← Back to team overview

touch-packages team mailing list archive

[Bug 1219871] Re: when idle with screen blank, unity8 generates hundreds of context switches per second

 

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

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to unity8 in Ubuntu.
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.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/unity8/+bug/1219871/+subscriptions