[Debian-eeepc-devel] saving battery

[Luca Niccoli]

On 13 February 2010 14:24, Darren Salt
<linux at youmustbejoking.demon.co.uk> wrote:
> I demand that Daniel Dalton may or may not have written...
>
> [snip; 1008HA]
>> What else can I do to save battery? I read somewhere I can throttle down
>> the cpu speed when necessary? Or is this a dangerous procedure?
>
> You can; for most, it works well. (I've only heard from one for whom
> *over*clocking failed.)
>
> eeepc-acpi-scripts has code to do this. Since 1.1.3, it'll default to
> "automatic" at boot (if previously unconfigured); 1.1.6 and later allow user
> of the S.H.E. control key (either Fn-Space or a separate button).
>
> You can force default settings by deleting /var/lib/eeepc-acpi-scripts/cpufv.

Just to clarify:

dynamic frequency scaling should be activated by default in every
debian system that supports it; the governor "ondemand" raises the CPU
frequency whenever needed; this in fact is arguably the most battery
friendly behaviour, better than keeping the CPU always at its minimum
speed.

Many Eeepcs also have a proprietary way of adjusting FSB speed and
voltage; this works in parallel to the normal throttling.
On my 901 this makes quite a difference, I think I get almost one hour
more on the most conservative setting.
The default "automatic" means that it will throttle the FSB as much as
possible when on battery, and set the normal speed when on AC, if I'm
not mistaken.
I think that eeepc-acpi-scripts offer only the option of a visual Xorg
feedback for pressing the S.H.E. key, so if the automatic throttling
is good for you, you might want to configure the S.H.E. key to do
nothing (or something else) in /etc/default/eeepc-acpi-settings not to
change throttling inadvertently (I did so as I don't have the OSD
activated and a couple of time I ran out of battery before I expected
because of this)

Cheers,

Luca