New cpufreq framework and drivers

Nate Lawson nate at root.org
Tue Feb 1 08:58:40 PST 2005


cpufreq is a framework for individual drivers to provide cpu power 
management and an interface for the user and other parts of the kernel 
to access that framework.  Hardware drivers are of two types, absolute 
and relative.  SpeedStep, Powernow, etc. are absolute drivers in that 
they set the cpu's base frequency.  ACPI throttling, Longrun, etc. are 
relative drivers that reduce the processor's clock to a fraction of its 
current base (i.e., they have an additive effect.)  The first release 
version of cpufreq only supports absolute drivers but the interface and 
framework have been tested with relative drivers.  Existing relative 
drivers will continue to work with their current interfaces.

Below is the first patch of cpufreq for wider testing.  It has the 
framework, cpu pseudodriver updates, and two hardware drivers -- ACPI 
performance states and SpeedStep-ICH.  It has had a lot of testing on 
supported hardware but needs wider testing before importing.  Other 
hardware drivers can be quickly ported to this interface, and I'm happy 
to assist their maintainers.

http://www.root.org/~nate/freebsd/cpufreq.diff

-- 
Nate


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