nforce2 cpufreq

Andriy Gapon avg at icyb.net.ua
Thu May 25 08:03:51 PDT 2006


I've recently had a sudden urge to investigate power saving / cpu
throttling options for my desktop Athlon XP system.
It seems that the CPU itself does not provide any interfaces for that,
at least neither of acpi_perf/acpi_throttle/cpufreq seem to detect
anything interesting for them.
Or am I mistaken and doing something wrong ?

Anyway, my MB is based on nForce2 chipset and I found out that Linux has
 cpufreq-nforce2 module that works in their cpufreq framework:
http://www.hasw.net/linux/

It seems that that module works by using nForce2 PCI interface for
querying and changing FSB frequency. It also seems that the code is
rather simple and obvious in its logic (save for allegedly
reverse-engineered constants). Not sure though how easy it is to port
that to FreeBSD cpufreq framework.
But the question that I really would like to ask is the following: is it
a proper way to do cpufreq stuff by changing FSB frequency ? Would that
approach fit into our framework ? And finally, would it have any
positive temperature/power consumption effects ?

-- 
Andriy Gapon


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