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[Bug 1351950] Re: Ubuntu does not put CPU into idle state

 

** Package changed: network-manager (Ubuntu) => powermanagement-
interface (Ubuntu)

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https://bugs.launchpad.net/bugs/1351950

Title:
  Ubuntu does not put CPU into idle state

Status in “powermanagement-interface” package in Ubuntu:
  New

Bug description:
  When booting into Windows partition, it manages to downclock and lower
  the V-core of my Intel i5-4570 CPU. This gives me a steady 25 C
  temperature during idle time. (measured with physical device and
  measured with Windows application called SpeedFan).

  On Ubuntu, this does not seem to happen. Even if I do echo "ondemand" | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor  , the CPU temperature is still about 40 C high during idle time. 
  I do this measurement after clean boot, CPU usage is 0-6% and temp is 40 C steady. 
  I use xsensors to look at my CPU temps and frequencies.

  This means that Ubuntu does not effectively downclock and lower the
  V-core of CPU when computer is in a idle state. I belive this is true
  to any version of Ubuntu now as I can see the effect on my Laptops
  that are using Ubuntu also. The battery life is much shorter than it
  is with Windows running on them.

  I have made my tests with a desktop computer using:

  CPU: i5-4570
  GPU: GTX 760
  Mobo: Asus B85-Plus
  OS: Ubuntu 14.04 64 bit

  Also made tests on various Lenovo thinkpads and Ultrabooks. Results
  remain the same, Ubuntu makes the CPU a lot hotter because of the
  reasons I posted.

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References