Power Saving Tips

I was thinking of putting Ubuntu back on my notebook. One thing I didn't like about it is it seems in my case to get less battery life. It used to get about three hours on battery while Windows got four. Anyone got any tips for getting better battery life in Ubuntu? I don't need it to be exactly the same, but something closer would be nice. Thanks for any help.

 

Linux distros are as good as they're going to get out of the box, really. Unlike Windows, tweaking isn't as easy unless you are very much at home using the command line.

That said, there is Intels PowerTop application that allows you to make power management tweaks. Undervolting is another option, although it is ridiculously complicated as it requires a recompiled kernel in order to accomodate the patch. You could also set the processor to run at its lowest clock speed with a minimal performance hit, since Ubuntu isn't very demanding.

 

So I'm basically hosed?

 

Just shut down all services you arent using. There is a lot of bloat in Ubuntu out of the box that most people don't need.

 

If I knew the ins and outs of Linux, and how the kernel deals with power management, I would guide you through setting up Gentoo with heavily customized power options, but I don't. :/

I would, however, advise that you at least try putting Gentoo (or even Arch) together yourself; both distros are supposed to have outstanding documentation on how to set up a system, as complicated as it is.

 

I also recommend PowerTop. Have you tried it?

And you will find many interesting tips here.

 

It's really not that big of a deal to undervolt (Lenovo T61/T7300/120GB HDD/4GB RAM here). It just requires a replacement ACPI module, it doesn't require a full new kernel recompile. I'm still running the stock 64bit Ubuntu 8.04 kernel, but I'm undervolting to about 2/3rds of the default voltages on the higher frequencies. It's giving me much better battery life, and it runs cooler to boot.

Powertop is great, too. Make sure you know what the suggestions mean, though. Stuff like disabling HAL polling for your cdrom means that it won't automatically mount a CD-ROM or even put the icon on your desktop any more. But turning off the radios if you don't need them is a great piece of advice (especially bluetooth). And turn down the brightness as low as you can go while still functioning. Between those, you'll extend your battery life quite a bit. And of course make sure you use an on-demand frequency scheduler, rather than setting it to performance or whatnot.

 

I think that, in a nutshell, is my problem. I don't know how to use Powertop. Is there any kind of guide/FAQ for it?

 

Just run powertop. It's pretty well self-documenting as far as what it suggests. If you're confused, take the suggestion it makes to Google, and if you're in doubt, post it here I can't find any "how-to's", but just running powertop will give you a good idea of what part of your machine is eating up the power the most.

 

Are modern kernels tickless? I remember reading an article about it a while back them.

 

Yes, since 2.6.21

 

Check out this post: http://guilleml.wordpress.com/2008/09/09/increase-battery-life-in-your-linux-laptop/.

Good stuff for ubuntu and Debian power saving on a laptop.

Cheers,

Michael