E02_block_grid_size.cu

#include <cuda_runtime.h>
#include <stdio.h>

int main(int argc, char **argv) {
    int nElem = 1024;
    
    dim3 block (1024);
    dim3 grid ((nElem+block.x-1)/block.x);
    printf("grid.x %d block.x %d \n",grid.x, block.x);
    
    block.x = 512;
    grid.x = (nElem+block.x-1)/block.x;
    printf("grid.x %d block.x %d \n",grid.x, block.x);
    
    block.x = 256;
    grid.x = (nElem+block.x-1)/block.x;
    printf("grid.x %d block.x %d \n",grid.x, block.x);
    
    block.x = 128;
    grid.x = (nElem+block.x-1)/block.x;
    printf("grid.x %d block.x %d \n",grid.x, block.x);
    
    cudaDeviceReset();
    return(0);
}