Re: bug in sched.c:activate_task()

[Con Kolivas <kernel@kolivas.org>]

Ingo Molnar writes:

> 
> On Mon, 4 Oct 2004, Chen, Kenneth W wrote:
> 
>> Update p->timestamp to "now" in activate_task() doesn't look right to me
>> at all.  p->timestamp records last time it was running on a cpu.  
>> activate_task shouldn't update that variable when it queues a task on
>> the runqueue.
> 
> correct, we are overriding it in schedule():
> 
>         if (likely(prev != next)) {
>                 next->timestamp = now;
>                 rq->nr_switches++;
> 
> the line your patch removes is a remnant of an earlier logic when we
> timestamped tasks when they touched the runqueue. (vs. timestamping when
> they actually run on a CPU.) So the patch looks good to me. Andrew, please
> apply.

	unsigned long long delta = now - next->timestamp;

	if (next->activated == 1)
		delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;

is in schedule() before we update the timestamp, no?

Con