Saul Luizaga schrieb:
>> Another possibility is to run the main renderer on the CPU, adding 
>> rays to queues, and sending any "sufficiently large" queues to the GPU 
>> for processing. I don't know if bandwidth limitations between the two 
>> would make this viable...
> 
> Exactly, that is why I asked: "Are absolutely sure there isn't a case 
> where a GPU can help? maybe in the middle of a rendering/parsing?".

Note that although the approach /may/ (!) work, it is a /fundamentally/ 
different approach from what POV-Ray is doing.

Changing POV-Ray to use that approach would imply virtually a complete 
rewrite of the render engine.

> As you can see, maybe bandwidth it isn't much of an issue since The 
> transfer between the PCIe video card and the Main memory can me made at 
> 5 GT/s. Is this still insufficient for POV-Ray peak performance?

So you're looking at peak data transfer rate limits and from them can 
infer that transfer between CPU and GPU memory space is not an issue?

Did you consider latency issues, or the overhead created by the OpenCL 
framework itself? How about the latency for a "function call"?

If your work packages are large enough, then these are no issues. But in 
a raytracer, be prepared for rather small work packages.

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