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/* File: vec_add.cu
* Purpose: Implement vector addition on a gpu using cuda
*
* Compile: nvcc [-g] [-G] -o vec_add vec_add.cu
* Run: ./vec_add
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <math.h>
__global__ void Vec_add(unsigned int x[], unsigned int y[], unsigned int z[], int n) {
int thread_id = blockIdx.x * blockDim.x + threadIdx.x;
if (thread_id < n){
z[thread_id] = x[thread_id] + y[thread_id];
}
}
int main(int argc, char* argv[]) {
int n, m;
unsigned int *h_x, *h_y, *h_z;
unsigned int *d_x, *d_y, *d_z;
size_t size;
/* Define vector length */
n = 2621440;
m = 320;
size = m * n * sizeof(unsigned int);
// Allocate memory for the vectors on host memory.
h_x = (unsigned int*) malloc(size);
h_y = (unsigned int*) malloc(size);
h_z = (unsigned int*) malloc(size);
for (int i = 0; i < n * m; i++) {
h_x[i] = i+1;
h_y[i] = n-i;
}
printf("Input size = %d\n", n * m);
// Print original vectors.
/*printf("h_x = ");
for (int i = 0; i < m; i++){
printf("%u ", h_x[i]);
}
printf("\n\n");
printf("h_y = ");
for (int i = 0; i < m; i++){
printf("%u ", h_y[i]);
}
printf("\n\n");*/
// Event creation
cudaEvent_t start, stop;
cudaEventCreate(&start);
cudaEventCreate(&stop);
float time1 = 0;
/* Allocate vectors in device memory */
cudaMalloc(&d_x, size);
cudaMalloc(&d_y, size);
cudaMalloc(&d_z, size);
/* Copy vectors from host memory to device memory */
cudaMemcpy(d_x, h_x, size, cudaMemcpyHostToDevice);
cudaMemcpy(d_y, h_y, size, cudaMemcpyHostToDevice);
// Start timer
cudaEventRecord( start, 0 );
/* Kernel Call */
Vec_add<<<(n * m) / 256, 256>>>(d_x, d_y, d_z, n * m);
// End timer
cudaEventRecord( stop, 0 );
cudaEventSynchronize( stop );
cudaEventElapsedTime( &time1, start, stop );
cudaMemcpy(h_z, d_z, size, cudaMemcpyDeviceToHost);
/*printf("The sum is: \n");
for (int i = 0; i < m; i++){
printf("%u ", h_z[i]);
}
printf("\n");*/
printf("Execution time = %f ms\n", time1);
/* Free device memory */
cudaFree(d_x);
cudaFree(d_y);
cudaFree(d_z);
/* Free host memory */
free(h_x);
free(h_y);
free(h_z);
return 0;
} /* main */
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