CUDA Thread Indexing
1D grid of 1D blocks __device__ int getGlobalIdx_1D_1D() { return blockIdx.x *blockDim.x + threadIdx.x; } 1D grid of 2D blocks __device__ int getGlobalIdx_1D_2D() { return blockIdx.x * blockDim.x * blockDim.y + threadIdx.y * blockDim.x + threadIdx.x; } 1D grid of 3D blocks __device__ int getGlobalIdx_1D_3D() { return blockIdx.x * blockDim.x * blockDim.y * blockDim.z + threadIdx.z * blockDim.y * blockDim.x + threadIdx.y * blockDim.x + threadIdx.x; } { return blockIdx.x * blockDim.x * blockDim.y * blockDim.z + threadIdx.z * blockDim.y * blockDim.x + threadIdx.y * blockDim.x + threadIdx.x; } 2D grid of 1D blocks __device__ int getGlobalIdx_2D_1D() { int blockId = blockIdx.y * gridDim.x + blockIdx.x; int threadId = blockId * blockDim.x + threadIdx.x; return threadId; } { int blockId = blockIdx.y * gridDim.x + blockIdx.x; int threadId = blockId * blockDim.x + threadIdx.x; return threadId; } 2D grid of 2D blocks __device__ int getGlobalIdx_2D_2D() { int blockId = blockIdx.x + blockIdx.y * gridDim.x; int threadId = blockId * (blockDim.x * blockDim.y) + (threadIdx.y * blockDim.x) + threadIdx.x; return threadId; } 2D grid of 3D blocks __device__ int getGlobalIdx_2D_3D() { int blockId = blockIdx.x + blockIdx.y * gridDim.x; int threadId = blockId * (blockDim.x * blockDim.y * blockDim.z) + (threadIdx.z * (blockDim.x * blockDim.y)) + (threadIdx.y * blockDim.x) + threadIdx.x; return threadId; } 3D grid of 1D blocks __device__ int getGlobalIdx_3D_1D() { int blockId = blockIdx.x + blockIdx.y * gridDim.x + gridDim.x * gridDim.y * blockIdx.z; int threadId = blockId * blockDim.x + threadIdx.x; return threadId; } 3D grid of 2D blocks __device__ int getGlobalIdx_3D_2D() { int blockId = blockIdx.x + blockIdx.y * gridDim.x + gridDim.x * gridDim.y * blockIdx.z; int threadId = blockId * (blockDim.x * blockDim.y) + (threadIdx.y * blockDim.x) + threadIdx.x; return threadId; } 3D grid of 3D blocks __device__ int getGlobalIdx_3D_3D() { int blockId = blockIdx.x + blockIdx.y * gridDim.x + gridDim.x * gridDim.y * blockIdx.z; int threadId = blockId * (blockDim.x * blockDim.y * blockDim.z) + (threadIdx.z * (blockDim.x * blockDim.y)) + (threadIdx.y * blockDim.x) + threadIdx.x; return threadId; }