Xorg constantly uses near-100% CPU after 9.04->Karmic upgrade

[Matthew Paul Thomas]

Ubuntu Karmic beta (all updates installed), MacBook rev3 (early 2008)

On a system that has been upgraded from Ubuntu 9.04 to Karmic beta, Xorg constantly uses near-100% CPU, even when no windows are open. This is typical top output:
  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
  955 root 20 0 174m 39m 18m R 96 2.0 379:03.74 Xorg
10282 mpt 20 0 138m 46m 10m S 17 2.3 0:10.76 chromium-browse
10262 mpt 20 0 118m 29m 14m S 2 1.5 0:10.38 chromium-browse
 2447 mpt 20 0 115m 33m 16m S 1 1.7 3:41.62 xchat
...

A clean installation of Ubuntu Karmic on the same machine does not have the same problem, but the problem should never happen regardless.

This is not bug 345224, because it did not happen with 9.04, and Xorg never freezes.
It probably isn't bug 379780, because it did not happen with 9.04.
It isn't bug 439138, because it happens after every login.
And it isn't bug 293637, because it happens regardless of theme.

ProblemType: Bug
Architecture: i386
Date: Fri Oct 9 14:57:08 2009
DistroRelease: Ubuntu 9.10
MachineType: Apple Inc. MacBook4,1
NonfreeKernelModules: wl
Package: xorg 1:7.4+3ubuntu5
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.31-12-generic root=UUID=11cc112e-2fe8-415f-91d5-fd68b0f8dc1f ro quiet splash
ProcEnviron:
 LANGUAGE=en_NZ.UTF-8
 PATH=(custom, user)
 LANG=en_NZ.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-12.41-generic
RelatedPackageVersions:
 xserver-xorg 1:7.4+3ubuntu5
 libgl1-mesa-glx 7.6.0-1ubuntu1
 libdrm2 2.4.13-1ubuntu1
 xserver-xorg-video-intel 2:2.8.1-1ubuntu3
 xserver-xorg-video-ati 1:6.12.99+git20090825.fc74e119-0ubuntu3
SourcePackage: xorg
Uname: Linux 2.6.31-12-generic i686
dmi.bios.date: 02/09/08
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB41.88Z.00C1.B00.0802091535
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Mac-F22788A9
dmi.board.vendor: Apple Inc.
dmi.board.version: PVT
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 2
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F22788A9
dmi.modalias: dmi:bvnAppleInc.:bvrMB41.88Z.00C1.B00.0802091535:bd02/09/08:svnAppleInc.:pnMacBook4,1:pvr1.0:rvnAppleInc.:rnMac-F22788A9:rvrPVT:cvnAppleInc.:ct2:cvrMac-F22788A9:
dmi.product.name: MacBook4,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
fglrx: Not loaded
system:
 distro: Ubuntu
 architecture: i686kernel: 2.6.31-12-generic

[lspci]
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller [8086:2a02] (rev 03)
     Subsystem: Apple Computer Inc. Device [106b:00a1]

[Etienne Savard (esavard)]

On my system it happens only when I run firefox. When I close firefox, Xorg is near 20% cpu utilization.

[Etienne Savard (esavard)]

Updating my system with the command: sudo apt-get dist-upgrade

Corrected the problem.

[Allan Caeg (allancaeg)]

They're also talking about it here http://ubuntuforums.org/showthread.php?t=1289073

[Bryce Harrington (bryce)]

Are you still seeing this problem? The fix to bug 439138 was pretty significant and may have addressed this one even though the symptoms are different.

Note that hardly ever are X 100% CPU bug reports actually bugs in X. X is a server process which responds to client requests, and *usually* it is an out of control client driving the server to full cpu usage. Often simply going through the running processes and killing them one by one will identify the culprit. Note that the wayward client process may not have very high cpu usage itself (it's blocking on X typically).

[Matthew Paul Thomas (mpt)]

I am no longer seeing this problem; it went away when bug 439138 was fixed. My best guess is that I was mistaken about the bug persisting after logout. Thanks for following up on it.