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#include <stdio.h> | |
#include <iostream> | |
#include <time.h> | |
// GPUで計算する際の関数 | |
__global__ void gpu_function(float *d_x, float *d_y) | |
{ | |
int i = blockIdx.x * blockDim.x + threadIdx.x; | |
d_y[i] = sin(d_x[i]) * sin(d_x[i]) + cos(d_x[i]) * cos(d_x[i]); | |
} | |
// CPUで計算する際の関数 | |
void cpu_function(int n, float *x, float *y) | |
{ | |
for (int i = 0; i < n; i++) { | |
y[i] = sin(x[i]) * sin(x[i]) + cos(x[i]) * cos(x[i]); | |
} | |
} | |
// main function | |
int main(void) | |
{ | |
bool GPU = true; | |
int N = 1000000; | |
float *host_x, *host_y, *dev_x, *dev_y; | |
// CPU側の領域確保 | |
host_x = (float*)malloc(N * sizeof(float)); | |
host_y = (float*)malloc(N * sizeof(float)); | |
// 乱数値を入力する | |
for (int i = 0; i < N; i++) { | |
host_x[i] = rand(); | |
} | |
int start = clock(); | |
if (GPU == true) { | |
// デバイス(GPU)側の領域確保 | |
cudaMalloc(&dev_x, N * sizeof(float)); | |
cudaMalloc(&dev_y, N * sizeof(float)); | |
// CPU⇒GPUのデータコピー | |
cudaMemcpy(dev_x, host_x, N * sizeof(float), cudaMemcpyHostToDevice); | |
// GPUで計算 | |
gpu_function << <(N + 255) / 256, 256 >> >(dev_x, dev_y); | |
// GPU⇒CPUのデータコピー | |
cudaMemcpy(host_y, dev_y, N * sizeof(float), cudaMemcpyDeviceToHost); | |
} | |
else { | |
// CPUで計算 | |
cpu_function(N, host_x, host_y); | |
} | |
int end = clock(); | |
// 計算が正しく行われているか確認 | |
float sum = 0.0f; | |
for (int j = 0; j < N; j++) { | |
sum += host_y[j]; | |
} | |
std::cout << sum << std::endl; | |
// 最後に計算時間を表示 | |
std::cout << end - start << "[ms]" << std::endl; | |
return 0; | |
} |
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