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ACPI

Power Management

This page covers ACPI configuration, and partially duplicates info covered elsewhere.

The ACPI Daemon

You'll need the ACPI Daemon, and then add the appropriate script configurations. Additional ACPI scripts are available. This will allow handling of the following:

• Lid Opening/Closing
• Power Button press
• AC Adapter/Battery
• Processor

Battery Info

Getting information about the battery:

 > cat /proc/acpi/battery/BAT0/info
 > 

Maximum Battery Life

Reducing power consumption reduces the heat produced - which in turn cuts down on fan noise, which is a good thing (it is audible enough for me to get irritated by unless I have music on). Standard CPU-core temperature used to be around 60'C - I have since managed to get this reduced to about 50'C, just by tweaking the vanilla kernel.

Reducing power consumption extends battery life whilst mobile, and extends the life of the laptop.

• CPU - Reduce clock, reduce voltage, optimise kernel, pre-link binaries.
• Hard Disk - can we slow a 7200rpm drive down? Are there any tweaks?
• Turn off screen when not in use.
• What else?

Thanks to Intel, we have PowerTOP, a utility which monitors CPU interrupt activity, we can begin to tweak. It's quite surprising just how (in)efficient your kernel can be. My kernel for the last year has been running at ??? Wakeups-from-idle per second. It is now at 390wps under Xwindows, and 30wps under the console.

Suspend

This can be slightly confusing, as there are several implementations of similar functionality. Some options require a kernel patch. There is a summary of suspend implementations available, which tries to list the differences between them.

Suspend to RAM

Not done yet.

Suspend to Disk

Guess what? Nope - I've not sorted this, either!