extending battery-life on a macbook or in general

[Tim Smith]

> My Systems is a Macbook and Ubuntu Edgy.
> I experience in MacOS with a fully charged battery a lifetime of about 4
> to 5 hours, but with Ubuntu there is a maximum of three hours.
> Does somone have a clue what MacOS does that it is able to safe so much
> power?
> What can be done in general to extend battery-life?
> Ubuntu uses powernowd as far as I know.
> setting the mode to passive didnt give anything.
>
> I heard about the possibilitiy to set "a gouvernor" (?) in the kernel
> with somthing like
> echoing  to /dev/cpu0/...
> but also with sudo there is no way to get permission to echo into there.
> (Maybe do I have to boot from LiveCD to that?)
>
> I already turned down screen light to 50%
>
> But isnt there something that could be done beside of speedstepping and
> screendarkening? maybe switching off the harddrive (howto do that?)
>
> Again: Does someone at least have a theory about how MacOS does achive
> its battery lifetime? Could we implement something similiar?
>
> And secoundly there is the stand-by mode in MacOS.
> I can close my macbook for several days and make it return immediately
> experiencing nearly no power loss.
> I couldnt make my macbook return from standby till now so i couldnt test
> it. Just wanted to ask if standby in linux is able to do the same.
>
> greetings
> 	Hagen


A) The low battery life in Ubuntu is partially because of a bug in how
speed stepping occurs in Linux involving the dual core processors.
https://launchpad.net/distros/ubuntu/+bug/51932

B) You should be able to both suspend to RAM (aka sleep) and suspend to
disk (aka hibernate).  If you don't get options like this in the shutdown
dialog then it's not supported on the machine.

-Tim