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[Bug 1497520] Re: Slow performance after resuming from/on battery (CPUs do not scale above 800MHz)


I could not trigger it using the upstream kernel for now

But it's maybe noteworthy, that the governors of CPU 1-3 get changed from "powersave" to "performance", regardless of using the Ubuntu or upstream kernel (/sys/devices/system/cpu/cpu*/cpufreq/scaling_governor).
That might be related to /etc/init.d/ondemand somehow, from Ubuntu's sysvinit package.

I am going to tag it as fixed upstream, but that's only from two tests,
and I have not found a reliable way to trigger this before already.

** Tags added: kernel-fixed-upstream

** Tags added: kernel-fixed-upstream-4.3-rc1

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

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  Slow performance after resuming from/on battery (CPUs do not scale
  above 800MHz)

Status in linux package in Ubuntu:

Bug description:
  I have noticed slow performance after resuming from STR on battery.

  I can not trigger this always, but it seems to be related to
  suspending and resuming while on battery.

  The CPU scaling governors look like this then:

  % cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

  % cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver 

  % cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq

  When watching the current CPU frequencies, it can be seen that they
  don't go above 800000 ('watch grep \"cpu MHz\" /proc/cpuinfo').

  I cannot see why they are limited to 800000.

  It looks like https://bugzilla.kernel.org/show_bug.cgi?id=61241, but
  /sys/devices/system/cpu/intel_pstate/max_perf_pct is at 100.

  Just writing the same setting for cpu0 again fixes it, and all CPUs
  will be scaled above 800MHz again:

  % echo powersave | sudo tee

  ProblemType: Bug
  DistroRelease: Ubuntu 15.04
  Package: linux-image-3.19.0-28-generic 3.19.0-28.30
  ProcVersionSignature: Ubuntu 3.19.0-28.30-generic 3.19.8-ckt5
  Uname: Linux 3.19.0-28-generic x86_64
  ApportVersion: 2.17.2-0ubuntu1.4
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Sat Sep 19 10:39:02 2015
  HibernationDevice: RESUME=UUID=d39463f5-889e-42ba-a729-f3f442f0c8dd
  InstallationDate: Installed on 2012-05-28 (1208 days ago)
  InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
  MachineType: LENOVO 42992PG
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-28-generic root=/dev/mapper/vg0-rootlv ro quiet splash
   linux-restricted-modules-3.19.0-28-generic N/A
   linux-backports-modules-3.19.0-28-generic  N/A
   linux-firmware                             1.143.3
  SourcePackage: linux
  UpgradeStatus: Upgraded to vivid on 2015-05-14 (127 days ago)
  dmi.bios.date: 05/14/2015
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 8DET70WW (1.40 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 42992PG
  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:bvr8DET70WW(1.40):bd05/14/2015:svnLENOVO:pn42992PG:pvrThinkPadX220Tablet:rvnLENOVO:rn42992PG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 42992PG
  dmi.product.version: ThinkPad X220 Tablet
  dmi.sys.vendor: LENOVO

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