time slice cfq comments

[Con Kolivas <kernel@kolivas.org>]

Hi Jens

Just thought I'd make a few comments about some of the code in your time 
sliced cfq.

+	if (p->array)
+		return min(cpu_curr(task_cpu(p))->time_slice,
+					(unsigned int)MAX_SLEEP_AVG);

MAX_SLEEP_AVG is basically 10 * the average time_slice so this will 
always return task_cpu(p)->time_slice as the min value (except for the 
race you described in your comments). What you probably want is

+		return min(cpu_curr(task_cpu(p))->time_slice,
+					(unsigned int)DEF_TIMESLICE);


Further down you do:
+	/*
+	 * for blocked tasks, return half of the average sleep time.
+	 * (because this is the average sleep-time we'll see if we
+	 * sample the period randomly.)
+	 */
+	return NS_TO_JIFFIES(p->sleep_avg) / 2;

unfortunately p->sleep_avg is a non-linear value (weighted upwards 
towards MAX_SLEEP_AVG). I suspect here you want

+	return NS_TO_JIFFIES(p->sleep_avg) / MAX_BONUS;

I don't see any need for / 2.

Cheers,
Con