Public bug reported: I would like to report what myself and several others believe to be a serious bug affecting all Linux kernels 3.0 and up, and none below 3.0 (2.6.x and lower). I tested this using .deb kernel packages for Ubuntu 11.10.
One-sentence description: On certain hardware, the 3.x series kernels drain a considerable amount more power than the 2.6-series kernels, up to 40% more, even when idle. The specific hardware I have personally tested is a Lenovo ThinkPad X220 with an Intel SandyBridge i7 2620M processor. We think that this bug is POSSIBLY specific to this processor, or family of processors, commonly used in notebooks. A complete thread of mine and others' results, evidence, and troubleshooting process is located at: http://ubuntuforums.org/showthread.php?t=1822629 We have tried several different 3.0 and 3.1-series kernels, all with the same problems. One part of the problem was that the following (revealed by powertop) was causing excessive processor wakeups compared to the 2.6-series kernels: "[Rescheduling interrupts] <kernel IPI>" Someone much more advanced than I figured out how to eliminate this problem and recompiled the kernel (which he posted in the thread I linked to previously), but power usage is still improved only slightly, nowhere near kernel 2.6 levels. There is a lot more information I could give you here, but all of it is contained within the thread I linked to. If you have any specific questions, I will answer as quickly as possible. ** Affects: ubuntu Importance: Undecided Status: New ** Summary changed: - Huge power regression from kernel 2.6.x on Sandy Bridge laptops + Huge power regression in kernel 3.x on Sandy Bridge laptops -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/834037 Title: Huge power regression in kernel 3.x on Sandy Bridge laptops To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/834037/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
