cpudyn controls the speed in Intel SpeedStep, Pentium 4 Mobile, AMD Powernow, PowerPC, Crusoe LongRun machines with the cpufreq compiled in the kernel, or with machines that support ACPI throtling. It saves battery, lowers temperature, and can put the computer disks in standby mode if a given period has passed without any I/O operation. It works well even with journaled file systems such as Ext3, XFS, or ReiserFS. Even supports the new interface for kernels 2.6.x