Power Saving

[Andrew]

Hi,

I was wondering what the "correct" way was meant to be to implement "CPU
throttling" under FreeBSD 5. At boot I get:

acpi_cpu: throttling enabled, 2 steps (100% to 50.0%), currently 100.0%

Setting hw.acpi.cpu.performance_speed to 1 seems to slow the CPU down (the
percentages shown by top all increase).

I want the CPU to be automatically throttled when the system is idle. I
could write a daemon to poll the CPU usage every now and then and set the
sysctl as needed but I thought there may be another way - perhaps there
are hooks in the scheduler/idle loop for this sort of thing?

Also, how do I get the HD to slow down? I have an IBM deskstar that lcaims
to support running at half speed and I'd like that to happen when the disk
hasn't been accessed in a while...

Thanks,

Andrew