Geforce GTX SLI under Linux
I'm thinking of getting a pair of GTX 470's to SLI under Linux, so I was reading some information and found this in the readme of the latest Linux driver. As it says, it would be only temporary, but I coudln't help noticing it's in the readme a very long time already: driver 180+ and even older.
Why is Doom 3 slower when SLI or Multi-GPU is enabled?
The NVIDIA Accelerated Linux Graphics Driver does not automatically detect the optimal SLI or Multi-GPU settings for games such as Doom 3 and Quake 4. To work around this issue, the environment variable __GL_DOOM3 can be set to tell OpenGL that Doom 3's optimal settings should be used. In Bash, this can be done in the same command that launches Doom 3 so the environment variable does not remain set for other OpenGL applications started in the same session:
% __GL_DOOM3=1 doom3
Doom 3's startup script can also be modified to set this environment variable:
# Needed to make symlinks/shortcuts work.
# the binaries must run with correct working directory
exec ./doom.x86 "$@"
This environment variable is temporary and will be removed in the future.
So a couple of questions about this:
- Does it really still apply or did someone forget to remove it from the readme?
- To fix this for Quake 4 (and maybe Prey too?), do we have to use the same variable with the same name (__GL_DOOM3) or is it called different?
- When I enable SLI in xorg.conf, should I have 2 sections "device" for both cards?
Thanks for your help,
Last edited by Ulukai; 07-26-10 at 03:06 AM.