[ltp] some power saving on thinkpad

[Alexey Fisher]

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Hallo lazy web!
i discovered for my thinkpad t43 powertop and tested some ways to
conserve the power.
i think i should be discussed deeper may as result some table for
thinkwiki with power eating components will be useful as result.

lets begin. here is my email i posted to powertop maelinglist:

> I just tested hpet_kernel patch on my thinkpad t43. It enabled hpet and
> made seeing cpu more idle but it does more power usage :-/
> 
> To make kernel only test i enabled init 1
> here are the results with PIT and step made difference:
> normal ubuntu setup with no patches but with NoDRI for i810 -> 16W / 100
>  wfi ( wakeups from idle )
> init 1 && remove external_usb_devices  -> 14,3W / 37,5 wfi 
> rmmod irda -> 14,2W / 37,2 wfi
> rmmod snd_intel8x0 -> 13,9W / 37,1 wfi
> hdparm -S3 /dev/sda -> 13,4W / 37,1 wfi
> brightness to min -> 10,9W / 37,1 wfi
> remove UltraBuy_CDROM -> 10,8W / 37,1 wfi
> 
> so the minimal power usage with PIT was 10,8W / 37,1 wfi idle.
> min usage with HPET is 12,0W/ 1,1 wfi!!!
> 
> the difference PIT with HPET on lowest usage for CPU are conservations
> states,
> for PIT it looks like:
> C0 1,9%
> C1 0%
> C2 0%
> C3 98,1%
> 
> for HPET:
> C0 0%
> C1 0%
> C2 36,5%
> C3 40,7%
> C4 22,8%
> 
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