If you'r CPU's are hyperthreading Xeon's it's perfectly
normal for you to see 4 CPU's.
As for the assigning of a task to a specific processor:
to the best of my knowledge that's impossible, I've
googled a bit and found only references in the Beowulf-
Howto that stated it's not possible (at the time of the
But really, Linux is very clever in CPU and memory
management, you probably should trust the OS ;)