Question

4. The below table shows four different processors P1, P2, P3, and P4 executing the same program with clock rates and average CPls as shown below. Answer the following showing all the steps. Processor Clock rate CP 1.0 GHz 4.0 GHz 3.0 GHz 2.0 GHz P1 3.0 P2 2.0 P3 1.5 P4 2.5 a. Which processor has the best performance in terms of execution time? (8 Points) b. If the program has 5000 instructions, what is the time spent on each processor (P1, P2, P3, and P4) executing the program. (8 Points)

Answer 1

CPU time = Instruction count x CPI x Clock cycle

Clock cycle = 1 / Clock rate

GHz = 10^9 Hz

IC is not given in first case so let it be a constant IC

a) P1 exection time = IC * 3 * 1/(1 * 10^9) = IC * 3 * 10^(-9)

P2 exection time = IC * 2 * 1/(4 * 10^9) =  IC * 5 * 10^(-10)

P3 exection time = IC * 1.5 * 1/(3 * 10^9) = IC * 5 * 10^(-10)

P4 exection time  =IC * 2.5 * 1/(2 * 10^9) = IC * 1.25 * 10 ^ ( -9)

P2 and P3 have same and lowest exection time so they will have best performance

b)

P1 exection time = 5000 * 3 * 1/(1 * 10^9) = 15 * 10^(-6)

P2 exection time = 5000 * 2 * 1/(4 * 10^9) =  25 * 10^(-7)

P3 exection time = 5000 * 1.5 * 1/(3 * 10^9) = 25 * 10^(-7)

P4 exection time  = 5000 * 2.5 * 1/(2 * 10^9) =62.5 * 10 ^(-7)