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Amdahl's Law

Description
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  • So, there is this notion (specially in parallel programming world) that all we have to do is keep adding processors to the problem and its going to get faster no matter what, which is incorrect. Amdahl’s Law is how we quantify that.

  • Use Amdahl’s Law when you want to speed up part of the program or only some instructions.

Formulla
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\( S = \frac{1}{(1 - P) + \frac{P}{N}} \)

where:

  • \( S \) is the overall speedup.
  • \( P \) is the fraction of the program that we enhanced.
  • \( N \) is speedup of the enhanced part.

Note: \( P \) is the % of original execution time that is affected by the enhancement.

References
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