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

[Arjan van de Ven <arjan@linux.intel.com>]

>>> A modern kernel better know what state the system is in: on 
>>> battery or on AC power.
>>
>> That's a fundamentally uninteresting thing for the kernel to 
>> know about. [...]
> 
> I disagree.

and I'll agree with Matthew and disagree with you ;-)

> 
>> [...] AC/battery is just not an important power management 
>> policy input when compared to various other things.
> 
> Such as?
> 
> The thing is, when I use Linux on a laptop then AC/battery is 
> *the* main policy input.

I think you're wrong there.
First of all, not the whole world is a laptop.
Phones and servers are very different than laptops in this sense.
In a phone, when you're charging, you want to be EXTRA power efficient in many ways
(since charging creates heat, and that heat will take away your thermal budget).
In a datacenter, you're either on AC or DC all the time, and power efficiency still matters.

And even on a laptop.. heat production matters even when on AC... laptops are more and more like phones
that way.