 #define GRANULARITY	(10 * HZ / 1000 ? : 1)
 
 #ifdef CONFIG_SMP
@@ -744,7 +758,7 @@
 	else
 		sleep_time = (unsigned long)__sleep_time;
 
-	if (likely(sleep_time > 0)) {
+	if (likely(sleep_time > 0 && !SLEEP_AVG_IMBALANCE(p))) {
 		/*
 		 * User tasks that sleep a long time are categorised as
 		 * idle and will get just interactive status to stay active &
@@ -1353,7 +1367,7 @@
 
 out_activate:
 #endif /* CONFIG_SMP */
-	if (old_state == TASK_UNINTERRUPTIBLE) {
+	if (old_state & TASK_UNINTERRUPTIBLE) {
 		rq->nr_uninterruptible--;
 		/*
 		 * Tasks on involuntary sleep don't earn
@@ -1368,7 +1382,7 @@
 	 * sleep is handled in a priority-neutral manner, no priority
 	 * boost and no penalty.)
 	 */
-	if (old_state & TASK_NONINTERACTIVE)
+	if (old_state & TASK_NONINTERACTIVE || SLEEP_AVG_IMBALANCE(p))
 		__activate_task(p, rq);
 	else
 		activate_task(p, rq, cpu == this_cpu);
@@ -1492,6 +1506,8 @@
 	 */
 	p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
 		CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
+	p->slice_avg = NS_MAX_SLEEP_AVG;
+	p->last_slice = sched_clock();
 
 	p->prio = effective_prio(p);
 
@@ -2679,6 +2695,7 @@
 		if ((p->policy == SCHED_RR) && !--p->time_slice) {
 			p->time_slice = task_timeslice(p);
 			p->first_time_slice = 0;
+			p->last_slice = now;
 			set_tsk_need_resched(p);
 
 			/* put it at the end of the queue: */
@@ -2687,12 +2704,33 @@
 		goto out_unlock;
 	}
 	if (!--p->time_slice) {
+		unsigned long long nsecs = now - p->last_slice;
+		unsigned long idle, ticks;
+		int w = 10;
+
 		dequeue_task(p, rq->active);
 		set_tsk_need_resched(p);
 		p->prio = effective_prio(p);
 		p->time_slice = task_timeslice(p);
 		p->first_time_slice = 0;
 
+		if (nsecs > ~0UL)
+			nsecs = ~0UL;
+		ticks = NS_TO_JIFFIES((unsigned long) nsecs);
+		if (ticks < p->time_slice)
+			ticks = p->time_slice;
+		idle = 100 - (100 * p->time_slice / ticks);
+		p->slice_avg /= NS_MAX_SLEEP_AVG / 100;
+		/*
+		 * If the task is lowering it's cpu usage, speed up the
+		 * effect on slice_avg so we don't over throttle.
+		 */
+		if (idle > p->slice_avg + 10)
+			w -= (100 * p->slice_avg / idle) / 10;
+		p->slice_avg = (w * p->slice_avg + idle) / (w + 1);
+		p->slice_avg *= NS_MAX_SLEEP_AVG / 100;
+		p->last_slice = now;
+
 		if (!rq->expired_timestamp)
 			rq->expired_timestamp = jiffies;
 		if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) {
@@ -2996,7 +3034,7 @@
 	 * Tasks charged proportionately less run_time at high sleep_avg to
 	 * delay them losing their interactive status
 	 */
-	run_time /= (CURRENT_BONUS(prev) ? : 1);
+	run_time /= (CPU_PENALTY(prev) ? : 1);
 
 	spin_lock_irq(&rq->lock);
 
@@ -3010,7 +3048,7 @@
 				unlikely(signal_pending(prev))))
 			prev->state = TASK_RUNNING;
 		else {
-			if (prev->state == TASK_UNINTERRUPTIBLE)
+			if (prev->state & TASK_UNINTERRUPTIBLE)
 				rq->nr_uninterruptible++;
 			deactivate_task(prev, rq);
 		}
@@ -3095,6 +3133,12 @@
 	prev->sleep_avg -= run_time;
 	if ((long)prev->sleep_avg <= 0)
 		prev->sleep_avg = 0;
+	/*
+	 * Enable detection of the beginning of a slice at tick time.
+	 */
+	if (!rt_task(next) && !(next->time_slice % DEF_TIMESLICE))
+		next->last_slice = now;
+
 	prev->timestamp = prev->last_ran = now;
 
 	sched_info_switch(prev, next);