cpufrequtils 002 review

cpufrequtils project consists of a library which offers an unified access method for userspace tools and programs to the CPU frequenc

License: GPL (GNU General Public License) File size: 36K Developer: Dominik Broodwski

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cpufrequtils project consists of a library which offers an unified access method for userspace tools and programs to the CPU frequency and voltage scaling (cpufreq) subsystem in the Linux kernel, the "cpufreq-info" and "cpufreq-set" tools to determine and set cpufreq settings, and debug tools helpful if frequency scaling doesn't work as expected.

"libcpufreq" is a library which offers a unified access method for userspace tools and programs to the cpufreq core and drivers in the Linux kernel.

This allows for code reduction in userspace tools, a clean implementation of the interaction to the cpufreq core, and support for both the sysfs and proc interfaces [depending on configuration, see below].

"cpufreq-info" determines current cpufreq settings, and provides useful
debug information to users and bug-hunters.

"cpufreq-set" allows to set a specific frequency and/or new cpufreq policies
without having to type "/sys/devices/system/cpu/cpu0/cpufreq" all the time.

Installation:

./configure && make
su
make install

should suffice on most systems. It builds default libcpufreq, cpufreq-set and cpufreq-info files and installs them in /usr/local/lib and /usr/local/bin, respectively. Due to the autotoolization by Mattia Dongili the standard options to make and make install, like "--prefix=/usr", can be passed and (should) work correctly.

Options and dependencies:

./configure by default enables the sysfs interface, but disables the

deprecated /proc interface to the cpufreq core in the Linux kernel. For the sysfs interface to build and work correctly, you need "libsysfs", which is part of the "sysfsutils" package. Current requirement is sysfsutils-1.0.0 or later.

To disable the sysfs interface, pass the option "--disable-sysfs" to ./configure.

To enable the (deprecated) /proc interface support, pass the option "--enable-proc" to ./configure.

What's New in This Release:
This release includes a couple of build and Makefile fixes and also a patch which causes cpufrequtils to always set the maximum frequency before the minimum frequency on a policy change, as the kernel expects.