96 lines
2.2 KiB
Plaintext
96 lines
2.2 KiB
Plaintext
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// Get from: https://github.com/olcf/vector_addition_tutorials
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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const double epsilon = 1e-6;
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// CUDA kernel. Each thread takes care of one element of c
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__global__ void vecAdd(double *a, double *b, double *c, int n)
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{
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// Get our global thread ID
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int id = blockIdx.x*blockDim.x+threadIdx.x;
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// Make sure we do not go out of bounds
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if (id < n)
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c[id] = a[id] + b[id];
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}
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int main( int argc, char* argv[] )
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{
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//cudaSetDevice(0);
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// Size of vectors
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int n = 100000;
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// Host input vectors
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double *h_a;
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double *h_b;
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//Host output vector
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double *h_c;
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// Device input vectors
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double *d_a;
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double *d_b;
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//Device output vector
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double *d_c;
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// Size, in bytes, of each vector
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size_t bytes = n*sizeof(double);
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// Allocate memory for each vector on host
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h_a = (double*)malloc(bytes);
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h_b = (double*)malloc(bytes);
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h_c = (double*)malloc(bytes);
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// Allocate memory for each vector on GPU
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cudaMalloc(&d_a, bytes);
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cudaMalloc(&d_b, bytes);
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cudaMalloc(&d_c, bytes);
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int i;
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// Initialize vectors on host
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for( i = 0; i < n; i++ ) {
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h_a[i] = sin(i)*sin(i);
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h_b[i] = cos(i)*cos(i);
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}
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// Copy host vectors to device
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cudaMemcpy( d_a, h_a, bytes, cudaMemcpyHostToDevice);
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cudaMemcpy( d_b, h_b, bytes, cudaMemcpyHostToDevice);
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int blockSize, gridSize;
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// Number of threads in each thread block
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blockSize = 1024;
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// Number of thread blocks in grid
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gridSize = (int)ceil((float)n/blockSize);
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// Execute the kernel
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vecAdd<<<gridSize, blockSize>>>(d_a, d_b, d_c, n);
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// Copy array back to host
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cudaMemcpy( h_c, d_c, bytes, cudaMemcpyDeviceToHost );
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// Sum up vector c and print result divided by n, this should equal 1 within error
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double sum = 0;
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for(i=0; i<n; i++)
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sum += h_c[i];
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sum/=(double)n;
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if(abs(sum-1.0)<epsilon)
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printf("PASS\n");
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else
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printf("FAIL\n");
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// Release device memory
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cudaFree(d_a);
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cudaFree(d_b);
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cudaFree(d_c);
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// Release host memory
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free(h_a);
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free(h_b);
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free(h_c);
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return 0;
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}
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