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A Proper Solution To The Linux ASPM Problem

Michael Larabel

Published on 11 November 2011
Written by Michael Larabel
Page 3 of 3 - 40 Comments

Migrating from the Linux 2.6.37 to 2.6.38 kernel caused the power consumption to go up by nine Watts due to this ASPM regression. This is an increase in power consumption by 36%. It works to set pcie_aspm=force on the ThinkPad notebook, but up through the latest Linux 3.2 kernel code as of today the regression still stood in its stock configuration. However, when applying Matthew's patch, the "out of the box" power performance finally returns to pre-2.6.38 levels!

Under graphics load the ASPM regression causes the Core i7 notebook to be burning through six more Watts (an increase of 14%) than when ASPM is active. When trying out today's ASPM patch, the power is back to the levels experienced on Linux 2.6.37. Hell yes!

The results from this ThinkPad notebook are similar to the several other notebooks I have tested the past few hours.

Since the Linux 3.2 kernel merge window closed earlier this week and this is a behavioral change rather than being just a simple fix or reverting the earlier commit, it might not see the mainline tree until the Linux 3.3 kernel. If it does not make it into 3.2, hopefully the patch will at least be carried into the Linux 3.2 kernel package for Ubuntu 12.04 LTS and other distributions.

The patch can be currently fetched from the kernel mailing list and it applied cleanly against today's Linus Git code for the 3.2 kernel head.

UPDATE: More ASPM kernel patches have been published.

That's one regression now addressed, with only several more power management issues left in the kernel...

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
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