There are five classes of instructions (A, B, C, D and E) in the instruction set. The processor has a clock rate of 4 GHz. The following table shows the CPI and the percentage of instructions executed by each class for a given program.
Class CPI % Instructions
A 1 30%
B 2 10%
C 3 10%
D 3 30%
E 5 20%
(a) Compute the average CPI.
(b) If 10 billion instructions were executed, what is the execution time in seconds?
(c) What percent of the execution time is used by each class of instructions?
(d) When you run the program, it takes 15 seconds to complete. What percentage of time the program is running on the CPU, and the percentage of time it is waiting?
(e) A newer processor reduces the CPI of class D instructions to just 1 cycle and of class E to just 2 cycles. It uses a faster 5 GHz clock. What is the new average CPI and the speedup of running the program on the newer processor?