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(ASymmetric MultiProcessing) A multiprocessing design in which each CPU is assigned a particular program or part of a program that it executes for the duration of the session. Contrast with SMP, in which all the CPUs function as a single resource pool and take on whatever tasks need to be processed next. See MPP.


(Massively Parallel Processing or Massively Parallel Processor) A multiprocessing architecture that uses many processors and a different programming paradigm than the common symmetric multiprocessing (SMP) found in today's computer systems.

Self-Contained MPP Subsystems
Each CPU is a subsystem with its own memory and copy of the operating system and application, and each subsystem communicates with the others via a high-speed interconnect. In order to use MPP effectively, an information processing problem must be breakable into pieces that can all be solved simultaneously. In scientific environments, certain simulations and mathematical problems can be split apart and each part processed at the same time. In the business world, a parallel data query (PDQ) divides a large database into pieces. For example, 26 CPUs could be used to perform a sequential search, each one searching one letter of the alphabet. To take advantage of more CPUs, the data have to be broken further into more parallel groups.

In contrast, adding CPUs in an SMP system increases performance in a more general manner. Applications that support parallel operations (multithreading) immediately take advantage of SMP, but performance gains are available to all applications simply because there are more processors. For example, four CPUs can be running four different applications. See SMP.

MPP and SMP Architecture
In MPP operation, the problem is broken up into separate pieces, which are processed simultaneously. In SMP, CPUs are assigned to the next available task or thread that can run concurrently.

Integrated MPP and SMP
In the mid-1990s, Pyramid Technology combined MPP and SMP processing in its Reliant line. The SMP systems attached to a high-speed mesh interconnect that provided unusual flexibility, and the architecture was passed on to future systems after Fujitsu acquired the company. See Fujitsu Siemens. (Image courtesy of Pyramid Technology Corporation.)

ServerNet Mesh Interconnect
The orange disks, purple CPUs and green channels conceptually show the interconnections between CPU and I/O subsystems. ServerNet was a high-speed switch from Tandem when it was a thriving company. (Image courtesy of Tandem Computers.)

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