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. Acer B286HK: A 28-inch UHD LED 4K Monitor For As Low As $350
  2. Intel Xeon E5-1680 v3 & E5-2687W v3 Compared To The Core i7 5960X On Linux
  3. Intel 120GB 530 Series SSD Linux Performance
  4. Btrfs/EXT4/XFS/F2FS RAID 0/1/5/6/10 Linux Benchmarks On Four SSDs
Latest Linux Articles
  1. Mesa Git Yields Performance Improvements For Newer AMD GPUs
  2. Apple OS X 10.10 vs. Ubuntu 14.10 Performance
  3. Mesa 10.5-devel Brings Some Intel Haswell HD Graphics Changes Over Mesa 10.3
  4. NVIDIA vs. Nouveau Drivers With Linux 3.18 + Mesa 10.4-devel
Latest Linux News
  1. GenodeOS 14.11 Now Supports Intel's Wireless Hardware
  2. Jolla Tablet Could Have Upgrades For MicroSDHC, Split Screen, 3.5G
  3. Intel Has Last Round Of DRM Changes For Linux 3.19, Starts Dropping DRI1/UMS
  4. Fedora 21 Release Candidate 1 Awaits Your Testing
  5. GCC 5 Adds Support For ARM's Cortex-A17
  6. KWayland Server Component Coming For KDE Plasma 5.2
  7. NVIDIA Posts Tegra Gallium3D Patch For K1+ Support
  8. Ubuntu 14.10 MacBook Air Tests With Linux 3.18, Mesa 10.5
  9. AMD Richland APU Support Added To Coreboot
  10. 2014 Holiday Shopping Reminder, Happy Thanksgiving
Latest Forum Discussions
  1. Aliens vs predator for Linux
  2. Updated and Optimized Ubuntu Free Graphics Drivers
  3. Hurrican SDL Port
  4. Roadmap to Catalyst 14.10 ?
  5. how to configure module phoromatic ?
  6. PulseAudio 6.0 Is Coming & Other Linux Audio Plans For The Future
  7. Debian Developer Resigns From The Systemd Maintainership Team
  8. Cant get working Kaveri APU - A10-7850k