Is it possible to pass an array of pointers to a cuda kernel?
i am looking for something like this:
__global__ void Kernel(int **arr)
{
int *temp = arr[blockDim.x];
temp[blockIdx.x] = blockIdx.x;
}
How can i allocate cuda memory for such structure?
Memory allocation for such array is not a problem, you'll do this by cudaMalloc(sizeof(void*)*SIZE). However, writing correct values into it is main problem. Only way to change values in device memory from host function is actually copying information from host memory to device memory (cudaMemcpy() or cudaMemcpyToSymbol()). Thus, to write device pointers into device memory, we must have pointer to device memory in host memory, which I don't think is possible. (pointer which is stored in host variables allocated by cudaMalloc() isn't actual pointer in device memory). So, the only way to write correct values in the array is from kernel, which makes array of pointers unconvenient. I suggest using indexes instead of pointers, it is much better. Basically if in your array of indexes you have written {4,3,0,1,2} it means that first element points to some array in index 4, second one - to the 3rd element and so on. If you want to point multiple arrays, you should make indexing by some rule, in which you will fill the array of indexes and in which you will access memory from kernel.
I'm doing some image processing work in CUDA currently, and I recommend that you just allocate a linear memory buffer and use an indexing scheme rather than dealing with arrays of pointers. It's way, way simpler in my experience. My 2c.
