After upgrading a computer from Centos3 to Centos5 an application that does a lot of scrolling took a very high performance hit. top tells me that X is using a lot of CPU and that was not happening before. The machine has an ATI Rage XL with 8MB and X is using the ati driver as there is no proprietary ATI driver for this board on linux.

The xorg.conf:

Section "Device"  
     Identifier  "Videocard0"  
     Driver      "ati"  
EndSection

Section "Screen"  
     Identifier "Screen0"  
     Device     "Videocard0"  
     DefaultDepth     24  
     SubSection "Display"  
             Viewport   0 0  
             Depth     24  
             Modes    "1024x768" "800x600" "640x480"  
     EndSubSection  
EndSection  

Section "DRI"  
     Group   0  
     Mode    0666  
EndSection

A similar machine that still has Centos3 installed is able to start DRI on the X server while this one is not, this is the Xorg.0.log for the Centos5 machine:

drmOpenDevice: node name is /dev/dri/card0   
drmOpenDevice: open result is -1, (No such device or address)  
drmOpenDevice: open result is -1, (No such device or address)  
drmOpenDevice: Open failed  
drmOpenDevice: node name is /dev/dri/card0  
drmOpenDevice: open result is -1, (No such device or address)  
drmOpenDevice: open result is -1, (No such device or address)  
drmOpenDevice: Open failed  
[drm] failed to load kernel module "mach64"  
(II) ATI(0): [drm] drmOpen failed  
(EE) ATI(0): [dri] DRIScreenInit Failed  
(II) ATI(0): Largest offscreen areas (with overlaps):  
(II) ATI(0):    1024 x 1279 rectangle at 0,768  
(II) ATI(0):    768 x 1280 rectangle at 0,768  
(II) ATI(0): Using XFree86 Acceleration Architecture (XAA)  
   Screen to screen bit blits  
      Solid filled rectangles  
      8x8 mono pattern filled rectangles  
      Indirect CPU to Screen color expansion  
      Solid Lines  
      Offscreen Pixmaps  
      Setting up tile and stipple cache:  
              32 128x128 slots  
              10 256x256 slots  
(==) ATI(0): Backing store disabled  
(==) ATI(0): Silken mouse enabled  
(II) ATI(0): Direct rendering disabled  
(==) RandR enabled

I also tried using EXA instead of XAA and setting:

Option "AccelMethod" "XAA"  
Option "XAANoOffscreenPixmaps" "true"

uname -a

Linux sir5.erg.inpe.br 2.6.18-128.7.1.el5 #1 SMP Mon Aug 24 08:20:55 EDT 2009 i686 i686 i386 GNU/Linux

rpm -qa | grep xorg-x11-server

xorg-x11-server-utils-7.1-4.fc6  
xorg-x11-server-sdk-1.1.1-48.52.el5  
xorg-x11-server-Xvfb-1.1.1-48.52.el5  
xorg-x11-server-Xnest-1.1.1-48.52.el5  
xorg-x11-server-Xorg-1.1.1-48.52.el5

The drmOpenDevice error continues when using the suggested Option "AIGLX" "true".