This thread has been enlightening, to say the least. But not super encouraging. What I'm getting from this thread is that suspend to ram is possible on some laptops. But it may require some assembly. Furthermore from what Thinkpad owners have told me (this extends to all Linux laptops from what I can see) that battery life is well below Windows XP on the same machine. 3 hours is considered "good" for a T61p with a 9 cell battery. So for a variety of reasons, many of which would seem to be beyond our control as Linux hackers, power management on Linux just isn't there yet. This point of view, according to a slashdot comment criticizing me, is FUD, but oh well.
I recently started playing a bit with Powertop[1]. For fedora or ubuntu users I'm sure it's in the standard repositories. Using powertop is very interesting. I recommend that anyone with Linux on their laptop install it and see what it says. It will track power usage (when not on AC power), CPU states, interrupts and so forth. On a desktop machine you'll not get power usage statistics, but you will get interrupts per second and the cpu states. My AMD desktop machine was very interesting. The NVidia binary drive woke up the CPU between 60 and 100 times a second. On a laptop this would really affect battery life. Also my CPU never once reached the "C3" state, which on a laptop is where your cpu should be spending 80% of its time, in battery conservation mode. So obviously my desktop machine is a power hog. If any of you are running the NVIDIA drivers on a laptop, there is an xorg.conf setting that you can use to disable the VBLANK interrupt, except when it's demanded. This reduces the number of CPU wake-ups pretty dramatically. Also powertop can recommend a number of things, like setting the sleep (as in idle) mode on the usb drivers, the audio drivers, etc. Someone claimed that they were able to get a Gnome desktop down to 5 wake-ups per second. Judging from my own Gnome desktop they must have disabled every little thing, but still. Anyway, I appreciate the feedback. Looks like I'll be holding off on my decision for a while yet. Leopard will run on my PB 12", so we'll see how that goes for now. Michael [1] http://www.lesswatts.org/projects/powertop/ /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
