Since Friday there's been a number of Phoronix articles about a very bad power regression in the mainline Linux kernel, which is widespread, Ubuntu 11.04 is one of the affected distributions, and has been deemed a bug of high importance. This yet-to-be-resolved issue is affected Linux 2.6.38 and 2.6.39 kernels and for many desktop and notebook systems is causing a 10~30% increase in power consumption. Nevertheless, this is not the only major outstanding power regression in the mainline tree, there is another dramatic regression now spotted as well that is yet-to-be-fixed.

Since the discovery last week of the Linux 2.6.38 and 2.6.39 kernels going through excessive amounts of power compared to 2.6.37 and earlier, each day and practically all day since that time has been working on Linux power consumption tests. Power consumption benchmarks are not normally an area we focus on nor do many others, but since the inadvertent discovery of it when testing out the power consumption of past Ubuntu Linux releases, a lot of time has spent investigating the matter within the kernel. In order to do such, there's been continued improvements to the Phoronix Test Suite, Phoromatic, OpenBenchmarking.org, and the PTS Commercial scripts for better enhancing the power testing, more improvements to multi-point automated regression bisecting, etc. The Phoronix Test Suite has already been able to monitor and log the power consumption (along with temperatures, fan speeds, I/O wait, system load, etc) for any test profile/suite being run by using the system monitor module, but now there is more. Thanks to working on that Easter weekend, coming to fruition because of that today is the discovery of another regression while still working on finding the first commit causing a power regression.

rest here