41 lines
958 B
C++
41 lines
958 B
C++
#include <stdio.h>
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__global__ void saxpy(int n, float a, float *x, float *y) {
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int i = blockIdx.x * blockDim.x + threadIdx.x;
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if (i < n)
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y[i] = a * x[i] + y[i];
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}
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int main(void) {
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int N = 1 << 20;
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float *x, *y, *d_x, *d_y;
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x = (float *)malloc(N * sizeof(float));
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y = (float *)malloc(N * sizeof(float));
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cudaMalloc(&d_x, N * sizeof(float));
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cudaMalloc(&d_y, N * sizeof(float));
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for (int i = 0; i < N; i++) {
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x[i] = 1.0f;
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y[i] = 2.0f;
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}
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cudaMemcpy(d_x, x, N * sizeof(float), cudaMemcpyHostToDevice);
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cudaMemcpy(d_y, y, N * sizeof(float), cudaMemcpyHostToDevice);
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// Perform SAXPY on 1M elements
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// saxpy<<<(N+255)/256, 256>>>(N, 2.0f, d_x, d_y);
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cudaMemcpy(y, d_y, N * sizeof(float), cudaMemcpyDeviceToHost);
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float maxError = 0.0f;
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for (int i = 0; i < N; i++)
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maxError = max(maxError, abs(y[i] - 4.0f));
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printf("Max error: %f\n", maxError);
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cudaFree(d_x);
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cudaFree(d_y);
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free(x);
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free(y);
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}
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