Longer Laptop Battery Life under Linux 45
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!"
Re:Not Just Laptops (Score:5, Informative)
In addition, you can already do things such as underclock video cards, and disable certain boards such as NICs and sound cards via software. I can't see why it couldn't be added to a power management function.
You are correct about the flatpanel one AFAIK.
Not only laptops (Score:5, Informative)
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".
Re:Not only laptops (Score:3, Informative)
You better have good backups. Desktop hard disks aren't designed to spin up/down that often. Remember each spin up and down means contact and rubbing on the head surface.
I'd be suprised if the hd lasted more then a year.
Laptop hd's are (hopefully) designed with loading technology that move the heads aways from any contact at all with the surface. They do that a: for spin up/down and also b: so you minimize the risk of a head slap, what with laptops moving so much.
Also, with a 3.5inch disk, the energy used just to spin it up is more then the energy used in letting it spin. Approxmiately a spin up costs as much as 30 seconds of spin time. 2.5 inch disks are much lighter, and they are designed to read data before it's fully spun up.
Re:Not only laptops (Score:3, Informative)
Every time you turn it on and off. Really. It rubs on the surface until the platter spins fast enough to provide lift (like a wing) for the head. That's why I keep mine on 24x7. IBM patented a head load unload safety ramp to stop this from happening. But as far as I know no one else uses it.
"In my experience, that usually creates a truly frightening sound and an extreme amount of data loss..."
No, the noise (if you hear one) is bearings that died.
Also, the hd parks it's heads before letting them touch the surface, so they touch a special area of the platter that has no data on it.
Re:Not so great... (Score:2, Informative)
This is probably due to a timing issue where powermgr is still checking the system when you plug it back in the second time; I'll take a look at it. Please post bug reports on the SF.net tracker or, if you don't have a SF.net login, email them to thomastuttle(at)users.sourceforge.net. I'd be glad to try to fix any problems you have.
Re:Not Just Laptops (Score:3, Informative)
I'd be glad to add features to do such things to powermgr; just tell me what package is required and the command to execute, and I'll add support for it. Personally, I only have an Asus laptop, so the Dell, IBM, Omnibook, and Toshiba features were mostly added by reading the man pages for the respective tools. Thus I would need a good description of how to activate a feature before I can implement it.
Once you know how, post it in the SF.net tracker, or, if you can't, email it to me at thomastuttle(at)users.sourceforge.net.