Amdahl’s Law (contd.)
But the enhanced feature may not be used all the time. Let the fraction of the computation time when the enhanced feature is used be : F.
Let the speedup when enhanced feature is used be Se.
Now execution time with enhancement Xnew = Xold * (1-F) + Xold* F /Se
Then the overall speedup So is : Xold /Xnew = 1 /((1- F) + F/Se)