Create dotProd.cu

dotProd.cu

@@ -0,0 +1,98 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+__global__ void dotProd(float *d_a, float *d_b, float *d_c, float *prodVec, int N) {
+    int col = blockIdx.x * blockDim.x + threadIdx.x;
+
+	// element-wise products
+	if (tid < N) {
+		prodVec[tid] = d_a[tid] * d_b[tid];
+	}
+
+	// determine amount of padding for parallel reduction
+	int padding = 0;
+	for (int e = 0; (float)N/(float)(1 << e)>= 1; ++e) {
+	      	padding = e + 1;
+	}
+
+	for (int i = 0; i < (1 << padding) - N; ++i) {
+		prodVec[N + i] = 0;
+	}
+
+	__syncthreads();
+
+	// sum using parallel reduction
+	for (int stride = 1 << padding; stride >= 1; stride /= 2) {
+		if (tid < stride) {
+			prodVec[tid] += prodVec[tid + stride];
+		}
+	}	
+
+	__syncthreads();
+
+	d_c[0] = prodVec[0];
+}
+
+
+int main() {
+	// var declaration and memory allocation
+	int N = 5;
+	float *h_a, *h_b, *h_c;
+	float *d_a, *d_b, *d_c;
+	float *prodVec;
+
+    // memory allocation
+	h_a = (float *)malloc(N * sizeof(float));
+	h_b = (float *)malloc(N * sizeof(float));
+	h_c = (float *)malloc(1 * sizeof(float));
+
+	cudaMalloc((void**)&d_a, N * sizeof(float));
+	cudaMalloc((void**)&d_b, N * sizeof(float));
+	cudaMalloc((void**)&d_c, 1 * sizeof(float));
+	cudaMalloc((void**)&prodVec, 2 * N * sizeof(float));
+
+	// populate vectors with data	
+	for (int i = 0; i < N; ++i) {
+		h_a[i] = (float) (rand() % 10 + 1);
+		h_b[i] = (float) (rand() % 10 + 1);
+	}
+
+	cudaMemcpy(d_a, h_a, N * sizeof(float), cudaMemcpyHostToDevice);
+	cudaMemcpy(d_b, h_b, N * sizeof(float), cudaMemcpyHostToDevice);
+
+	// launch kernel instance
+	dotProd<<<1, N>>>(d_a, d_b, d_c, prodVec, N);
+
+	// copy results to CPU
+	cudaMemcpy(h_c, d_c, 1 * sizeof(float), cudaMemcpyDeviceToHost);
+
+    // print results
+	printf("A:\n--------\n");
+        for(int i = 0; i < N; ++i) {
+                printf("%f ", h_a[i]);
+                printf("\n");
+        }
+
+        printf("--------\n");
+        printf("B:\n--------\n");
+        for(int i = 0; i < N; ++i) {
+                printf("%f ", h_b[i]);
+                printf("\n");
+        }
+
+        printf("--------\n");
+        printf("C:\n");
+        printf("%f ", h_c[0]);
+        printf("\n--------\n");
+
+	// clean up memory
+	cudaFree(d_a);
+	cudaFree(d_b);
+	cudaFree(d_c);
+
+	free(h_a);
+	free(h_b);
+	free(h_c);
+
+	return 0;
+}