Assume that there are five instruction types in an ISA which

Assume that there are five instruction types in an ISA, which are ALU, Load Store, Branch, and Logical, respectively. For a specific program P, each instruction type\'s frequency and their individual CPI are specified in the following table. What is the overall CPI (clock cycle per instruction) for the program. What is the new overall CPI if a better data cache reduced the average load time to 2 cycles? How much faster would the machine be? What is the new overall CPI if two ALU instructions could be executed at the same time? How much faster would the machine be?

Solution

I. CPI stands for average number of CYCLES PER INSTRUCTION.

  The overal CPI for the program is (1*40+5*15+3*15+2*40+1.5*10) / 100 = 2.15

CPI = 2.15