1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

Linux Kernel Power Consumption Is Lowered, But Regressions Remain

Michael Larabel

Published on 8 June 2011
Written by Michael Larabel
Page 1 of 1 - 20 Comments

As discovered by a Phoronix reader, there is a patch in the Linux 2.6.39.1 kernel that can partially improve the system's power performance. The patch by a Nokia engineer is entitled "cpuidle: menu: fixed wrapping timers at 4.294 seconds" and initial reports have said that it will lower the power consumption compared to the stock 2.6.39 kernel.

"Cpuidle menu governor is using u32 as a temporary datatype for storing nanosecond values which wrap around at 4.294 seconds. This causes errors in predicted sleep times resulting in higher than should be C state selection and increased power consumption. This also breaks cpuidle state residency statistics."

This patch was then brought up in LaunchPad Bug #760131, which is the Ubuntu bug report tracking this upstream kernel problem. Those that have tested this patch / the Linux 2.6.39.1 have reported their power consumption has dropped along with lower operating temperatures now that the CPUs are switching properly to their lower C-states and staying there. However, this does not address the complete Linux kernel problem.

A round of Phoronix power tests were carried out today to see the impact of the 2.6.39.1 kernel. While the power consumption on 2.6.39.1 is now lower than in the bugged Linux 2.6.38 release, it is still off. The Linux 2.6.39.1 power consumption is still elevated from its Linux 2.6.37 levels, which is the release before the big Linux kernel power regression. This suggests that this might not even be a fix for the real regression in the 2.6.38 merge window but rather just a power management improvement that is now landing. There is also at least one other Linux kernel power regression affecting a great number of systems. The average power consumption with the Linux 2.6.39.1 kernel is still up by an approximate 18~20% over older (Linux 2.6.34 era) kernels or over 22% for a system that's not affected by the Linux 2.6.35 power bug. While this 2.6.39.1 reduced power consumption is a nice improvement, there is still regressions left to bisect.

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 .
Latest Linux Hardware Reviews
  1. Even With Re-Clocking, Nouveau Remains Behind NVIDIA's Proprietary Linux Driver
  2. The Power Consumption & Efficiency Of Open-Source GPU Drivers
  3. AMD R600g/RadeonSI Performance On Linux 3.16 With Mesa 10.3-devel
  4. Intel Pentium G3258 On Linux
Latest Linux Articles
  1. AMD Catalyst 14.6 Does Slightly Better With APITest OpenGL Tests
  2. Updated Source Engine Benchmarks On The Latest AMD/NVIDIA Linux Drivers
  3. Nouveau vs. Radeon vs. Intel Tests On Linux 3.16, Mesa 10.3-devel
  4. KVM Benchmarks On Ubuntu 14.10
Latest Linux News
  1. Belkin's WRT54G Router Successor Is Crap On The Software Front So Far
  2. QEMU 2.1 Officially Released
  3. XBMC Is Being Renamed To "Kodi"
  4. SteamOS Beta 126 Better Handles XBMC
  5. Ubuntu 14.10 Alpha 2 Released
  6. KDE 4.14 Release Candidate Ships
  7. Drivers & Drama Dominated Linux Talk In July
  8. Fedora Assembles A Security Team
  9. AMD Launches The A10-7800, The 65 Watt Kaveri
  10. Builder: A New Development IDE Being Built For GNOME
Latest Forum Discussions
  1. AMD Launches The A10-7800, The 65 Watt Kaveri
  2. Grand Theft Auto Running On Direct3D Natively On Linux Shows Gallium3D Potential
  3. Updated and Optimized Ubuntu Free Graphics Drivers
  4. Linus Torvalds On GCC 4.9: Pure & Utter Crap
  5. Updated graphics drivers for Ubuntu 12.04 Precise LTS
  6. Debian + radeonsi
  7. AMD Publishes Open-Source Linux HSA Kernel Driver
  8. Open-source drivers on ATI R7 260X