Create vector_addition.cu

examples/cuda/vector_addition.cu

@@ -0,0 +1,85 @@
+// from https://github.com/olcf-tutorials/vector_addition_cuda/blob/master/vector_addition.cu
+
+#include <stdio.h>
+
+// Size of array
+#define N 1048576
+
+// Kernel
+__global__ void add_vectors(double *a, double *b, double *c)
+{
+	int id = blockDim.x * blockIdx.x + threadIdx.x;
+	if(id < N) c[id] = a[id] + b[id];
+}
+
+// Main program
+int main()
+{
+	// Number of bytes to allocate for N doubles
+	size_t bytes = N*sizeof(double);
+
+	// Allocate memory for arrays A, B, and C on host
+	double *A = (double*)malloc(bytes);
+	double *B = (double*)malloc(bytes);
+	double *C = (double*)malloc(bytes);
+
+	// Allocate memory for arrays d_A, d_B, and d_C on device
+	double *d_A, *d_B, *d_C;
+	cudaMalloc(&d_A, bytes);
+	cudaMalloc(&d_B, bytes);
+	cudaMalloc(&d_C, bytes);
+
+	// Fill host arrays A and B
+	for(int i=0; i<N; i++)
+	{
+		A[i] = 1.0;
+		B[i] = 2.0;
+	}
+
+	// Copy data from host arrays A and B to device arrays d_A and d_B
+	cudaMemcpy(d_A, A, bytes, cudaMemcpyHostToDevice);
+	cudaMemcpy(d_B, B, bytes, cudaMemcpyHostToDevice);
+
+	// Set execution configuration parameters
+	//		thr_per_blk: number of CUDA threads per grid block
+	//		blk_in_grid: number of blocks in grid
+	int thr_per_blk = 256;
+	int blk_in_grid = ceil( float(N) / thr_per_blk );
+
+	// Launch kernel
+	add_vectors<<< blk_in_grid, thr_per_blk >>>(d_A, d_B, d_C);
+
+	// Copy data from device array d_C to host array C
+	cudaMemcpy(C, d_C, bytes, cudaMemcpyDeviceToHost);
+
+	// Verify results
+    double tolerance = 1.0e-14;
+	for(int i=0; i<N; i++)
+	{
+		if( fabs(C[i] - 3.0) > tolerance)
+		{
+			printf("\nError: value of C[%d] = %d instead of 3.0\n\n", i, C[i]);
+			exit(1);
+		}
+	}
+
+	// Free CPU memory
+	free(A);
+	free(B);
+	free(C);
+
+	// Free GPU memory
+	cudaFree(d_A);
+	cudaFree(d_B);
+	cudaFree(d_C);
+
+	printf("\n---------------------------\n");
+	printf("__SUCCESS__\n");
+	printf("---------------------------\n");
+	printf("N                 = %d\n", N);
+	printf("Threads Per Block = %d\n", thr_per_blk);
+	printf("Blocks In Grid    = %d\n", blk_in_grid);
+	printf("---------------------------\n\n");
+
+	return 0;
+}