我想通过部分简单代码比较循环性能与openmp。但结果是错误的。OpenMP for循环导致错误结果
我已经使用减少来避免竞争条件,但从来没有工作。
这里是我的代码:感谢您的任何建议
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感谢您的通知。但添加“;”后为延迟循环。结果仍然错过匹配。 –
我手工计算的结果是49995000 和sumNoMP = 49992896 sum = 49994736 ..... –