A new patch is promising to addresses power regression problems that have cropped up in recent versions of the Linux operating system. According to PCWorld, version 2.6.38 or later of the Linux kernel is affected by the problem, which results in increased power consumption that is evident even on a modern Sandy Bridge laptop. Upgrading from Linux 2.6.37 to 2.6.38 caused a jump of 9 watts in average power consumption, with further increases in average consumption observed in subsequent versions of the kernel.

The problem affects both laptops and desktops.

The key to the problem appears related to how the PCI Express Active State Power Management (ASPM) of many systems was being frequently disabled in circumstances when it should not be. Red Hat engineer Matthew Garrett used 60 lines of code to modify ASPM behavior and rectify the problem.

Ironically, the dearth of public documentation relating to how ASPM works means the inspiration for a fix came by observing how the Windows operating system handles the PCIe bus interface. The patch is unlikely to appear in the mainline Linux kernel until the 3.3 release however, though it could still make it into the Linux 3.2 kernel package. Do note that a reboot will be required after application of the patch.

For more:
- check out this article at PCWorld

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