Amdahl's Law

Amdahl's law, named after computer architect Gene Amdahl, is used to find the maximum expected improvement to an overall system when only part of the system is improved. It is often used in parallel computing to predict the theoretical maximum speedup using multiple processors.The generalized Amdahl's law is: where is a percentage of the instructions that can be improved (or slowed), is the speed-up multiplier (where 1 is no speed-up and no slowing), represents a label for each different percentage and speed-up, and is the number of different speed-up/slow-downs resulting from the system change.
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<parallel> (Named after Gene Amdahl) If F is the fraction of a calculation that is sequential, and (1-F) is the fraction that can be parallelised, then the maximum speedup that can be achieved by using P processors is 1/(F+(1-F)/P).
[Gene Amdahl, "Validity of the Single Processor Approach to Achieving Large-Scale Computing Capabilities", AFIPS Conference Proceedings, (30), pp. 483-485, 1967].
(2002-10-16)