AMP

Asymmetric Multiprocessing

In an asymmetric multiprocessing system (AMP), not all CPUs are treated equally; for example, a system might allow (either at the hardware or operating system level) only one CPU to execute operating system code or might allow only one CPU to perform I/O operations. Other AMP systems would allow any CPU to execute operating system code and perform I/O operations, so that they were symmetric with regard to processor roles, but attached some or all peripherals to particular CPUs, so that they were asymmetric with respect to the peripheral attachment. Asymmetric multiprocessing was the only method for handling multiple CPUs before symmetric multiprocessing (SMP) was available. It has also been used to provide less expensive options on systems where SMP was available. Additionally, AMP is used in applications that are dedicated, such as embedded systems, when individual processors can be dedicated to specific tasks at design time.

Multiprocessing is the use of more than one CPU in a computer system. The CPU is the arithmetic and logic engine that executes user applications. With multiple CPUs, more than one set of program instructions can be executed at the same time. All of the CPUs have the same user-mode instruction set, so a running job can be rescheduled from one CPU to another.