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Getting Better Battery Life w/ Linux?
Nuclear Elephant asks: "After a little hacking, Linux has been running great on my Thinkpad T30 for about a year now. I can talk to my cellphone and bluetooth devices, do all kinds of neat hacking on wireless, and just about everything you'd expect to be able to do from a Windows machine, except make the battery last. Even after the standard optimizations (like cpufreq, laptop_mode, brightness, turning off useless processes, etc.) my battery still only lasts about an hour running under Linux as opposed to 2 1/2 hours in Windows. Has anybody come up with some innovative battery conservation ideas for Linux? It seems to be the only thing lacking in this fine operating system." What kernel options might one look into, for saving laptop battery power? Also, what desktop settings (both for Gnome and KDE) would work best, for this situation?
If you use and unload kernel modules, wireless NIC, sound card, hotplug, usb etc etc... your laptop should consume a bit less power, also look to see if your laptop supports processor frequency scaleing
Have the harddisk spin down (e.g., hdparm, noflushd), dim the screen, lower the processor speed (e.g., longrun). In general, it shouldn't take a lot of effort to get similar battery life using Windows and Linux.
If you buy your machine from a vendor that supports and pre-installs Linux (e.g., emperorlinux.com), they probably will take care of the necessary configuration for you.
Since you have a Thinkpad, you should download and install tpctl. It comes with a daemon called apmiser that controls power use according to CPU usage.
Don't forget to decrease the brightness and contrast of your display. I found this can add an extra half an hour or so to your battery life.
And, as was hinted at by others, take off anything that will cause your processor to do more work than you need. This means removing big GUI's, and use basic software (like anything but Gnome and KDE, Firefox instead of Mozilla Suite, Mutt instead of Evolution, etc.)
Those features are probably not supported. There are people working on them, but at best you'll have to compile your own copy of XFree86. I only know this because I spent a couple hours yesterday getting DRI to work on my T30. I read a lot of docs.
If tits were wings it'd be flying around.
There is the "Battery Powered Mini-HOWTO" up on the Linux Documentation Project site: http://www.tldp.org/HOWTO/Battery-Powered/index.ht ml
Of course, you probably looked there first before you asked Slashdot :)
Seriously, read the section on syslogd(8). In addition to their suggestions, we have also setup a central log server which allows logging to only go over the network, and not to the local disk at all.
If you are in a LAN (or wireless) environment, you might want to consider that although the wireless might cost you more powering the NIC than it would hitting the disk (after you disabled syncing).
You could use a loger like metalog which caches writes to reduce the amount of hard drive use. Also setting the noatime option in fstab will reduce writes to do the disk when you are browsing directories. This will not help the fact that the drives always spinning though. To avoid that you would pretty much need to turn of logging which may not be a good idea. Anyway that's just my .02
One of the single best things you can do is enable ACPI support, which enables higher levels of CPU power saving when idle. This gives me about half an hour of extra battery power, but suspend support is still somewhat flaky.
Given that the default fan thresholds of the 8200 are VERY aggressive w.r.t. power management (i.e. they run the CPU *damn hot* and you should NOT be slowing down the fans compared to the BIOS defaults), I don't think this is the reason for your long battery life with the 8200.
But I can confirm that my battery life with my I8200 is comparable to, if not better than, under Windows.
Power management features I use:
cpufreq (Both speedstep-ich and p4-clockmod as modules - Load speedstep-ich, set the "powersave" governor to step down the voltage/speed, then load p4-clockmod to drop the clock speed even more. I've been running my P4-M 1.7 at 600 MHz lately, it's more than responsive enough for AIM and web browsing.)
nvclock (Does not support mobile chipsets out of the box, but I disabled the code that causes nvclock to not touch mobile chipsets and it works fine on my GeForce 4 Go 440. I'm assuming the devs of nvclock disabled this because it's an overclocking tool and overclocking mobile GPUs is a bad idea, they forgot that mobile users might actually want to UNDERCLOCK their GPUs...)
Get LOTS of memory. Enough to allow you to disable swap. If you have swap enabled, it seems that even with an idle machine, it'll page stuff in/out just enough to FUBAR any attempts to make the HD sleep.
retrorocket.o not found, launch anyway?