Symmetrical (Tightly-Coupled) Multiprocessors

Symmetrical multiprocessors (SMP) marked their existence during 1960s in the high- end mainframe space compelled by the requirement of scalability. Scalability is a property that allows to a system to adapt itself to the size of the problem to be handled. The processing capability of an SMP is adjusted by installing additional processors, until the requirements are met. This is beneficial for the customer as it allows increasing the capabilities of an installed system by the simple addition of processor modules, which distributes the workload among all the installed processors. The SMP approach is an economic way of implementing a range of systems. The power of various models in the range is characterized by the capabilities of the processors used, and also by the maximum number of processors that can be installed. SMPs are also known as tightly-coupled multiprocessors due to the close connection between the processors in the system. This chapter reviews symmetrical multiprocessors, its hardware limitations, software aspects, and SMP oriented operating systems.