Xorg.conf tuning...

rarob at comcast.net rarob at comcast.net
Tue Apr 8 17:05:31 PDT 2008


Hello all,
  Could I get a guru or two to take a look at my xorg.conf and suggest improvements?  I've upgraded my
system and have hit a *noticeable* slowdown in performance, both real clock time as well as subjective
responsiveness.  
  The hardware is the same, so any differences are limited to the operating system and other software.  The
hardware is a dual 2.0 Ghz G5 PowerMac with an ATI Radeon 9600 (reported as RV350, has both a DVI
and an ADC connector on it).  Monitors are two Sceptre X20WG Nagas.  The previous OS was 
YellowDogLinux 4.0.91 (roughly Fedora Core4), and the new one is YellowDogLinux 6.0 (roughly 
RHEL5/CentOS5).  I've got my the xorg.conf from the YDL6 setup appended at the end.
  The behavior that I'm seeing is literally watching windows 'scroll' onto the screen (say 1/10 sec to map), 
and *very* slow updates to these windows from my application.  When I compare executions of the same
binaries running on  the YDL4.0.91 I see the windows 'pop' into existence and update quickly.  I believe there
may be an issue with the underlying Linux as well, as I see some performance slowdown even with graphics
turned off.  But top is showing X consuming a full cpu when my app is running under YDL6, vice at most 50% under  
YDL4.0.91.
  I'm tackling this issue from multiple fronts, and one of the linux kernel developers I've talked with suggested 
talking with this list.


====YDL6.0 /etc/X11/xorg.conf
# Xorg configuration created by system-config-display

Section "ServerLayout"
	Identifier     "Multihead layout"
	Screen      0  "Screen0" LeftOf "Screen1"
	Screen      1  "Screen1" 0 0
	InputDevice    "Mouse0" "CorePointer"
	InputDevice    "Keyboard0" "CoreKeyboard"
	Option	    "Xinerama" "off"
	Option	    "Clone" "on"
EndSection

Section "Files"
	RgbPath      "/usr/share/X11/rgb"
	ModulePath   "/usr/lib/xorg/modules"
	FontPath     "unix/:7100"
	FontPath     "built-ins"
EndSection

Section "Module"
	Load  "dri"
	Load  "vnc"
	Load  "record"
	Load  "dbe"
	Load  "xtrap"
	Load  "extmod"
	Load  "glx"
EndSection

Section "InputDevice"
	Identifier  "Keyboard0"
	Driver      "kbd"
EndSection

Section "InputDevice"
	Identifier  "Mouse0"
	Driver      "mouse"
	Option	    "Protocol" "auto"
	Option	    "Device" "/dev/input/mice"
	Option	    "ZAxisMapping" "4 5 6 7"
EndSection

Section "Monitor"
	Identifier   "Monitor0"
	VendorName   "Monitor Vendor"
	ModelName    "Monitor Model"
EndSection

Section "Monitor"
	Identifier   "Monitor1"
	VendorName   "Monitor Vendor"
	ModelName    "LCD Panel 1680x1050"
 ### Comment all HorizSync and VertSync values to use DDC:
#	HorizSync    31.5 - 67.0
#	VertRefresh  50.0 - 75.0
	Option	    "dpms"
EndSection

Section "Device"

        ### Available Driver options are:-
        ### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
        ### <string>: "String", <freq>: "<f> Hz/kHz/MHz"
        ### [arg]: arg optional
        #Option     "NoAccel"            	# [<bool>]
        #Option     "SWcursor"           	# [<bool>]
        #Option     "Dac6Bit"            	# [<bool>]
        #Option     "Dac8Bit"            	# [<bool>]
        #Option     "BusType"            	# [<str>]
        #Option     "CPPIOMode"          	# [<bool>]
        #Option     "CPusecTimeout"      	# <i>
        #Option     "AGPMode"            	# <i>
        #Option     "AGPFastWrite"       	# [<bool>]
        #Option     "AGPSize"            	# <i>
        #Option     "GARTSize"           	# <i>
        #Option     "RingSize"           	# <i>
        #Option     "BufferSize"         	# <i>
        #Option     "EnableDepthMoves"   	# [<bool>]
        #Option     "EnablePageFlip"     	# [<bool>]
        #Option     "NoBackBuffer"       	# [<bool>]
        #Option     "DMAForXv"           	# [<bool>]
        #Option     "FBTexPercent"       	# <i>
        #Option     "DepthBits"          	# <i>
        #Option     "AccelDFS"           	# [<bool>]
        #Option     "PanelOff"           	# [<bool>]
        #Option     "DDCMode"            	# [<bool>]
        #Option     "MonitorLayout"      	# [<str>]
        #Option     "IgnoreEDID"         	# [<bool>]
        #Option     "UseFBDev"           	# [<bool>]
        #Option     "MergedFB"           	# [<bool>]
        #Option     "CRT2HSync"          	# [<str>]
        #Option     "CRT2VRefresh"       	# [<str>]
        #Option     "CRT2Position"       	# [<str>]
        #Option     "MetaModes"          	# [<str>]
        #Option     "MergedDPI"          	# [<str>]
        #Option     "MergedXinerama"     	# [<bool>]
        #Option     "MergedXineramaCRT2IsScreen0" 	# [<bool>]
        #Option     "MergedNonRectangular" 	# [<bool>]
        #Option     "MergedMouseRestriction" 	# [<bool>]
        #Option     "DisplayPriority"    	# [<str>]
        #Option     "PanelSize"          	# [<str>]
        #Option     "ForceMinDotClock"   	# <freq>
        #Option     "ColorTiling"        	# [<bool>]
        #Option     "VideoKey"           	# <i>
        #Option     "RageTheatreCrystal" 	# <i>
        #Option     "RageTheatreTunerPort" 	# <i>
        #Option     "RageTheatreCompositePort" 	# <i>
        #Option     "RageTheatreSVideoPort" 	# <i>
        #Option     "TunerType"          	# <i>
        #Option     "RageTheatreMicrocPath" 	# <str>
        #Option     "RageTheatreMicrocType" 	# <str>
        #Option     "RenderAccel"        	# [<bool>]
        #Option     "SubPixelOrder"      	# [<str>]
        #Option     "ShowCache"          	# [<bool>]
        #Option     "DynamicClocks"      	# [<bool>]
        #Option     "BIOSHotkeys"        	# [<bool>]
        #Option     "VGAAccess"          	# [<bool>]
        #Option     "ReverseDDC"         	# [<bool>]
        #Option     "LVDSProbePLL"       	# [<bool>]
        #Option     "AccelMethod"        	# <str>
        #Option     "ConstantDPI"        	# [<bool>]
	Identifier  "Card0"
	Driver      "ati"
	VendorName  "ATI Technologies Inc"
	BoardName   "RV350 AP [Radeon 9600]"
	BusID       "PCI:240:16:0"
EndSection

Section "Device"
	Identifier  "Videocard1"
	Driver      "radeon"
	VendorName  "Videocard Vendor"
	BoardName   "ATI Technologies Inc RV350 AP [Radeon 9600]"
	BusID       "PCI:240:16:0"
	Screen      1
EndSection

Section "Screen"
	Identifier "Screen0"
	Device     "Card0"
	Monitor    "Monitor0"
	DefaultDepth     24
	SubSection "Display"
		Viewport   0 0
		Depth     24
		Modes    "1680x1050"
	EndSubSection
EndSection

Section "Screen"
	Identifier "Screen1"
	Device     "Videocard1"
	Monitor    "Monitor1"
	DefaultDepth     24
	SubSection "Display"
		Viewport   0 0
		Depth     24
		Modes    "1680x1050"
	EndSubSection
EndSection




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