I’m writing a CFD simulation program for GPUs. The program schedules the simulations, and can run paralelly 2 different simulations on the GTX295 I have. The problem is, that it’s not as fast as it should (at least I think).
CPU: Intel Extreme 975
Motherboard: Asus P6T SE
Memory: 12 GB DDR3 (now on 1066MHz).
GPU: GTX295 (Asus)
OS: Windows Vista x64 Business
NVIDIA Control Panel Settings: PhysX OFF, Multi-GPU Support: ON
If I run only one simulation with a specific settings, then it finishes in 21m:40s, if I run 2 of them, they finish in 33m:22s and 29m:20s, so the total performance is only 33% bigger. The program does not send more than 200 MB during the total run-time between the GPU and the CPU, so the PCI Express cannot cause the difference.
I also tested the n-body from the SDK. If run only on one GPU, it measures 304 GFlops, if run on 2 (I have forced to run on two different devices), then 303 and 120.
Is it normal? Does anybody know what causes it?
Thanks in advance! Yours sincerely: Laszlo Daroczy