Exercise 2: Consider two different processors, P1 and P2 executing a program having 5 billion (5109) instructions - P1 has a 2.5GHz clock rate and a CPI of 1.5. - P2 has a 3.5GHz clock rate and a CPI of 1.7. a) Which processor is faster, and by how much? P1:2.5GHz/1.5=5109 instructions per second P2:3.5GHZ/1.7=5109 instructions per second So P1 has the faster processor b) We are trying to reduce the CPU time of P1 by 20% but this leads to an increase of 25% in the CPI. What clock rate should we have to get this time reduction? CPU time =( Num of instructions CPI)/( Clock rate ) So if we want to reduce the CPU time by 20%, and CPI increases by 25%, CPU time 0.7=( Num of instructions CPI1.2)/( New Clock rate ) New clock rate = clock rate 1.2/0.7=1.71 clock rate New clock rate for each Processor : P1: 2.5GHz1.71=4.27GHz