I wonder how you get such clean results in the GI using path tracing. Do you also calculate the direct light at each hit point of the path? Otherwise most paths wouldn’t ever reach the small area light source and thus resulting in a dark pixel color. Or do you use some kind of importance sampling?
The other question I would like to know is how do you use the cuda threads? Are you using bucket-rendering or some kind of image partitioning? Or do you use other techniques to avoid the watchdog time-out? Do you sum up the sampling values in your kernel or outside using the cpu?

Thanks in advance.

Daniel

Yep it wouldn’t be the persistant threads themselves that would reduce pressure, I would need to do less work in each job too. Of course this increases bandwidth requirements, atomic serialisation costs, etc since I must now save/restore state for each job as the lists get executed, so I have no idea how much of a win this will be in practise.

Although switching to a persistent threads based system won’t probably help your registers pressure issues.
Registers are statically allocated when a kernel is kicked on a multiprocessor, so for all your jobs handled by persistent threads you will pay the cost of your max reg usage on all of them (and perhaps even more).

The kernel is tiny: maybe a couple of hundred lines of C. Took a few evenings to get this far, but I have plenty of CPU reference code to copy from.