CUDA编程模型系列二(向量操作)

CUDA编程模型系列二(向量操作)

本系列教程将介绍具体的CUDA编程代码的细节

CUDA编程模型系列二(向量操作)

#include <stdio.h>
#include <math.h>


//x[] + y[] = z[]
__global__ void vecAdd(const double *x, const double *y, double *z, int count)
{
    
    
    const int index = blockDim.x * blockIdx.x + threadIdx.x;
    // t00 t01 t02 t10 t11 t12 t20 t21 t22
    if( index < count)
    {
    
    
        z[index] = x[index] + y[index];
    }
}

void vecAdd_cpu(const double *x, const double *y, double *z, int count)
{
    
    
    for(int i = 0; i<count; ++i)
    {
    
    
        z[i] = x[i] + y[i];
    }
}


int main()
{
    
    
    const int N = 1000;
    const int M = sizeof(double) * N;

    //cpu mem alloc
    double *h_x = (double*) malloc(M);
    double *h_y = (double*) malloc(M);
    double *h_z = (double*) malloc(M);
    double *result_cpu = (double*) malloc(M);

    for( int i = 0; i<N; ++i)
    {
    
    
        h_x[i] = 1;
        h_y[i] = 2;
    }

    double *d_x, *d_y, *d_z;
    cudaMalloc((void**) &d_x, M );
    cudaMalloc((void**) &d_y, M );
    cudaMalloc((void**) &d_z, M );

    cudaMemcpy(d_x ,h_x ,M , cudaMemcpyHostToDevice);
    cudaMemcpy(d_y ,h_y ,M , cudaMemcpyHostToDevice);

    const int block_size = 128;
    const int grid_size  = (N + block_size -1)/block_size;

    vecAdd<<<grid_size, block_size>>>(d_x, d_y, d_z, N);

    cudaMemcpy( h_z, d_z, M, cudaMemcpyDeviceToHost);

    vecAdd_cpu(h_x, h_y, result_cpu, N);

    bool error = false;

    for(int i=0; i<N; ++i)
    {
    
    
        if(fabs(result_cpu[i] - h_z[i]) > (1.0e-10))
        {
    
    
            error = true;
        }
    }
    printf("Result: %s\n", error?"Errors":"Pass");

    free(h_x);
    free(h_y);
    free(h_z);
    free(result_cpu);
    cudaFree(d_x);
    cudaFree(d_y);
    cudaFree(d_z);

}