In my program, I use nested parallelism. Using Microsoft's MSVC compiler on Windows system, I have achieved good performance. However, under the gcc compiler on Linux, the performance of nested parallelism seems to be relatively poor, and the completion time is about 40% worse than that of windows. My server has two physical CPUs, 48 cores and 96 threads, and I have six parallel sections outside. An obvious performance is that on Linux system, if I open more than 4 threads in the nested parallel, the system performance will decline sharply, but not on windows. Linux version is 3.10, CentOS 7, and GCC version is 4.8 1. So I wonder if there is something wrong with my settings, or the difference between gcc compiler and MSVC compiler, or the difference between Linux and windows system?How can I solve this problem? My code is as follows：
omp_set_dynamic(1);
omp_set_nested(1);
#pragma omp parallel sections
{
#pragma omp section
{
func()
}
#pragma omp section
{
func()
}
#pragma omp section
{
func()
}
#pragma omp section
{
func()
}
#pragma omp section
{
func()
}
#pragma omp section
{
func()
}
}
void func()
{
#pragma omp parallel for schedule(static) num_threads(4)
for(int k=0;k<1280000000;k++)
{
}
}
