Using CentOS 4.1 as the Operating System on my laptop for all my work, I’ve been able to throttle down my CPU when running on battery power to extend my battery life, much like the modes that Windoze provides.

$ echo 5 > /proc/acpi/processor/CPU0/throttling

If you want to go back up again:

$ echo 0 > /proc/acpi/processor/CPU0/throttling

Not to be thrown, the output of this file looks like:

[root@lamda ~]# cat /proc/acpi/processor/CPU0/throttling
state count:             8
active state:            T7
states:
    T0:                  00%
    T1:                  12%
    T2:                  25%
    T3:                  37%
    T4:                  50%
   *T5:                  62%
    T6:                  75%
    T7:                  87%