Re: [gentoo-user] MacBook: How many hours on battery with Gentoo?

[Florian Philipp <lists@f_philipp.fastmail.net>]

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On Tue, 2008-02-19 at 20:07 +0100, b.n. wrote:
> Ritesh Kumar ha scritto:
> > On Feb 19, 2008 12:09 PM, Florian Philipp <lists@f_philipp.fastmail.net>
> > wrote:
> > 
> > 
> >     On Tue, 2008-02-19 at 11:28 +0100, b.n. wrote:
> >     > Lowe Schmidt ha scritto:
> >     > > Hi.
> >     > >
> >     > > I'm planning on buying myself a MacBook and I'm just wondering
> >     if anyone
> >     > > knows how many hours I will get out of it if I run Gentoo. I
> >     mainly use
> >     > > a bunch
> >     > > of terminals, gvim and some lightweigth gtk app so nothing heavy
> >     going on.
> >     > >
> >     > > All input appreciated
> >     >
> >     > My Macbook Pro with light, normal usage lasts about three hours (OS X
> >     > lasts at least one hour more).
> >     >
> >     > m.
> > 
> >     Have you found any reason for this discrepancy? I'd suspect them to be
> >     on par with the right tuning.
> > 
> > 
> > Are you doing any kind of CPU frequency scaling? In the kernel (I use
> > gentoo sources) configuration enable
> 
> Yes, I do frequency scaling (the ondemand governor is used when the
> laptop is unplugged). I also use laptop-mode for the hd and pommed to
> tune screen brightness.
> 
> I think the problems are the wireless and the video drivers. The new
> Macbook Pro wireless drivers (I bought my machine in late October 2007,
> just when Leopard came out -although, well, I found myself almost never
> using it) required SVN version of madwifi (dunno if now the stable
> version works, will check when upgrading kernel), and so far attempting
> to set power saving on my wireless card fails.
> 
> The Macbook Pro also has a nvidia video card. The nvidia drivers work
> quite well (apart from some issues with external dvi resolution), but as
> far as I know, on it the "Powermizer" feature is somehow disabled. :(
> 
> I guess both things combined can explain at least a significant quantity
> of the power drain. Suggestions are much welcome, I hate the reduced
> battery power.
> 
> m.


1. Use laptop-mode if you don't do it by now. Really nice even without
its delayed disk write feature.

2. Displays are by far the biggest energy consumers. Lower its
brightness as far as possible. Some laptops even allow you to switch its
backlight off - very nice if you are outdoor.

3. Use the powersave-governor. If you really need the additional power
ondemand offers, try the conservative-governor. It increases the clock
rate slower than ondemand and might stop it from jumping too fast too
high.

4. Try sys-power/powertop. It shows you processes creating a lot up
wakeups for the CPU. It also gives you tips on your kernel config.

5. Sometimes a BIOS update helps...

Hope this helps. 

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