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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

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** Changed in: linux (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1390902

Title:
  scaling_min_freq wrong on Intel Core i{5,7} CPUs

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  On Ubuntu:
  > lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description:    Ubuntu 14.04.1 LTS
  Release:        14.04
  Codename:       trusty

  > uname -a
  Linux desk 3.13.0-39-generic #66-Ubuntu SMP Tue Oct 28 13:30:27 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

  on all my Intel Core i5 or i7 systems (desktop and laptop) CPU scaling does not work out of the box:
  > cpufreq-info
  cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
  Report errors and bugs to cpufreq@xxxxxxxxxxxxxxx, please.
  analyzing CPU 0:
    driver: acpi-cpufreq
    CPUs which run at the same hardware frequency: 0
    CPUs which need to have their frequency coordinated by software: 0
    maximum transition latency: 10.0 us.
    hardware limits: 1.60 GHz - 3.50 GHz
    available frequency steps: 3.50 GHz, 3.50 GHz, 3.40 GHz, 3.20 GHz, 3.10 GHz, 3.00 GHz, 2.80 GHz, 2.70 GHz, 2.50 GHz, 2.40 GHz, 2.30 GHz, 2.10 GHz, 2.00 GHz, 1.90 GHz, 1.70 GHz, 1.60 GHz
    available cpufreq governors: conservative, ondemand, userspace, powersave, performance
    current policy: frequency should be within 3.50 GHz and 3.50 GHz.
                    The governor "ondemand" may decide which speed to use
                    within this range.
    current CPU frequency is 3.50 GHz.
    cpufreq stats: ...

  The problem is that although the hardware limits are correctly
  detected only the "range" between 3.50 and 3.50 GHz is used.

  A workaround that works on all of my systems is:
  > cat cpufreq_workaround.sh
  #!/bin/sh
  min_freq=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies | awk "{ print \$NF }")
  echo "Setting scaling_min_freq to $min_freq"
  for i in `seq 0 7`; do echo $min_freq > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_min_freq; done

  afterwards:
  > cpufreq-info
  cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
  Report errors and bugs to cpufreq@xxxxxxxxxxxxxxx, please.
  analyzing CPU 0:
    driver: acpi-cpufreq
    CPUs which run at the same hardware frequency: 0
    CPUs which need to have their frequency coordinated by software: 0
    maximum transition latency: 10.0 us.
    hardware limits: 1.60 GHz - 3.50 GHz
    available frequency steps: 3.50 GHz, 3.50 GHz, 3.40 GHz, 3.20 GHz, 3.10 GHz, 3.00 GHz, 2.80 GHz, 2.70 GHz, 2.50 GHz, 2.40 GHz, 2.30 GHz, 2.10 GHz, 2.00 GHz, 1.90 GHz, 1.70 GHz, 1.60 GHz
    available cpufreq governors: conservative, ondemand, userspace, powersave, performance
    current policy: frequency should be within 1.60 GHz and 3.50 GHz.
                    The governor "ondemand" may decide which speed to use
                    within this range.
    current CPU frequency is 1.60 GHz.
  ...

  This issue persisted over all dist-upgrades since installing Ubuntu
  14.04.1.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-3.13.0-39-generic 3.13.0-39.66
  ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
  Uname: Linux 3.13.0-39-generic x86_64
  NonfreeKernelModules: fglrx
  ApportVersion: 2.14.1-0ubuntu3.5
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC1:  ahb        3853 F.... pulseaudio
   /dev/snd/controlC0:  ahb        3853 F.... pulseaudio
  Date: Sun Nov  9 13:54:23 2014
  HibernationDevice: RESUME=UUID=1968620e-56f2-4ec6-b4ae-d2c601e8caa5
  InstallationDate: Installed on 2014-08-28 (72 days ago)
  InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
  IwConfig:
   eth0      no wireless extensions.
   
   eth1      no wireless extensions.
   
   lo        no wireless extensions.
  MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
  ProcFB:
   0 VESA VGA
   1 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-39-generic root=UUID=98ea3432-7344-4034-8652-46e5edf53f5b ro quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.13.0-39-generic N/A
   linux-backports-modules-3.13.0-39-generic  N/A
   linux-firmware                             1.127.8
  RfKill:
   
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 05/14/2012
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: P1.40
  dmi.board.name: Z77 Extreme4
  dmi.board.vendor: ASRock
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.40:bd05/14/2012:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnZ77Extreme4:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: To Be Filled By O.E.M.
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: To Be Filled By O.E.M.

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