- CPUSpeed

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  • October 8, 2008 - CPUSpeed 1.5 released!

What is it?

CPUFreq is a Linux kernel subsystem which allows the clock speed of mobile CPUs (most often found in laptop computers) to be explicitly set. CPUSpeed dynamically controls CPUFreq, slowing down the CPU to conserve power and reduce heat when the system is idle, on battery power or overheating, and speeding up the CPU when the system is busy and more processing power is needed. Using CPUSpeed can significantly increase a laptop computer's battery life and significantly reduce the heat it generates while still allowing your system to perform at top speed when you need it.

Features in the current version

  • Dynamically adjusts CPU speed and voltage based on demand for CPU (idle/work ratio threshold is user-configurable)
  • Automatically detects available processor speeds
  • For normal operation, no configuration or options are necessary. Just run it!
  • Full multiprocessor and multi-core support. Automatically determines which cores need to be controlled together or separately (configurable)
  • Configurable minimum and maximum allowed speeds
  • Can reduce CPU speed and voltage if AC power is disconnected from the computer (requires ACPI)
  • Can maximize CPU speed if AC power is connected to the computer (requires ACPI)
  • Can reduce CPU speed and voltage if CPU temperature gets too high (Requires ACPI, temperature is user-configurable)
  • Can be told to lock CPU at minimum or maximum frequency via signals
  • "nice()'d" processes and those waiting for I/O will not increase CPU speed
  • Polling interval for CPUs, temperature and AC adapter configurable separately
  • Crash-proof frequency switching even if you have an outdated version of CPUFreq and a very temperamental CPU (some AMD mobile Athlons in particular)
  • Handles strange processors with lots of little speed steps
  • More that I am forgetting...

What you need

In order to use CPUSpeed you will need the following:
  1. A CPU capable of scaling its frequency and / or voltage. Many modern mobile CPUs found in laptop computers can do this, including the Mobile AMD Athlon 64, Mobile AMD Athlon XP-M, the Intel Pentium 4M, the Intel Centrino, Mobile AMD Sempron, Mobile AMD Turion 64 and the Transmeta Crusoe. (Note that some laptop computers may actually have desktop CPUs which are not capable of scaling. These CPUs cannot be used and should be avoided when purchasing a new laptop computer.)
  2. A version of the Linux kernel that supports CPU frequency / voltage scaling (CPUFreq) with both
    1. Support for you particular type of CPU either compiled in or available as a module
    2. Support for the "userspace" CPUFreq governor


CPUSpeed is released under the GNU General Public License version 2 (or if you wish any later version). This license allows you to use, copy, distribute and modify the software with very few restrictions. The full text of the license may be found here.

Where to get it

The latest release of CPUSpeed is version 1.5. This and and older versions can be downloaded here.

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