Longer Laptop Battery Life under Linux
ThinkingInBinary writes "Want easier power management and better battery life on your Linux laptop? Try powermgr, a daemon that automatically (or manually, if you choose) switches your system between power "profiles". It has support for ACPI (of course) as well as Asus, Dell, IBM, Omnibook, and Toshiba extensions. It can control CPU governor, screen brightness, wireless card, laptop mode (via services), runlevel, services, and more, and can switch based on AC adapter and battery state, load average, temperature, running processes, and more. Tests indicate that it can prolong battery life by 20 minutes to almost two hours, depending on what the system is doing. Try it out!"
Why just the emphasis on laptops?
Wasted energy from a wall outlet is still wasted energy. Transferring the energy-saving mindset to the desktop would likely have some positive results, especially for all those people using a 3GHz machine to play Freecell and send a few emails.
It still has some issues with it being set to run or not. I run this on my ubuntu setup for my IBM T43 and if you unplug the laptop and plug it back in, it thinks it is still unplugged. Thus, the screen turns off after set ammount of time, etc. etc. (which I prefer to be always on if it's plugged in). And changing it's settings are buggy.
It does get me over 3 hours of battery life, however, with my centrino processor which I really can't complain about. And with full brightness I still get 2 hours so long as I'm not doing any gaming or anything (DVD = over 2 hours low brightness)
I've recently went through this, but not for a laptop, but a Pentium 100 with 64 MB, running FC3 acting as an ADSL router and Subversion server (!).
Essentially I activated the "laptop mode" kernel variable (/proc/sys/vm/laptop_mode or similar), set the hard drives to spin down after 30 seconds using hdparm, killed all the unneeded services, and cleaned up the crontab; sa in particular was causing the hard disks to spin up every 10 minutes, which I wanted to avoid. This took me a while to figure out.
Now I have a very silent, very cool (as in temperature) "server".
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