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Fixed Workload Model

Amdahl's Law revised:

• Assumption: problem size fixed.
  • Sequential and parallelizable fraction.
  • Total work W = W_s+W_p.
• Goal: minimize computation time.

  S_n <=W_s + W_p/W_s + W_p/n <= W_s + W_p/W_s = 1/f.

• Applies when there are absolute constraints for solution time
  • Weather prediction.
  • Financial transactions.

For not perfectly scalable algorithms, efficiency eventually drops to zero!