Re: [patch 2.6.16-mm2 10/9] sched throttle tree extract - kill interactive task feedback loop

[Mike Galbraith <efault@gmx.de>]

On Thu, 2006-04-06 at 09:15 +1000, Con Kolivas wrote:
> On Thursday 06 April 2006 03:38, Mike Galbraith wrote:
> > Greetings,
> >
> > The patch below stops interactive tasks from feeding off each other
> > during round-robin.
> >
> > With this 10th patch in place, a busy server with _default_ throttle
> > settings (ie tunables may now be mostly unneeded) looks like this:
> 
> > --- linux-2.6.16-mm2/kernel/sched.c-9.export_tunables	2006-03-31
> > 13:37:09.000000000 +0200 +++ linux-2.6.16-mm2/kernel/sched.c	2006-04-05
> > 19:22:01.000000000 +0200 @@ -3480,7 +3480,7 @@ go_idle:
> >  	queue = array->queue + idx;
> >  	next = list_entry(queue->next, task_t, run_list);
> >
> > -	if (!rt_task(next) && interactive_sleep(next->sleep_type)) {
> > +	if (!TASK_INTERACTIVE(next) && interactive_sleep(next->sleep_type)) {
> 
> You can't remove that rt_task check from there can you? We shouldn't ever 
> requeue a rt task.

RT tasks are always interactive aren't they?  (I'll check)

Anyway, this is definitely a large part of the problem with the ssh to
busy server, but a complete block of interactive tasks isn't quite the
right solution.  With an SMP kernel, my desktop appeared to be fine, but
a quick spin with UP kernel isn't looking quite so good.  This needs
more investigation.

	-Mike

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