CUDA: synchronizing threads

Question

Almost anywhere I read about programming with CUDA there is a mention of the importance that all of the threads in a warp do the same thing.
In my code I have a situation wh

Answer 1

The answer to your question is no. You don't need to do anything special. Anyway, you can fix this, instead of your code you can do something like this:

buffer[x1] += (d1 < 0.5);
buffer[x2] += (d2 < 0.5);

You should check if you can use shared memory and access global memory in a coalesced pattern. Also be sure that you DON'T want to write to the same index in more than 1 thread.