Performance
The speedup of a program as a result of parallelization is given by Amdahl's law. Amdahl's Law states that potential program speedup is defined by the fraction of code (P) that can be parallelized: 1/(1-P)
If the code cannot be broken up to run over multiple processors, P = 0 and the speedup = 1 (no speedup). If it is possible to break up the code to be perfectly parallel then P = 1 and the speedup is infinite (in theory, although other factors such as scalability and complexity limit this possibility). Thus, there is an upper bound on the usefulness of adding more parallel execution units.
Gustafson's law is a law closely related to Amdahl's law but doesn’t make as many assumptions and tries to model these factors in the representation of performance. The equation can be modelled by S(P) = P − α * (P − 1) where P is the number of processors, S is the speedup, and α the non-parallelizable part of the process.
Read more about this topic: Distributed GIS
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