Comment 34 for bug 760131

It might be a cludge, but a workaround might be to disable the
tickless kernel option, multiple core systems and hyperthreading
would still work with a slight increase in overhead- at least until
this has an accepted patch from the kernel folks.

On 5/12/11, nanog <email address hidden> wrote:
> Looks like the discussion at lkml has been going on for a long time.
>
> http://lkml.org/lkml/2010/4/26/249
>
> This history of this set of patches correlates well with the timeline of
> increased power consumption from phoronix testing. IMO, the loss of
> power consumption does not equal the benefit of increased kernel
> responsiveness especially for laptops.
>
>>I haven't tested this, but single CPU/single core machines might not be
>> affected by this,
> As one would expect this bug is present on hyperthreaded single core atom
> chips.
> For those who want increased battery life on their atom chips...2.6.34 is
> running terrifically in natty.
>
> --
> You received this bug notification because you are a direct subscriber
> of the bug.
> https://bugs.launchpad.net/bugs/760131
>
> Title:
> Power consumption raised significantly in natty
>
> Status in Release Notes for Ubuntu:
> Fix Released
> Status in “linux” package in Ubuntu:
> Confirmed
> Status in “linux” source package in Natty:
> Confirmed
> Status in “linux” source package in Oneiric:
> Confirmed
>
> 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 previously (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,00100000'
>    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 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
> ProcKernelCmdLine: 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/A
>  linux-backports-modules-2.6.38-8-generic N/A
>  linux-firmware 1.50
> RfKill:
>  0: phy0: Wireless LAN
>   Soft blocked: no
>   Hard blocked: no
> SourcePackage: linux
> UpgradeStatus: Upgraded to natty on 2011-04-06 (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:bvr6DET61WW(3.11):bd11/10/2009:svnLENOVO:pn7465CTO:pvrThinkPadX200s:rvnLENOVO:rn7465CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
> dmi.product.name: 7465CTO
> dmi.product.version: ThinkPad X200s
> dmi.sys.vendor: LENOVO
>
> === Release Notes ===
>
> Due to a regression inherited from the upstream linux kernel, Natty 11.04
> can exhibit a 10-30% increase in power consumption. This is a known issue
> which is actively being investigated. A SRU will be released onced a viable
> solution is found. For more information, please see
>
> http://www.phoronix.com/scan.php?page=article&item=linux_mobile_uffda&num=1
>
> To unsubscribe from this bug, go to:
> https://bugs.launchpad.net/ubuntu-release-notes/+bug/760131/+subscribe
>

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