i wont go into detail about what they are, its way too confusing.
but whats important about them is
1) they are dissabled by default .
2) dissableing them causes a noticable drop in 3d graphics performance.
The reason they do this, is because some chipsets (some versions of VIA for example) become very unstable and crash when FastWirites are enabled.
this is rare... but, but defaulting to off, willsave Nvidia alot of money on the customer support side of things.
But many of you Nvidia users out there have hardware which is Stable with FastWrites and SBA,,but you are not using it.
FIRSTLY... before you go on, make sure that you have a rescue disk, AND you know how to use it, just incase your system is one of the few unstable chipsets. if you are unlucky enough to have an unstable chipset, you will need to boot the rescue disk, and edit a config file to resore your system to default... but more on that later.
to find out if your system is capable of SBA and FastWrites
run the following 2 commands...
CODE
cat /proc/driver/nvidia/agp/host-bridge
cat /proc/driver/nvidia/agp/card
cat /proc/driver/nvidia/agp/card
both commands MUST report that SBA and fastWrites are "Supported"
example output
QUOTE
bash-2.05b$ cat /proc/driver/nvidia/agp/
card host-bridge status
bash-2.05b$ cat /proc/driver/nvidia/agp/card
Fast Writes: Supported
SBA: Supported
AGP Rates: 8x 4x
Registers: 0x1f000e1b:0x1f004312
bash-2.05b$ cat /proc/driver/nvidia/agp/host-bridge
Host Bridge: PCI device 10de:00e1 (nVidia Corporation)
Fast Writes: Supported
SBA: Supported
AGP Rates: 8x 4x
Registers: 0x1f00421b:0x00000312
card host-bridge status
bash-2.05b$ cat /proc/driver/nvidia/agp/card
Fast Writes: Supported
SBA: Supported
AGP Rates: 8x 4x
Registers: 0x1f000e1b:0x1f004312
bash-2.05b$ cat /proc/driver/nvidia/agp/host-bridge
Host Bridge: PCI device 10de:00e1 (nVidia Corporation)
Fast Writes: Supported
SBA: Supported
AGP Rates: 8x 4x
Registers: 0x1f00421b:0x00000312
if your Host Bridge reports "Not supported" then you may need to enables it in your system Bios,, or update your bios... Otherwise, your system isnt capable of this performance tweak.
Now.. lets have a look at the current status of SBA and Fast Writes..
run the code
CODE
bash-2.05b$ cat /proc/driver/nvidia/agp/status
here is some example output...
QUOTE
bash-2.05b$ cat /proc/driver/nvidia/agp/status
Status: Enabled
Driver: AGPGART
AGP Rate: 8x
Fast Writes: Enabled
SBA: Enabled
Status: Enabled
Driver: AGPGART
AGP Rate: 8x
Fast Writes: Enabled
SBA: Enabled
Your SBA might already be enabled... but your Fast Wirtes Will be Disabled.
(if they are enabled... then this tweak has already been carried, possably by your distro vendor)
So far.....
you have seen alot of code, lots of quotes and yet not actually done anything.
the tweak is surprisingly simple..
make a backup of the file "/etc/modules.d/nvidia"
CODE
mv /etc/modules.d/nvidia /etc/modules.d/nvidia.backup
touch /etc/modules.d/nvidia
touch /etc/modules.d/nvidia
now open up the file /etc/modules.d/nvidia and add these lines.
QUOTE
# Nvidia drivers support
alias char-major-195 nvidia
alias /dev/nvidiactl char-major-195
options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1
alias char-major-195 nvidia
alias /dev/nvidiactl char-major-195
options nvidia NVreg_EnableAGPSBA=1 NVreg_EnableAGPFW=1
now reboot.
if your computer starts hard crashing shortly after the graphical user interface starts up, then boot your rescue disk, delete the file /etc/modules.d/nvidia and replace with the backup.
after a sucessfull rebott, check to see if FastWirtes was correctly enabled. by having anouther look at the following output...
CODE
bash-2.05b$ cat /proc/driver/nvidia/agp/status
now run your fave game
on my AMD64 3400+ and GeForce FX 5700LE this cuased a coonsiderable increace in performance on Ut2004 and other 1s person shooters.
