Question

A Suppose a pipelined 3 GHz processor runs instructions which contain 20% branch instructions (they branch to a non-sequential part of the code).

a) If there is no branch prediction in a pipeline, what is the CPI of the system if each stage takes 1 cycle and there is a 6 cycle penalty (related to re-filling the pipeline) for each time it branches?

b) If we are able to use branch prediction and are correct 90% of the time, what is the new CPI of the system?

Answer 1