The Power Capping Framework and RAPL driver were combined today into a new patch series by Srinivas Pandruvada. For modern hardware that supports such capabilities, this code is about power monitoring of individual devices, support for setting power limits on individual devices to avoid reaching a maximum system power level, maximizing performance while staying below a certain power limit, and dynamically controlling and re-budgeting power use.
The RAPL (Running Average Power Limit) driver takes advantage of the latest Intel CPUs for power capping different devices and are also hoping other vendors will implement similar hardware functionality. The Power Capping framework for the Linux kernel seeks to provide a uniform sysfs interface for exposing devices that can be power-capped and to provide a common API for Linux drivers.
This code has already been proposed before under an "RFC" flag but today's patches remove that tag and are going under a "v1" status -- it looks like this code may be ready for merging into the Linux 3.13 kernel. The patches can be found on the Linux kernel mailing list.