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Combining Two Computer Performance Laws 

Paper title: Integrating Amdahl-Like Laws and Divisible Load Theory


  • Yang Cao, PhD student
  • Fei Wu, PhD alumni
  • Thomas Robertazzi


Parallel Processing Letters, vol 31, no.2, June 2021

Novel Technical Contribution

Amdahl’s Law relating the degree of parallelism in a computer system with the performance improvement that results was first proposed in 1967.  Its persistence in thought on computers surprised even the inventor.  The concept of loads that are divisible/partitionable was first studied extensively in 1988.  This is the first paper to the author’s knowledge that relates the two ideas directly.

Societal Contribution

We have all benefited from dramatic improvements in computer performance over the years.  Thus a study of computer performance is a worthwhile and very practical endeavor. 


A simple means of integrating the characteristics of networked processors under divisible loads into Amdahl’s Law is presented.  Amdahl’s Law serves as an upper bound to these speedup results.  Amdahl’s Law with divisible load processors included serves as an upper bound to speedup for any model taking into consideration more detailed peculiarities of real systems such as the overhead of task creation, synchronization, resource contention and memory issues.