A question to brigdman or airlie XD about crossfire

[bridgman]

Typical GDDR5 data rates on shipping products are mid-way between PCIE 1 (2.5 Gbps per pin) and PCIE 2 (5.0 Gbps per pin), but in all cases you need an extremely wide bus to get the kind of bandwidth a modern GPU requires. An x16 or x32 bus isn't going to do the job.

The point I'm trying to make about OpenCL vs OpenGL is that if you structure the OpenCL app (or any compute app) properly you don't have to access data in the other GPU's memory very much in the first place.

[jrch2k8]

The OpenCL API takes a different approach -- it makes multiple processors directly visible to the app, so the application can decide how to split work between them. This generally means partitioning the data between processors and having each processor do "all the work" for the data it receives, which avoids the need to push data between processors, rather than running all of the data through all of the processors. Does that make any sense ?

yes it make sense but now is not all the efficient it should be cuz well even if that fix the hardware ooops with the link between GPUs the developer have to be extremely careful controling the code to avoid intergpu processing with really massive loops operations or it will suffer an slowdown or crash (and that explains why cuda apps mostly arent multigpu aware or are only for really expensive software). i think a more CPU aproach should be more efficient here for both opengl and opencl aka each gpu been electronicaly aware of the other and the ability to map memory for common use

[jrch2k8]

Typical GDDR5 data rates on shipping products are mid-way between PCIE 1 (2.5 Gbps per pin) and PCIE 2 (5.0 Gbps per pin), but in all cases you need an extremely wide bus to get the kind of bandwidth a modern GPU requires. An x16 or x32 bus isn't going to do the job.

The point I'm trying to make about OpenCL vs OpenGL is that if you structure the OpenCL app (or any compute app) properly you don't have to access data in the other GPU's memory very much in the first place.

well i agree too but it will help for really big operations XD and would be easier for developers XD lets wait for pcie 5.0 XD or fiber optics electronic or other cheaper superconductor