Communications between cores is perhaps most critical, because it can produce considerable overhead in some systems. Without special measures there is a quadratic dependence on the number of processors, so a multi-core system with four processors has about a tenfold increase in communications overhead compared with a single core. For eight processors that factor is 36, for 16 processors it is 136 and for 256 processors it is more than 32,000! A smart communications network structure is therefore essential for the system to perform any meaningful work.