Re: [discussion]sched: a rough proposal to enable power saving in scheduler

[Mike Galbraith <efault@gmx.de>]

On Wed, 2012-08-22 at 06:02 -0700, Arjan van de Ven wrote: 
> On 8/21/2012 10:41 PM, Mike Galbraith wrote:
> > On Tue, 2012-08-21 at 17:02 +0100, Alan Cox wrote:
> > 
> >> I'd like to see actual numbers and evidence on a wide range of workloads
> >> the spread/don't spread thing is even measurable given that you've also
> >> got to factor in effects like completing faster and turning everything
> >> off. I'd *really* like to see such evidence on a laptop,which is your
> >> one cited case it might work.
> > 
> > For my dinky dual core laptop, I suspect you're right, but for a more
> > powerful laptop, I'd expect spread/don't to be noticeable.
> 
> yeah if you don't spread, you will waste some power.
> but.. current linux behavior is to spread.
> so we can only make it worse.

Hm, so I can stop fretting about select_idle_sibling().  Good. 

> > Yeah, hard numbers would be nice to see.
> > 
> > If I had a powerful laptop, I'd kill irq balancing, and all but periodic
> > load balancing, and expect to see a positive result. 
> 
> I'd expect to see a negative result ;-)

Ok, so I have my head on backward.  Gives a different perspective :)

-Mike