Re: [PATCH 1/2] Customize sched domain via cpuset

[Andi Kleen <andi@firstfloor.org>]

On Tue, Apr 01, 2008 at 01:56:08PM +0200, Peter Zijlstra wrote:
> On Tue, 2008-04-01 at 13:40 +0200, Andi Kleen wrote:
> > Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> writes:
> > 
> > > Using cpuset, now we can partition the system into multiple sched domains.
> > > Then, how about providing different characteristics for each domains?
> > 
> > Did you actually see much improvement in any relevant workload
> > from tweaking these parameters?  If yes what did you change?
> > And how much did it gain?
> > 
> > Ideally the kernel should perform well without much tweaking
> > out of the box, simply because most users won't tweak. Adding a 
> > lot of such parameters would imply giving up on good defaults which 
> > is not a good thing.
> 
> >From what I understand they need very aggressive idle balancing; much
> more so than what is normally healty.
> 
> I can see how something like that can be useful when you have a lot of
> very short running tasks. These could pile up on a few cpus and leave
> others idle.

Could the scheduler auto tune itself to this situation?

e.g. when it sees a row of very high run queue inbalances increase the
frequency of the idle balancer?

-Andi