No matter what you do in hardware to save power, software is always there to trip you up. One of the complaints about the early smartphones from the chipmakers was that the operating system vendors did little to active the power-saving features in their chipsets – it took time for them to use the hooks that were present all along. Some recent benchmarks from the world of Linux show how sensitive to minor kernel-level code changes power consumption can be. Posting at Phoronix, Michael Larabel performed comparisons on several versions of the Ubuntu distribution. He found that, rather than going down, the latest versions show an increase in average power consumption, even when the kernel is idling.
The culprit isn’t clear yet but suspicion has fallen on memory-management code and the clock timer interrupt – which may be activating more frequently in Ubuntu 11.04 compared with previous versions. Whatever the cause, minor changes in recent subreleases of the 2.6 Linux kernel used in Ubuntu 11 seems to be pushing up power consumption by 10 to 30 per cent.
