Re: [RFC PATCH v2 0/2] Saving power by cpu evacuation sched_max_capacity_pct=n

Andi Kleen
2009-05-13T14:41:48Z

On Wed, May 13, 2009 at 04:36:42PM +0200, Peter Zijlstra wrote:
> On Wed, 2009-05-13 at 16:35 +0200, Andi Kleen wrote:
> > On Wed, May 13, 2009 at 06:41:00PM +0530, Vaidyanathan Srinivasan wrote:
> > > * Using sched_mc=3,4,5 to evacuate 1,2,4 cores is completely
> > > non-intuitive and broken interface. Ingo wanted to see if we can
> > > model a global percentile tunable that would map to core throttling.
> >
> > I have one request. CPU throttling is already a very well established
> > term in the x86 world, refering to thermal throttling when the CPU
> > overheats. This is implemented by ACPI and the CPU. It's always
> > a very bad thing that should be avoided at all costs.
>
> Its about avoiding that.

Hmm? Can you explain please? CPU throttling should only happen when your
cooling system is broken in some way.

It's not a power saving feature, just a "don't make CPU melt" feature.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.