Hi, I am quite new to OpenMP and I am trying to understand the concepts.
I have already used OpenMP instructions to parallelize a part of a Fortran program but I am not sure if I understand the function of the threads. By playing with the number of the threads (hardcoded inside the program) I see that there is no significant difference in speed. In fact, I would expect that using one thread would get me back to my serial setting (speed-wise). However, even with one thread, the code runs as fast as with 2,4, ..., 10 or more threads, and much faster than the serial version. After some point in thread number I see a slowdown.
Can anyone explain what all this means? The machine on which the code runs has 64 quad-core CPU's.