Assume you have an instruction cache miss rate of 4 and a da

Assume you have an instruction cache miss rate of 4%, and a data cache miss rate of 2%. The miss penalty is 100 cycles. You have a program that is 25% load-store instructions, with a base CPI of 1. What will its CPI be including cache misses?

Solution

Given miss penalty is 100 cycles

Given that I-cache miss rate is 2%   

so instruction cache can be calculated by using = I-cache * misspenality

0.02 * 100 =2

Given that D-cache miss rate is 4% and the program contains 25% Load-Store instructions

Hence data cache is given by = number of Load-store instructions * D-cache miss rate * misspenality

=0.25*0.04*100=4

Now given that the base CPI is 1

Hence CPI is given as =I-cache + D-cache + CPI base

= 2+4+1

=7

And here Ideal CPU is given by 7/2 =3.5 times faster