Compiz uses high CPU when a hidden window refreshes frequently

[Mathieu Sivade]

What happens:
I noticed that Compiz uses about 35% of my CPU when I have a terminal window which frequently refreshes (displaying logs), even though that window is entirely hidden by other windows. However when minimized, the CPU usage drops to 'idle' (~1%).

What should happen:
A window that is not visible should not make compiz use more CPU than a minimized window.

Steps to repeat:
1. Launch a gnome terminal, maximize that window, and execute the following (to output stuff yet not too quickly):
  while [ 1 ] ; do perl -e 'select(undef,undef,undef,.1)' ; echo "blop" ; done
2. Open another gnome terminal, maximize it, run top: Compiz CPU usage is high
3. Mimize the first gnome terminal window
4. top should now show that Compiz CPU usage is very low (idle)

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: compiz-core 1:0.9.6+bzr20110929-0ubuntu6.1
ProcVersionSignature: Ubuntu 3.0.0-17.30-generic 3.0.22
Uname: Linux 3.0.0-17-generic i686
.tmp.unity.support.test.0:

ApportVersion: 1.23-0ubuntu4
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,regex,place,imgjpeg,grid,compiztoolbox,gnomecompat,resize,animation,vpswitch,mousepoll,imgpng,workarounds,snap,move,session,unitymtgrabhandles,wall,fade,expo,ezoom,scale,unityshell]
CompositorRunning: compiz
Date: Fri Apr 20 11:18:35 2012
DistUpgraded: Fresh install
DistroCodename: oneiric
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 4.1.2, 3.0.0-12-generic, i686: installed
 virtualbox, 4.1.2, 3.0.0-14-generic, i686: installed
 virtualbox, 4.1.2, 3.0.0-15-generic, i686: installed
 virtualbox, 4.1.2, 3.0.0-16-generic, i686: installed
 virtualbox, 4.1.2, 3.0.0-17-generic, i686: installed
ExecutablePath: /usr/bin/compiz
GraphicsCard:
 Intel Corporation 4 Series Chipset Integrated Graphics Controller [8086:2e12] (rev 03) (prog-if 00 [VGA controller])
   Subsystem: Hewlett-Packard Company Device [103c:3035]
   Subsystem: Hewlett-Packard Company Device [103c:3035]
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
MachineType: Hewlett-Packard HP Compaq dc7900 Convertible Minitower
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-17-generic root=UUID=090db51b-ae1f-4b91-9930-ba468e1376c3 ro quiet splash vt.handoff=7
SourcePackage: compiz
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/12/2011
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 786G1 v01.26
dmi.board.asset.tag: CZC9318ZDG
dmi.board.name: 3032h
dmi.board.vendor: Hewlett-Packard
dmi.chassis.asset.tag: CZC9318ZDG
dmi.chassis.type: 6
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr786G1v01.26:bd07/12/2011:svnHewlett-Packard:pnHPCompaqdc7900ConvertibleMinitower:pvr:rvnHewlett-Packard:rn3032h:rvr:cvnHewlett-Packard:ct6:cvr:
dmi.product.name: HP Compaq dc7900 Convertible Minitower
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.6+bzr20110929-0ubuntu6.1
version.libdrm2: libdrm2 2.4.26-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3.2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3.2
version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1

[jhfhlkjlj (fdsuufijjejejejej-deactivatedaccount)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 803943, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.