我想了解如何使用openmp进行多线程。 这里是我的代码:Openmp无法自动创建线程
#include <iostream>
#include <math.h>
#include <omp.h>
//#include <time.h>
//#include <cstdlib>
using namespace std;
bool isprime(long long num);
int main()
{
cout << "There are " << omp_get_num_procs() << " cores." << endl;
cout << 2 << endl;
//clock_t start = clock();
//clock_t current = start;
#pragma omp parallel num_threads(6)
{
#pragma omp for schedule(dynamic, 1000)
for(long long i = 3LL; i <= 1000000000000; i = i + 2LL)
{
/*if((current - start)/CLOCKS_PER_SEC > 60)
{
exit(0);
}*/
if(isprime(i))
{
cout << i << " Thread: " << omp_get_thread_num() << endl;
}
}
}
}
bool isprime(long long num)
{
if(num == 1)
{
return 0;
}
for(long long i = 2LL; i <= sqrt(num); i++)
{
if (num % i == 0)
{
return 0;
}
}
return 1;
}
的问题是,我想的OpenMP基于多少个核心都可以自动创建多个线程。如果我取出num_threads(6),那么它只使用1个线程,但omp_get_num_procs()正确输出64.
如何获得此工作?