Multiprocessing

Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system.[1][2] The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There are many variations on this basic theme, and the definition of multiprocessing can vary with context, mostly as a function of how CPUs are defined (multiple cores on one die, multiple dies in one package, multiple packages in one system unit, etc.).

According to some on-line dictionaries, a multiprocessor is a computer system having two or more processing units (multiple processors) each sharing main memory and peripherals, in order to simultaneously process programs.[3][4] A 2009 textbook defined multiprocessor system similarly, but noting that the processors may share "some or all of the system’s memory and I/O facilities"; it also gave tightly coupled system as a synonymous term.[5]

At the operating system level, multiprocessing is sometimes used to refer to the execution of multiple concurrent processes in a system, with each process running on a separate CPU or core, as opposed to a single process at any one instant.[6][7] When used with this definition, multiprocessing is sometimes contrasted with multitasking, which may use just a single processor but switch it in time slices between tasks (i.e. a time-sharing system). Multiprocessing however means true parallel execution of multiple processes using more than one processor.[7] Multiprocessing doesn't necessarily mean that a single process or task uses more than one processor simultaneously; the term parallel processing is generally used to denote that scenario.[6] Other authors prefer to refer to the operating system techniques as multiprogramming and reserve the term multiprocessing for the hardware aspect of having more than one processor.[2][8] The remainder of this article discusses multiprocessing only in this hardware sense.

In Flynn's taxonomy, multiprocessors as defined above are MIMD machines.[9][10] As the term "multiprocessor" normally refers to tightly coupled systems in which all processors share memory, multiprocessors are not the entire class of MIMD machines, which also contains message passing multicomputer systems.[9]

  1. ^ Raj Rajagopal (1999). Introduction to Microsoft Windows NT Cluster Server: Programming and Administration. CRC Press. p. 4. ISBN 978-1-4200-7548-9.
  2. ^ a b Mike Ebbers; John Kettner; Wayne O'Brien; Bill Ogden (2012). Introduction to the New Mainframe: z/OS Basics. IBM. p. 96. ISBN 978-0-7384-3534-3.
  3. ^ "Multiprocessor dictionary definition - multiprocessor defined". www.yourdictionary.com. Archived from the original on 16 March 2018. Retrieved 16 March 2018.
  4. ^ "multiprocessor". Archived from the original on 16 March 2018. Retrieved 16 March 2018 – via The Free Dictionary.
  5. ^ Irv Englander (2009). The architecture of Computer Hardware and Systems Software. An Information Technology Approach (4th ed.). Wiley. p. 265. ISBN 978-0471715429.
  6. ^ a b Deborah Morley; Charles Parker (13 February 2012). Understanding Computers: Today and Tomorrow, Comprehensive. Cengage Learning. p. 183. ISBN 978-1-133-19024-0.
  7. ^ a b Shibu K. V. Introduction to Embedded Systems. Tata McGraw-Hill Education. p. 402. ISBN 978-0-07-014589-4.
  8. ^ Ashok Arora (2006). Foundations of Computer Science. Laxmi Publications. p. 149. ISBN 978-81-7008-971-1.
  9. ^ a b Ran Giladi (2008). Network Processors: Architecture, Programming, and Implementation. Morgan Kaufmann. p. 293. ISBN 978-0-08-091959-1.
  10. ^ Sajjan G. Shiva (20 September 2005). Advanced Computer Architectures. CRC Press. p. 221. ISBN 978-0-8493-3758-1.