In NIVIDIA CUDA Programming Guide 2.1:
The use of multiple GPUs as CUDA devices by an application running on a multi-GPU system is only guaranteed to work if these GPUs are of the same type. If the system is in SLI mode however, only one GPU can be used as a CUDA device since all the GPUs are fused at the lowest levels in the driver stack …
So …, if I have 2 GTX 285 (each has 240 processors, 1GB memory) work in SLI mode:
- Does CUDA recognize them as 1 device with 480 processors and 2GB memory or 1 device with 240 processors with 1GB memory?
- If CUDA recognizes them as 1 device with 480 processors and 2GB memory, are the threads automatically distributed to the 480 processors when a kernel is launched on the device? Is the 2GB memory shared by the GPUs or each GPU has the copy of the same data?