Power-Mgt (Was: Re: cvs commit: src/sys/i386/cpufreq est.c )

[Poul-Henning Kamp]

In message <20080317141717.U3253 at fledge.watson.org>, Robert Watson writes:

>If cpufreq is going to be enabled by default, should we be enabling powerd by 
>default [...]

[Moved to arch@]

In general, I think we must make power-aware computing our "next
SMPng project", not in the sense of delaying the next major release
five years, but in the sense that power consumption should permerate
our thinking about the operating system from now on.

Overall, I think that means that we should:

*  Enable performance neutral power savings on servers
	- spin down unused disks. (geom/drivers)
	- use only as many CPU cores as necessary (scheduler)
	- light cpu-throttling.
	- downgrading 1GB to 100MB ether when idle.

*  Aim to meet or execeed energystar 4.0/5.0[1] on desktops and 
   plugged laptops.
	- Pretty much as above, but with specific targets.
	- http://www.energystar.gov/index.cfm?c=revisions.computer_spec

*  Be as battery-frugal as possible on battery driven laptops.
	- Any trick in and off the book.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.