Very slow performance with horizontal quad display

[tokamoto]

I'm trying to set up Xgl/compiz on SUSE Linux Enterprise Desktop 10 with two GeForce 7950 GX2.

tokamoto@sled10:~> /sbin/lspci | grep VGA
04:00.0 VGA compatible controller: nVidia Corporation G71 [GeForce 7950 GX2] (rev a1)
10:00.0 VGA compatible controller: nVidia Corporation G71 [GeForce 7950 GX2] (rev a1)

It has two outputs on each card.

These are configured as following without TwinView.

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" RightOf "Screen0"
    Screen      2  "Screen2" RightOf "Screen1"
    Screen      3  "Screen3" RightOf "Screen2"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "ServerFlags"
    Option         "Xinerama" "1"
EndSection

This configuration is for horizontal quad screens with Xinerama.

xdpyinfo -ext XINERAMA output:

XINERAMA version 1.1 opcode: 128
  head #0: 1024x768 @ 0,0
  head #1: 1024x768 @ 1024,0
  head #2: 1024x768 @ 2048,0
  head #3: 1024x768 @ 3072,0

This configuration is very poor performance.

Following configurations work good.

XINERAMA version 1.1 opcode: 128
  head #0: 800x600 @ 0,0
  head #1: 800x600 @ 800,0
  head #2: 800x600 @ 1600,0
  head #3: 800x600 @ 2400,0

XINERAMA version 1.1 opcode: 128
  head #0: 1024x768 @ 0,768
  head #1: 1024x768 @ 1024,768
  head #2: 1024x768 @ 0,0
  head #3: 1024x768 @ 1024,0

XINERAMA version 1.1 opcode: 128
  head #0: 1024x768 @ 0,0
  head #1: 1024x768 @ 1024,0
  head #2: 1024x768 @ 2048,0

I checked following info.
http://us.download.nvidia.com/XFree8...hapter-14.html

Why does this happen?
Could anybody help me?

Thank you!

[netllama]

XGL is software rendering. I'd expect poor performance, especially on large desktops with Xinerama.

[tokamoto]

I have replaced GeForce 8600 GT with 256MB x 2 and it works good.
All of software and configurations are same.
I don't think this is Xgl problem.
Just FYI.

[terianx]

tokamoto, I have tried to get my (2) 7950gx2 to work with this config and I get and error saying"

EE) Uanble to find display for devices 3
(EE) The request for configuration of display devices is not supported in the hardware

I currently only using 2 displays. two of the displays are connected to one videocard.

Can you tell me how to edit your config yo work with my system.