我想通過部分簡單代碼比較循環性能與openmp。但結果是錯誤的。OpenMP for循環導致錯誤結果
我已經使用減少來避免競爭條件,但從來沒有工作。
這裏是我的代碼:感謝您的任何建議
void TestMP_1(){
float afValueTmp[MP_TEST_NUM] = { 0 }; // MP_TEST_NUM = 10000
float sum = 0, sumNoMP = 0;
float fDiff = 0;
double eTDiff = 0;
double t0 = 0;
double t1 = 0;
for (int i = 0; i < MP_TEST_NUM; i++)
{
afValueTmp[i] = i;
}
t0 = (double)getTickCount();
for (int i = 0; i < MP_TEST_NUM; i++)
{
for (int k = 0; k < MP_TEST_NUM; k++); // just for delay
sumNoMP += afValueTmp[i]; // equation 4
}
t0 = ((double)getTickCount() - t0)/getTickFrequency();
t1 = (double)getTickCount();
#pragma omp parallel for reduction(+:sum)
for (int i = 0; i < MP_TEST_NUM; i++)
{
for (int k = 0; k < MP_TEST_NUM; k++); // just for delay
sum += afValueTmp[i];
}
t1 = ((double)getTickCount() - t1)/getTickFrequency();
eTDiff = t0 - t1; // time improve
fDiff = sum - sumNoMP; // check result
printf("%.3f\n", eTDiff);
}
'for(int k = 0; k
@ Johnny Mopp感謝您的通知。但添加「;」後爲延遲循環。結果仍然錯過匹配。 –
我手工計算的結果是49995000 和sumNoMP = 49992896 sum = 49994736 ..... –