Amdahl's law. The speedup of a program using multiple processors in parallel computing is limited by the sequential fraction of the program.
For example, if 95% of the program can be parallelized, the theoretical maximum speedup using parallel computing would be 20× as shown in the diagram, no matter how many processors are used. Amdahl's law, also known as Amdahl's argument,[1] 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 law is named after computer architect Gene Amdahl, and was presented at the AFIPS Spring Joint Computer Conference in 1967.
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