--- dri-howto.xml.orig 2005-12-23 08:43:01.000000000 -0800 +++ dri-howto.xml 2005-12-23 10:04:41.000000000 -0800 @@ -20,8 +20,8 @@ -1.0.15 -2005-12-16 +1.0.16 +2005-12-23 Introduction @@ -436,14 +436,64 @@

-A few options may increase performance by up to 30 percent (or more) over the -default. Set them in /etc/X11/xorg.conf. +A few options may increase performance by up to 30 percent (or more) over the +default. Set them in /etc/X11/xorg.conf. However, you will first +need to check that your motherboard and video card support these options.

+

+First, let's check the supported modes of your video cards, and see if your it +supports fast writes. Remember to replace nvidia with the actual name of +your device in /proc/driver/nvidia/. +

+ +
+$ cat /proc/driver/nvidia/agp/card
+
+Fast Writes:     Supported
+SBA:             Not Supported
+AGP Rates:       4x 2x 1x
+Registers:       0x1f000017:0x1f000104
+
+ +

+This shows that my card is capable of Fast Writes, which can noticeably improve +performance, as you will see later. However, the card does not support side +band addressing (SBA, a great way to make your hardware to deliver the +performance it should). However, it is capable of writing at 4x, which is the +ideal setting, and should be used by default. +

+ +

+Next, let's check out the capabilities of the motherboard: +

+ +
+$ cat /proc/driver/nvidia/agp/host-bridge
+
+Host Bridge:     Intel Corporation 82815 815 Chipset Host Bridge and Memory Controller Hub
+Fast Writes:     Not Supported
+SBA:             Supported
+AGP Rates:       4x 2x 1x
+Registers:       0x1f000207:0x00000104
+
+ +

+Unfortunately, though my motherboard supports SBA, it does not support Fast +Writes. This means that I can use neither Fast Writes nor side band addressing, +as both components need to support them. However, your hardware may support +both. If it does, you can try out the example settings below. +

+ + +Remember, the modes and capabilities for your video card and motherboard must +match for these settings to work! + + 
 Section "Device"
   Option     "AGPMode" "4"
-  (This increased FPS from 609 to 618.)
+  This increased FPS from 609 to 618. This sets the card to run at 4x speed. Use the multiples provided in your /proc info.
   Option     "AGPFastWrite" "True"
   (This had no measurable effect, but it may increase instability of your computer.)
   (You may also need to set it in your BIOS.)
@@ -453,6 +503,17 @@
 EndSection
+ +Note that enabling AGPFastWrite on a VIA chipset will very likely cause +your machine to lock up. VIA chipsets do not play nice with fast writes, so use +this setting at your own risk. + + + +Remember, if you want fast writes and sideband addressing to work properly, you +will have to first enable them in your BIOS. + +

If you want to set even more features, check out the feature matrix on