Re: [RFC v1] Tunable sched_mc_power_savings=n

[Matthew Garrett <mjg59@srcf.ucam.org>]

On Sat, Jun 28, 2008 at 02:36:02PM +0200, Andi Kleen wrote:

> For example if you're in a data center at a specific operating point and
> you would need to crank up the air condition at significant power cost it might
> be well better overall to force all servers to a lower operating point
> and avoid that.

Sure, there are cases where you have additional constraints. But within 
those constraints, you probably want to run as fast as possible.

> That said in general you all should have complained when ondemand behaviour
> was introduced.

ignore_nice seems to be set to 0 by default?

> Also it's unclear that the general "race to idle" heuristic really
> applies to the case of the "keep sockets idle" power optimization
> that started this thread.
> 
> Usually package C states bring much more than core C states
> and keeping another package completely idle saves likely
> more power than the power cost of running something a little
> bit slower on a package that is already busy on another core.

I'd agree with that.
-- 
Matthew Garrett | mjg59@srcf.ucam.org