This exercise examines the accuracy of branch predictors for

This exercise examines the accuracy of branch predictors for the following repeating pattern of branch outcomes: T, T, T, NT, T Suppose the pattern repeats for many times, the initial state of the predictor does not affect the accuracy much. What is the accuracy of always-taken predictor? What is the accuracy of always-not-taken predictor? What is the accuracy of a single-bit predictor? What is the accuracy of a two-bit predictor?

Solution

a) always taken = 4/5 = 0.8 = 80%

d) always not taken = 1/4 = 0.25 = 25%

c) approximately 80%