Does CUDA support recursion?

Question

Does CUDA support recursion?

Answer 1

Sure it does, but it requires the Kepler architecture to do so. Check out their latest example on the classic quick sort.

http://blogs.nvidia.com/2012/09/how-tesla-k20-speeds-up-quicksort-a-familiar-comp-sci-code/

As far as i know, only latest Kepler GK110 supports dynamic parallelism, which allow this kind of recursive call and spawning of new threads within the kernel. Before Kepler GK110, it was not possible. And note that not all Kepler architecture supports this, only GK110 does.

If you need recursion, you probably need the Tesla K20. I'm not sure if Fermi does supports it,never read of it. :\ But Kepler sure does. =)

Answer 2

It does on NVIDIA hardware supporting compute capability 2.0 and CUDA 3.1:

New language features added to CUDA C / C++ include:

Support for function pointers and recursion make it easier to port many existing algorithms to Fermi GPUs

http://developer.nvidia.com/object/cuda_3_1_downloads.html

Function pointers: http://developer.download.nvidia.com/compute/cuda/sdk/website/CUDA_Advanced_Topics.html#FunctionPointers

Recursion: I can't find a code sample on NVIDIA's website, but on the forum someone post this:

__device__ int fact(int f)
{
  if (f == 0)
    return 1;
  else
    return f * fact(f - 1);
}

Answer 3

Only after 2.0 compute capability on compatible devices

Answer 4

Any recursive algorithm can be implemented with a stack and a loop. It's way more of a pain, but if you really need recursion, this can work.

Answer 5

Yeah, it is supported on the actual version. But despite the fact it is possible to execute recursive functions, you must have in mind that the memory allocation from the execution stack cannot be predicted (the recursive function must be executed in order to know the true depth of the recursion), so your stack could result being not enough for your purposes and it could need a manual increment of the default stack size

Answer 6

CUDA 3.1 supports recursion