touch-packages team mailing list archive

[Daniel van Vugt <daniel.van.vugt@xxxxxxxxxxxxx>]

** Tags added: power-management

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https://bugs.launchpad.net/bugs/1479250

Title:
  unity8 process using CPU when the phone is idle

Status in QtMir:
  New
Status in The Ubuntu Power Consumption Project:
  New
Status in qtmir package in Ubuntu:
  New
Status in unity8 package in Ubuntu:
  New

Bug description:
  top reports the unity8 process is consuming about 1% CPU even when the
  phone is idle (screen on):

  11688 phablet   20   0  482184 101352  44872 S  1.0  5.4   0:37.10
  unity8

  This makes unity8 the top consumer of CPU. 1% on modern CPUs like you
  find in phones is actually a very large amount of work going on (~10
  million clock ticks spent executing instructions per second on a 1GHz
  core).

  $ system-image-cli -i
  current build number: 272
  device name: mako
  channel: ubuntu-touch/devel-proposed/ubuntu
  last update: 2015-07-29 05:53:01
  version version: 272
  version ubuntu: 20150729
  version device: 20150708
  version custom: 20150729

  Running eventstat shows this CPU time is being used in 5 events per
  second:

   Event/s PID   Task            Init Function             Callback
     36.36     0 [swapper/0]     hrtimer_start_range_ns    tick_sched_timer
      5.05 11688 unity8          hrtimer_start_range_ns    hrtimer_wakeup

  So it sounds like QtMir's frame dropper is the culprit.

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