并行程序：如何找到瓶颈（CPU绑定线程）

I have written a parallel program using OpenMP. It uses two threads because my laptop is dual core and the threads do a lot of matrix operations, so they are CPU bound. There is no data sharing among the threads. A single instance of the program runs quite fast. But when I run multiple instances of the same program simultaneously, the performance degrades. Here is a plot:I have written a parallel program using OpenMP.