The power consumption of the new kernel tulinux kernel has increased significantly.

Phoroni tested the overall system performance, power consumption, and Startup Performance of different versions of Ubuntu in his notebook. It was noted that the latest version of Ubuntu consumes more power under certain workloads, an average increase of 10%, up to 30%. Tests on the Linux kernel 2.6.35, 2.6.36, 2.6.37, 2.6.38, and 2.6.39 (Development version) show that the power consumption of the 2.6.38 kernel has increased significantly, and 2.6.39 has the same problem and has not been fixed yet. Bug reports on Ubuntu

Phoroni tested the overall system performance, power consumption, and Startup Performance of different versions of Ubuntu in his notebook. It was noted that the latest version of Ubuntu consumes more power under certain workloads, an average increase of 10%, up to 30%. Tests on Linux 2.6.35, 2.6.36, 2.6.37, 2.6.38, and 2.6.39 (Development) Kernels show that the power consumption of kernel 2.6.38 has increased significantly, and 2.6.39 has the same problem and has not been fixed yet. In the bug Reporting System of Ubuntu, users reported that the battery endurance of laptops running Ubuntu 11.04 was significantly reduced from 4 hours to around.

Test:

For those that follow my personal Twitter feed will know that for the past week I 've been closely testing Ubuntu 11.04 and all Ubuntu releases going back to Ubuntu 8.04 on your mobile devices in the office. the overall system performance, power consumption, and boot performance have been the principal targets. however, late this week I discovered a glaring regression: Ubuntu 11.04 is viciously going through power. compared to Ubuntu 10.10, the power consumption on Ubuntu 11.04 for mobile devices is up about 10% on average but under some workloads, I am seeing the power consumption up by nearly 30%. this is happening on Alibaba mobile systems spanning multiple generations of Intel CPUs and with Intel/ATI/NVIDIA graphics. this issue has been tracked down to a frightening kernel regression in the mainline tree that is still not addressed.

In the publishing queue for Monday morning is the main article for the full power consumption results with all of the tested mobile devices, more details, and of the Ubuntu releases going back to 8.04 hard. however, due to the severity of the regression, this afternoon I am putting out the key bits of information that has strate the regression. during the Linux 2.6.38 kernel development, a regression was introduced causing systems to burn through significantly more power. the below graph shows the battery power consumption of one of the Lenovo ThinkPad notebooks under the Linux 2.6.35, 2.6.36, 2.6.37, 2.6.38, and 2.6.39 (Git code as of 19 April 2011) kernels. unlike some of the other regressions to have been highlighted on Phoronix, this regression is still unfixed in Linux 2.6.39. on the particle system being talked about in the article today is the power consumption going up by 14%, which wowould lead to a noticeably shorter battery life.

This particle result is for the ThinkPad T60 with an Intel Core Duo and ATI Mobility Radeon graphics, but the power regression as spotted by the original Ubuntu 11.04 tests has been found on hardware going back to a vintage Pentium M notebook and also under Atom netbooks to a lesser extent. as far as what the above graph has strates, it is a composite overview showing the battery power consumption when the Ubuntu Linux system was idling followed by running the OpenArena game, and then running the OpenSSL benchmark to show a variety of workloads. the Linux 2.6.35/2.6.36/2.6.37 results are wrongly ally identical, but with 2.6.38 is where the regression strikes. as far as the Linux 2.6.39 results, it shows the regression still present. the Linux 2.6.39 results are slightly different from the 2.6.38 results likely because the Intel optimized WiFi adapter separately between and is currently borked/non-functional in this kernel on the ThinkPad T60. Below are the resbroults Ken down by test profile.

The above graph shows each of the kernel's power consumption when the system was doing nothing but idling in the GNOME desktop. between the Linux 2.6.37 and 2.6.38 vanilla kernels, the power consumption goes up by an average of 18% when just idling.

User feedback:

Bug Description
This is a regression moving from maverick-> natty. With the same sort of light interactive usage, Battery life has gone from ~ 4 hours to 2: 45 or so.
Running powertop shows the system in P-state "Turbo mode" 10-15% of the time. typically this was almost zero in maverick, 98 + % of the time maverick was in the lowest state.
Wakeups reported in the 5-600/s range where previusly (from memory) it was 200 ish. i915 driver is high on the list. This is irrespective of whether running unity or classic desktop.
ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-8-generic 2.6.38-8.42
Regression: Yes
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: amd64
ArecordDevices:
* *** List of CAPTURE Hardware Devices ****
Card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/Dev/snd/controlC0: james 2068 F... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
Card hw: 0 'intel '/'hda Intel at 0xf2620000 irq 47'
Mixer name: 'conexant CX20561 (Hermosa )'
Components: 'hda: 14f15051, 17aa20ff, 100'
Controls: 16
Simple ctrls: 8
Card29.Amixer.info:
Card hw: 29 'thinkpadec '/'thinkpad Console Audio Control at EC reg 0x30, fw 7XHT24WW-1.06'
Mixer name: 'thinkpad EC 7XHT24WW-1.06'
Components :''
Controls: 1
Simple ctrls: 1
Card29.Amixer. values:
Simple mixer control 'console', 0
Capabilities: pswitch-joined penum
Playback channels: Mono
Mono: Playback [on]
Date: Wed Apr 13 15:03:35 2011
EcryptfsInUse: Yes
HibernationDevice: RESUME = UUID = bb479652-f524-4abe-b1b0-27646d6deebc
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat"-Release Candidate amd64 (20100928)
MachineType: LENOVO 7465CTO
ProcEnviron:
LANGUAGE = en_US: en_GB: en
PATH = (custom, user)
LANG = en_US.UTF-8
SHELL =/bin/bash
Prockernel1_line: BOOT_IMAGE =/boot/vmlinuz-2.6.38-8-generic root = UUID = 266abe9a-19c2-4cc3-9ef7-238b729b6044 ro quiet splash libata. force = noncq vt. handoff = 7
RelatedPackageVersions:
Linux-restricted-modules-2.6.38-8-generic N/
Linux-backports-modules-2.6.38-8-generic N/
Linux-firmware 1.50
RfKill:
0: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
SourcePackage: linux
UpgradeStatus: Upgraded to natty on (7 days ago)
Dmi. bios. date: 11/10/2009
Dmi. bios. vendor: LENOVO
Dmi. bios. version: 6DET61WW (3.11)
Dmi. board. name: 7465CTO
Dmi. board. vendor: LENOVO
Dmi. board. version: Not Available
Dmi. chassis. asset. tag: No Asset Information
Dmi. chassis. type: 10
Dmi. chassis. vendor: LENOVO
Dmi. chassis. version: Not Available
Dmi. modalias: dmi: bvnLENOVO: Pushed (3.11): bd11/10/2009: svnLENOVO: pn7465CTO: pushed: rvnLENOVO: rn7465CTO: rvrNotAvailable: cvnLENOVO: ct10: cvrNotAvailable:
Dmi. product. name: 7465CTO
Dmi. product. version: ThinkPad X200s
Dmi. sys. vendor: LENOVO