understanding acpi

Oliver Henriot
2006-11-30T10:59:14Z

Hi all list subscribers,

I'm looking for info on how acpi functions in order to get it to work
the best possible on my computer. It's a Sony laptop (vaio vgn-sz3xp/c,
core2duo) running Debian Etch. In particular, I'm looking for ways to
reduce thermal dissipation from the CPU as much as possible, in order to
queep the machine as quiet as possible. From the various docs I've read,
so far I seem to understand that C-states is the way to go, throttling
being probably not very efficient.

When I'm running on batteries, C3 state is active (as shown by cat
/prc/acpi/processor/CPU0/power) and is the main state, whereas when I'm
running on mains, C3 disappears and only C1 and C2 remain.

My question are : wouldn't it be better if I could use C3 even when on
mains. Wouldn't it be even better with C4? As suggested by "Why My Cx
Power State Is Not Used" I tried unloading various modules (e.g. those
concerning usb but I got stuck with usbcore which refused to unload
despite nothing usb being connected) without any success. Being
relatively new to GNU/Linux, I'm a bit stuck here and don't know where
to look or what to make of this.

Any help would be gladly welcome.

Cheers,

Oliver