For the attached CUDA code dot.cu for dot product, please answer the following questions:

what is the purpose of the method __syncthreads() ?

In the kernel method dot(), the second __syncthreads() is executed for every thread even though only some of the threads are executing the instructions. Some smart people suggest the following updates (moving the __syncthreads() into if statement) to optimize the code

int i = blockDim.x/2;

while (i != 0) {

if (cacheIndex < i) {

cache[cacheIndex] += cache[cacheIndex + i];

__syncthreads();

}

i /= 2;

}.

Do you think this change will work?