[Omp] Noob question about processors

[Terboven, Christian]

> So if I understand correctly, you mean that gcc/linux
> is not able to spread the tasks over 2 real cpu's and
> only puts the threads on one of those.
No. You can use your machine as if it has four physical processors.
What I was refering to was the problem that you cannot influence how
your threads are scheduled on the available processing units. I might be
wrong there if taskset behaves how Kay described, though that is not
what I experienced. I will look into this.


Thank you, Georg, for the link to PLPA. I will look into this as well.


> This would explain why I only obtain a speed up of 2 instead of 4.
You are expecting too much from Hyper-Threading.
If you restrict your program to just one physical CPU (using taskset)
you can see what Hyper-Threading can do for your program.



Kind regards,
Christian