ubuntu-x-swat team mailing list archive

[Daniel van Vugt <vanvugt@xxxxxxxxx>]

** Description changed:

  The problem here is that incorrect information from the NVIDIA driver is
  tricking some software like Compiz into using an incorrect refresh rate,
  which makes the whole desktop look choppy.
  
- The cause of this framerate problem is the DynamicTwinView feature of the NVIDIA graphics driver. It appears to be a documented "feature" of the driver, and has been for several years:
- http://us.download.nvidia.com/XFree86/Linux-x86/280.13/README/xconfigoptions.html
- (Search for: DynamicTwinView)
+ The cause of this framerate problem is the DynamicTwinView feature of
+ the NVIDIA graphics driver. It appears to be a documented "feature" of
+ the driver, and has been for several years:
+ 
+ --- Quote from the NVIDIA documentation ---
+ Option "DynamicTwinView" "boolean"
+ Enable or disable support for dynamically configuring TwinView on this X screen. When DynamicTwinView is enabled (the default), the refresh rate of a mode (reported through XF86VidMode or XRandR) does not correctly report the refresh rate, but instead is a unique number such that each MetaMode has a different value. This is to guarantee that MetaModes can be uniquely identified by XRandR.
+ When DynamicTwinView is disabled, the refresh rate reported through XRandR will be accurate, but NV-CONTROL clients such as nvidia-settings will not be able to dynamically manipulate the X screen's MetaModes. TwinView can still be configured from the X config file when DynamicTwinView is disabled.
+ Default: DynamicTwinView is enabled.
+ --- End quote ---
+ [http://us.download.nvidia.com/XFree86/Linux-x86/280.13/README/xconfigoptions.html]
  
  WORKAROUND:
  
  (in /etc/X11/xorg.conf)
  Section "Device"
    Option "DynamicTwinView" "False"
  EndSection
  
  ORIGINAL DESCRIPTION:
  
  Binary package hint: xorg
  
  My Samsung SyncMaster 931BF does actually support 75 hz screen refresh
  rate, but xorg lets me choose only between 50 Hz and 54 Hz. Modification
  of /etc/X11/xorg.conf does not help. xorg worked ok on edgy.
  
  Here's some info:
  
  $ uname -a
  Linux Xel-Naga 2.6.20-10-generic #2 SMP Mon Mar 12 00:02:49 UTC 2007 i686 GNU/Linux
  
  $ apt-cache show xorg | grep Version
  Version: 1:7.2-0ubuntu7
  
  The video card is Nvidia GeForce 7300GS.
  
  ProblemType: Bug
  Architecture: i386
  Date: Thu Mar 15 21:08:22 2007
  DistroRelease: Ubuntu 7.04
  Uname: Linux Xel-Naga 2.6.20-10-generic #2 SMP Mon Mar 12 00:02:49 UTC 2007 i686 GNU/Linux

-- 
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https://bugs.launchpad.net/bugs/92599

Title:
  Incorrect (low/stuttering) refresh rate with NVIDIA driver

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