As Qt switched from v8 to v4 (replacing the code that triggered this)
and we haven't seen this in a long time, we can close this now.

** Changed in: unity8 (Ubuntu)
       Status: Confirmed => Incomplete

** Changed in: unity8 (Ubuntu)
       Status: Incomplete => Invalid

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https://bugs.launchpad.net/bugs/1219871

Title:
  when idle with screen blank, unity8 generates hundreds of context
  switches per second

Status in “unity8” package in Ubuntu:
  Invalid

Bug description:
  To reproduce (on maguro, Samsung Galaxy Nexus):

  sudo apt-get install sysstat

  ensure idle has occurred and screen is now blank, ssh in and run

  pidstat -w 10 1

  Linux 3.0.0-3-maguro (ubuntu-phablet)   09/02/2013      _armv7l_
  (2 CPU)

  03:04:13 PM   UID       PID   cswch/s nvcswch/s  Command
  03:04:23 PM     0         3      1.19      0.00  ksoftirqd/0
  03:04:23 PM     0         9      1.29      0.00  ksoftirqd/1
  03:04:23 PM     0        13      0.20      0.00  sync_supers
  03:04:23 PM     0        20     21.99      0.00  kworker/0:1
  03:04:23 PM     0        23      0.40      0.00  kinteractiveup
  03:04:23 PM     0        69      1.29      0.00  kworker/1:1
  03:04:23 PM     0        88      2.09      0.00  mmcqd/0
  03:04:23 PM     0        96      0.30      0.00  dhd_watchdog
  03:04:23 PM     0        97      8.46      0.00  dhd_dpc
  03:04:23 PM     0       156      0.90      0.00  jbd2/mmcblk0p12
  03:04:23 PM   103       418      0.50      0.00  dbus-daemon
  03:04:23 PM     0       429      0.20      0.00  flush-179:0
  03:04:23 PM  1000       493     70.05      0.00  surfaceflinger
  03:04:23 PM 32011       613      0.20      0.00  init
  03:04:23 PM 32011       658      0.10      0.00  dbus-daemon
  03:04:23 PM 32011       713    467.86      0.10  unity8
  03:04:23 PM 32011       788      0.10      0.00  upstart-dbus-br
  03:04:23 PM 32011       790      0.10      0.00  upstart-dbus-br
  03:04:23 PM     0       862      3.98      2.79  NetworkManager
  03:04:23 PM     0      1179      0.10      0.00  wpa_supplicant
  03:04:23 PM 32011      1219      0.10      0.40  indicator-netwo
  03:04:23 PM     0      1237      0.20      0.00  ofonod
  03:04:23 PM 32011      1335      0.10      0.00  mission-control
  03:04:23 PM 32011      1339      0.40      0.00  telepathy-ofono
  03:04:23 PM     0      1929    222.59      1.09  kworker/u:0
  03:04:23 PM     0      2379    222.89      0.00  kworker/u:1
  03:04:23 PM 32011      2944      0.10      2.19  pidstat

  unity8 with PID 713 is performing ~450-470 context switches a second.
  But what is it doing?

  sudo add-apt-repository ppa:colin-king/white && sudo apt-get update && sudo 
apt-get install health-check
  sudo health-check -p 713 -d 10

  CPU usage:
    PID  Process                USR%   SYS%  TOTAL%
     713 unity8                27.29   6.40  33.69 (medium load)

  ^^ that's kinda busy!

  Wakeups:
   No wakeups detected

  File I/O operations:
   No file I/O operations detected

  System calls traced:
    PID  Process              Syscall               Count    Rate/Sec
     713 unity8               futex                  3904     390.2976
     713 unity8               clock_gettime          1384     138.3637
     713 unity8               poll                    791      79.0792
     713 unity8               read                    789      78.8793
     713 unity8               recvmsg                   4       0.3999
     713 unity8               write                     4       0.3999
     713 unity8               restart_syscall           1       0.1000
   Total                                             6877     687.5196

  Looks like it may be context switching like mad on a futex.

  
  When the screen is not blank but device is idle, unity8 is far less busy.

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