Another Major Linux Power Regression Spotted
Written by Michael Larabel in Operating Systems on 25 April 2011. Page 2 of 4. 38 Comments

The hardware for the ThinkPad R52 used in this article is an Intel Pentium M 1.86GHz, 2GB of system RAM, 80GB Hitachi IDE HDD, and ATI Mobility Radeon X300 graphics. Besides the vanilla kernels, the Ubuntu 8.04.4 LTS user-space was used with GNOME 2.22.3, X Server 1.4.0.90, xf86-video-ati 4.3.0, Mesa 7.0.3-rc2, GCC 4.2.4, and the EXT3 file-system.

The first graph is simply showing the Ubuntu Hardy Heron desktop idling for a period of two minutes before any tests are carried out. In this first test, it shows that even while idling from the Linux 2.6.34 to 2.6.35 kernels there is a spike in power consumption with the average going from 16.7 Watts to 20.6 Watts. With the Linux 2.6.38 kernel on Ubuntu 8.04.4 LTS it goes up to 21.9 Watts, which also shows that the 2.6.38 regression isn't related to any user-space interaction problems in Natty or Maverick where the focused kernel tests were carried out last week.

In the second test, it is the notebook idling, and then idling with the display flipped off via DPMS, and then flipped back on again for MPlayer to run a brief video test. The power consumption results during the video playback are mixed, but the overall average still highlights the 2.5.35 and 2.6.38 kernels vastly setting back Linux power management for the ThinkPad notebook.

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