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[Rocko <rockorequin@xxxxxxxxxxx>]

Out of interest, why are all your cores running over 3.5GHz when you've
only loaded CPU 7? When acpi-cpufreq/ondemand was working properly on my
system, it would have had seven cores running near the minimum (0.8 GHz)
and the loaded one running at turbo.

Has anything been patched in the ondemand governor for Ubuntu's 3.11
kernel? Since I can manually change the CPU frequencies, it might be
that acpi-cpufreq has no issues, but the ondemand governor isn't
detecting the increase in load on my system. And it looks like the
problem doesn't carry across to the 'vanilla' 3.12.

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https://bugs.launchpad.net/bugs/1233479

Title:
  ondemand cpufreq governor does not scale CPU freq on Sandybridge

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  I notice that turbostat shows all cpus stuck at the minimum 800MHz
  (see attached log) on my system, even after rebooting twice. I used
  "stress --cpu 8" to confirm that the frequencies remained at 800MHz
  even under load.

  It looks like the system is using the acpi-cpufreq driver with the
  ondemand governor (has the default been changed so it does not use
  intel p-state, as per
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647?).

  
  Edit: See comment #1 below - it looks like I can manually change the cpu freq, but the governor cannot. Also, switching to use intel pstate fixes the problem.

  
  The only unusual thing I had done prior to this was to boot into the weekly build of 3.12-rc3 just prior (this kernel kept the frequencies rather high, typically over 2GHz, ie using a lot more power than usual, so I rebooted back into the standard kernel).

  This is the contents of the files in
  /sys/devices/system/cpu/cpu0/cpufreq/:

  affected_cpus:
  0
  bios_limit:
  2001000
  cpuinfo_cur_freq:
  800000
  cpuinfo_max_freq:
  2001000
  cpuinfo_min_freq:
  800000
  cpuinfo_transition_latency:
  10000
  freqdomain_cpus:
  0 1 2 3 4 5 6 7
  related_cpus:
  0
  scaling_available_frequencies:
  2001000 2000000 1900000 1800000 1700000 1600000 1500000 1400000 1300000 1200000 1100000 1000000 900000 800000
  scaling_available_governors:
  conservative ondemand userspace powersave performance
  scaling_cur_freq:
  800000
  scaling_driver:
  acpi-cpufreq
  scaling_governor:
  ondemand
  scaling_max_freq:
  2001000
  scaling_min_freq:
  800000
  scaling_setspeed:
  <unsupported>
  stats:

  ProblemType: Bug
  DistroRelease: Ubuntu 13.10
  Package: linux-image-3.11.0-9-generic 3.11.0-9.16
  ProcVersionSignature: Ubuntu 3.11.0-9.16-generic 3.11.2
  Uname: Linux 3.11.0-9-generic x86_64
  ApportVersion: 2.12.5-0ubuntu1
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  rocko      2813 F.... pulseaudio
  Date: Tue Oct  1 10:13:24 2013
  InstallationDate: Installed on 2012-08-25 (401 days ago)
  InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120724.2)
  MachineType: Dell Inc. Dell System XPS L502X
  MarkForUpload: True
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-9-generic root=UUID=67083065-b92e-4596-a218-817c1dfc8ae7 ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.11.0-9-generic N/A
   linux-backports-modules-3.11.0-9-generic  N/A
   linux-firmware                            1.115
  SourcePackage: linux
  UpgradeStatus: Upgraded to saucy on 2013-09-01 (30 days ago)
  dmi.bios.date: 05/29/2012
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A11
  dmi.board.name: 0NJT03
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A00
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.chassis.version: 0.1
  dmi.modalias: dmi:bvnDellInc.:bvrA11:bd05/29/2012:svnDellInc.:pnDellSystemXPSL502X:pvr:rvnDellInc.:rn0NJT03:rvrA00:cvnDellInc.:ct8:cvr0.1:
  dmi.product.name: Dell System XPS L502X
  dmi.sys.vendor: Dell Inc.

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