# Laptop optimization

## Radhek

Hi all,

I initiated a debate on the gentoo-user mailing-list about laptop optimization. The sinews of war is to get the right balance between performance and power consumption. Follows a summary of what we said :

 Filesystem :

I pointed out that using a journalled filesystem might prove power consuming, so ext2 should be recommended. However Timo Boettcher pointed out that this might be a mistake since laptop are more prone to filesystem errors since they are on the move and can run out of batteries. He suggests ext3. MAL added that ext3 can be set to commit the journal less frequently, the default being 5 seconds. In the end, it seemed that everyone agreed on the following :

The right filesystem to use is reiserfs, since tests have proven that it does not alter battery life. No one should use XFS due to extensive caching.

 Which WM ?

Contrary to what one may expect, people seemed to agree that any *Box desktop is preferable to gnome or kde, as far as power consumption is concerned.

 Which kernel ?

gentoo-sources and gs-sources come on top of the list. However, I would personnaly recommend gs-sources since they include the CPU frequency scaling options. Do not forget to enable vendor specific options !

ACPI or APM ?

The vast majority of the posts concluded that one should use ACPI if it is available and supports the laptop.

Framebuffer ?

Framebuffer should be used as a replacement to X every time it is possible. It can be enabled in the kernel. Of course anyone should avoid white background images (bootsplash) on the console, since backlight consumes a tremendous amount of battery.

Here it is, Comments are very welcome !

Radhek

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## xcable

Im an electrical engineer and I work with direct sunlight readably LCDs (extremely bright backlight).  A color TFT LCD does not produce light, so a florescent backlight must be used.  In a laptop the backlight is either on or off (some advanced laptops do have backlight brightness control, but they are few).  Using a black or dark background will not save any significant amount of energy.  The only energy you might same is the difference in activation the transistors to produce the red, green, and blue pixels to turn on all the way (white) -vs- not activating the transistors at all (black).

heath holcomb

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## hulk2nd

i would use the ac-sources because they are optimized for laptops, as far as i know. for example, the current kernel already supports the pentium m (centrino) enhanced speedstep, the latest acpi patches and several other things

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## xcable

ac-sources?

Alan Cox's kernel tree?  I was not aware that they were optimized for laptops.  I thought that was just his development tree geared to more advanced drivers and features that are not included in the main tree.

heath holcomb

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## hulk2nd

or you use the laptopkernel patch http://savannah.nongnu.org/projects/laptopkernel/. but i sadly never made them working    :Confused: 

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## helmers

I would really like to know what the benefit is from using ACPI instead of APM, does the different CPU states really mean more saved power?

Also, for Gentoo I'll recommend using "-Os" when compiling, to create executables with the smallest memory print. And live without swap, as that makes my HD spin up from time to time. I mount swap only when needed, and this is a 128MB laptop.

Finally, if you want a "desktop", use XFCE4, it is a slimmed-down version of GNOME 2, with just as good looks. Finally, I would like to say that memory is rarely a problem. My 128MB laptop runs GNOME 2(with nautilus), PAN, Evolution and Galeon with several tabs, and it still uses around 25MB for caching.

But I can second the ReiserFS recommendation, as it is much faster, it seems to do write-caching well, and it is very noticable on a slow laptop HD.   :Wink: 

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