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[Shevek <1535426@xxxxxxxxxxxxxxxxxx>]

Also related?
https://bugzilla.kernel.org/show_bug.cgi?id=90421
https://askubuntu.com/questions/582805/high-cpu-frequency-at-idle

Workaround from that bug: Force low power state:

shevek@raven:/sys/devices/system/cpu/intel_pstate$ cpupower frequency-info
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 500 MHz - 3.20 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 500 MHz and 2.80 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 3.19 GHz.
  boost state support:
    Supported: yes
    Active: yes
shevek@raven:/sys/devices/system/cpu/intel_pstate$ sudo cpupower frequency-set -g powersave
Setting cpu: 0
Setting cpu: 1
Setting cpu: 2
Setting cpu: 3
shevek@raven:/sys/devices/system/cpu/intel_pstate$ cpupower frequency-info
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 500 MHz - 3.20 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 500 MHz and 2.80 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.20 GHz.
  boost state support:
    Supported: yes
    Active: yes
shevek@raven:/sys/devices/system/cpu/intel_pstate$ grep MHz /proc/cpuinfo 
cpu MHz         : 1300.000
cpu MHz         : 1405.726
cpu MHz         : 1200.062
cpu MHz         : 1229.617

Now it's scaled down again.

** Bug watch added: Linux Kernel Bug Tracker #90421
   http://bugzilla.kernel.org/show_bug.cgi?id=90421

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Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1535426

Title:
  CPU runs at high speed after upgrade

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  After a dist-upgrade from 15.04 to 15.10, moving from kernel 3.19.0-43
  to 4.2.0-23, my laptop CPU runs continuously at 3GHz, and never slows
  down to 800MHz, as it used to. This has reduced my battery life from
  24 hours to 8 hours.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: linux-image-4.2.0-23-generic 4.2.0-23.28
  ProcVersionSignature: Ubuntu 4.2.0-23.28-generic 4.2.6
  Uname: Linux 4.2.0-23-generic x86_64
  ApportVersion: 2.19.1-0ubuntu5
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC1:  shevek     2664 F.... pulseaudio
   /dev/snd/controlC0:  shevek     2664 F.... pulseaudio
  CurrentDesktop: XFCE
  Date: Mon Jan 18 11:38:29 2016
  HibernationDevice: RESUME=UUID=22fd2208-7557-432d-bbff-95dd97905323
  InstallationDate: Installed on 2015-05-18 (244 days ago)
  InstallationMedia: Xubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422.1)
  MachineType: LENOVO 20CKCT01WW
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.2.0-23-generic.efi.signed root=/dev/mapper/xubuntu--vg-root ro noprompt persistent quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-4.2.0-23-generic N/A
   linux-backports-modules-4.2.0-23-generic  N/A
   linux-firmware                            1.149.3
  SourcePackage: linux
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: Upgraded to wily on 2016-01-17 (1 days ago)
  dmi.bios.date: 08/20/2015
  dmi.bios.vendor: LENOVO
  dmi.bios.version: N11ET34W (1.10 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 20CKCT01WW
  dmi.board.vendor: LENOVO
  dmi.board.version: 0B98417 WIN
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: None
  dmi.modalias: dmi:bvnLENOVO:bvrN11ET34W(1.10):bd08/20/2015:svnLENOVO:pn20CKCT01WW:pvrThinkPadT550:rvnLENOVO:rn20CKCT01WW:rvr0B98417WIN:cvnLENOVO:ct10:cvrNone:
  dmi.product.name: 20CKCT01WW
  dmi.product.version: ThinkPad T550
  dmi.sys.vendor: LENOVO

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