I would like to share some insights about multigpu in SDK 2.3 (WinXP32 & Linux64), and yes, I know that AMD officially doesn't support the second GPU on the HD5970, I hope they will give support before xmas 2011...
cal findnumdevices shows 2 devices; clinfo shows 2GPUs + 1 CPU (in inverse order, now there is GPU data first and then the CPU data)
My application has a parameter on which GPU work; 0 for the first one, 1 for the second and so on; I used to have 2xHD5970, I moved one to another machine. If I use GPU 0,everything goes fine, if I use GPU 1; the application crashes...
Again, cal findnumdevices shows 2 devices; clinfo shows 2GPUs + 1 CPU
if I open 2 terminals, two instances of the application using different GPUs can work and give correct results. But system performance drops down: moving a terminal window goes in slow motion (this didn't happen with SDK 2.2), the four processors in my system are working at 80% and ati-config shows 30%usage for the first GPU and 70% usage for the secong GPU (with minor variations).
I would like to know if someone see something similar or has different experiences. Thanks a lot