Intel aims to cut Linux power usage

Intel has launched a green Linux project — "LessWatts.org" — designed to reduce the power consumption of Linux servers and PCs.

LessWatts.org was launched at the Intel Developer Forum last week by Renee James, vice president and general manager of Intel's Software and Solutions Group. The website features tips and utilities for reducing power consumption, including the PowerTop utility, which spots and restrains over-active software from waking the processor up from sleep state without good reason.

Utilising Intel's fixes can trim about 10 watts of power consumption off a modern dual-processor server, said Dirk Hohndel, chief technologist of Intel's Open-Source Technology Center. This has further benefits, says Intel, because every watt of server energy saved cuts another 1.3 watts from air conditioning. On mobile Linux devices, LessWatts.org promises longer battery life.

For instance, a current laptop running Red Hat's Fedora 7 uses about 21 watts. "If you apply six little changes we propose, that same laptop takes 15.5 watts," Hohndel said. "You have just added more than an hour to your battery runtime."

Processors can be made more efficient if they operate in quick bursts followed by idle periods, so LessWatts.org proposes a "race-to-idle" mentality for the Linux scheduler. Network cards, on the other hand, use less power if they operate at a lower speed, saving about two watts if they drop from gigabit speeds to 100Mbps.

LessWatts.org also suggests compressing data in graphics-processor communications, so less power is used by the memory interface. It takes thousandths of a watt to decompress data, but half a watt can be saved in the memory interface, Hohndel said. Some high-level software is simply hyperactive. For instance, the Linux sound mixer can wake the processor 50 times a second to check whether someone has altered the volume controller — even on servers that only have basic sound chips and the volume set to zero.