For laptop users and data center administrators, power consumption is an important issue. Intel recently released a cool, top-like utility called PowerTOP, which can help you track down processes which are consuming the most power on your machine.

When your CPU isn’t executing intructions, it enters an idle mode and consumes far less energy. Any program that keeps the CPU from entering this idle state will cause your machine to consume more power, regardless of how processor intensive the process is. PowerTOP monitors your CPU to determine how many of these “wake up” events occur, and will display the top offenders for you.

Also of note is the new tickless-idle feature in the 2.6.21-rc1 kernel:

The Linux 2.6.21 kernel introduces the so called tickless-idle
feature. This feature allows the processor to be really idle for long
periods of time, rather than having to wake up every millisecond for
the timer tick.

So, if you want to tune your Linux box for ultimate power efficiency, enable the tickless-idle feature in your kernel, grab PowerTOP, and start locating applications or drivers that aren’t working as effieciently as they should be.