Ubuntu 12.04 LTS Will Try For Intel RC6 By Default
Having RC6 in Ubuntu 12.04 LTS isn't resulting in any original work by Canonical/Ubuntu, but rather it was last week when Intel announced they believe they finally have RC6 support in shape and will be enabling it by default when it comes time for the Linux 3.4 kernel merge window. The kernel team is back-porting the patches to their Linux 3.2 kernel. What the patches did is just enable basic RC6 support by default for Sandy Bridge while only exposing the deep and deepest RC6 power-savings states via a kernel module parameter.
Read Intel Tries To Fix RC6 Support Once Again and Intel Flip-Flops Again: RC6 Disabled For Linux 3.2 for the scope of the situation. This has been a constant battle for Intel's open-source developers on Sandy Bridge, but at least for the next-generation Ivy Bridge hardware its more reliable.
RC6 is quite good since it allows bringing down the graphics core to consuming 0V when allowed and it's also capable of boosting the system's graphics performance, as Phoronix tests have shown. I also happen to have more RC6 benchmarks coming out in the next week or so, the tests are already done of normal RC6, deep RC6, and the deepest RC6 states, but right now is just sitting in the publishing queue. While this is focused on conserving battery power, RC6 also helps out on Intel desktops too.
The kernel team for Ubuntu enabled Sandy Bridge RC6 by default in the 3.2.0-17.26 Precise kernel. Their mailing list message mentions, "We have decided to post a widespread call for testing from Sandy Bridge owners running Ubuntu 12.04. We hope to capture data which supports the the claims of power saving improvements and therefore justify keeping these patches in the Ubuntu 12.04 kernel."