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

From: Arjan van de Ven
Date: Fri Aug 17 2012 - 14:44:13 EST


On 8/17/2012 11:41 AM, Matthew Garrett wrote:
> On Thu, Aug 16, 2012 at 07:01:25AM -0700, Arjan van de Ven wrote:
>>> *Power policy*:
>>>
>>> So how is power policy different? As Peter says,'pack more than spread
>>> more'.
>>
>> this is ... a dubiously general statement.
>>
>> for good power, at least on Intel cpus, you want to spread. Parallelism is efficient.
>
> Is this really true? In a two-socket system I'd have thought the benefit
> of keeping socket 1 in package C3 outweighed the cost of keeping socket
> 0 awake for slightly longer.

not on Intel

you can't enter package c3 either until every one is down.
(e.g. memory controller must stay on etc etc)

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