Multiple-Processor Scheduling

Scheduling becomes more difficult when several CPUs are installed since the OS needs to divide work among the CPUs to keep each one busy.

In general, there might exist different kinds of CPUs on the same computer (heterogeneous), or all the CPUs could be of the same type (homogenous). To keep things simple for the sake of this discussion, we assume that the CPUs are homogenous.

An operating system could exhibit asymmetric multiprocessing, in which one 'boss' CPU controls the other CPUs, which is pretty simple to implement.

Otherwise, it could use symmetric multiprocessing (SMP), in which each processor schedules its own jobs. Most moderns operating systems use symmetric multiprocessing.