On 01/03/2011 01:29 PM, Steven Haigh wrote:
What I don't understand is that if the CPU supports ACPI, the mainboard 
supports ACPI, why can't we throttle the CPU using ACPI?

As I have mentioned several most likely cause is the BIOS either not configured to do so or unable to do so..

INTEL has some processors that report they can while en fact they cant.

To find that out you would have to dig deep into Intel docs.

Look for the Highest Frequency Mode (HFM) and Lowest Frequency Mode (LFM) in those documents for your processors and if it says that the processor in question operates at same core frequency in HFM and LFM then it cant but I dont think you need to worry about that since you mentioned that it did switch cpufrequency when run with GOVERNOR=userspace.

JBG