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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