Re: A few questions and issues with dynticks, NOHZ and powertop

[Arjan van de Ven]

On 4/5/2010 9:22, Paul E. McKenney wrote:
> On Mon, Apr 05, 2010 at 09:07:33AM -0700, Arjan van de Ven wrote:
> > On 4/5/2010 8:14, Paul E. McKenney wrote:
> > > So the main issue is that for many workloads, it is best to run full bore
> > > and get done quickly, thus allowing the entire machine to be powered down?
> >
> > yep
> >
> > > If so, it seems likely that there would be some workloads that were sometimes
> > > unable to use all the CPUs, in which case shutting down (idling, offlining,
> > > dyntick-idling, whatever) the excess CPUs might nevertheless be the right
> > > thing to do.
> >
> > but the point is that the normal scheduler + idle behavior gives you exactly that
> > in a natural way !
> > If you don't have enough work (tasks) to keep all cores busy, the others are and stay idle.
>
> So your earlier objection was not to dyntick-idle as such, but rather
> to artificially constraining the scheduler to induce dyntick-idle?

my objection was against the notion that offlining cpus helps power/energy ;-)

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