Comment 10 for bug 849782

Forwarding this bug from Ubuntu reporter Jonathan Lange:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/849782

[Problem]
When system is under load, the graphics experience periodic glitches.

Perhaps under the load of oneiric's Unity3D the driver isn't able to keep up with the graphics loads, and isn't able to fill the pipe 100% of the time? How could that be proved/disproved (or are we way off base?)

[Original Description]
I have a Lenovo X200 laptop, and I run Unity 3D. Every so often, since oneiric, my screen jitters. That is, it seems to jump up and down like it has a nervous twitch. I can't reproduce it exactly, but it seems more likely to happen when my system is under load.

I've monitored .xsession-errors when the twitch happens, and nothing is dumped there. I've also checked /var/crash/, but none of the crashes there have times that match the twitch.

Chris Halse Rogers suggested trying, "echo 0 > /sys/module/drm_kms_helper/parameters/poll", but that doesn't seem to correct the problem.

In addition, unity_support_test crashed while filing this bug.

DistroRelease: Ubuntu 11.10
Package: xserver-xorg 1:7.6+7ubuntu7
ProcVersionSignature: Ubuntu 3.0.0-10.16-generic 3.0.4
Uname: Linux 3.0.0-10-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 1.22.1-0ubuntu2
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,mousepoll,resize,gnomecompat,place,wall,vpswitch,move,regex,snap,session,animation,expo,workarounds,ezoom,staticswitcher,fade,scale,unityshell]
CompositorRunning: compiz
Date: Wed Sep 14 09:31:23 2011
DistUpgraded: Log time: 2011-07-26 11:37:40.528783
DistroCodename: oneiric
DistroVariant: ubuntu
EcryptfsInUse: Yes
ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu
GlAlternative: lrwxrwxrwx 1 root root 24 2010-03-20 18:53 /etc/alternatives/gl_conf -> /usr/lib/mesa/ld.so.conf
GraphicsCard:
 Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:20e4]
   Subsystem: Lenovo Device [17aa:20e4]
MachineType: LENOVO 7454A12
ProcEnviron:
 PATH=(custom, user)
 LANG=en_AU.UTF-8ProcKernelCmdLine: root=UUID=66c83d9d-bb68-4f51-995c-63e9b4ee025f ro quiet splash
SourcePackage: xorg
UnitySupportTest: Error: command ['/usr/lib/nux/unity_support_test', '-p', '-f'] failed with exit code -11:
UpgradeStatus: Upgraded to oneiric on 2011-07-26 (49 days ago)
dmi.bios.date: 07/30/2008
dmi.bios.vendor: LENOVO
dmi.bios.version: 6DET28WW (1.05 )
dmi.board.name: 7454A12
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6DET28WW(1.05):bd07/30/2008:svnLENOVO:pn7454A12:pvrThinkPadX200:rvnLENOVO:rn7454A12:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 7454A12
dmi.product.version: ThinkPad X200
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.5.94+bzr2803-0ubuntu1
version.ia32-libs: ia32-libs 20090808ubuntu20
version.libdrm2: libdrm2 2.4.26-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 7.11.0+git20110128.2a18d195-0ubuntu0sarvatt
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.11.0+git20110128.2a18d195-0ubuntu0sarvatt
version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7
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
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A