Question

Suppose a program contains 500 million instructions to execute on a processor running on 2.2 GHz. Half of the instructions takes 3 clock cycles to execute, where rest of the instructions take 10 clock cycle. What is the execution time of the program

Answer 1

Answer:

1.48 s

Explanation:

Number of instructions = 500 million = 500 * 10⁶

clock rate = 1 / 2.2 GHz = 1 / (2.2 * 10⁹ Hz) = 0.4545 * 10⁻⁹ s

We need to compute the clocks per instruction (CPI)

The CPI = summation of (value * frequency)

CPI = (50% * 3 clock cycles) + (50% * 10 clock cycles)

CPI = (0.5 * 3) + (0.5 * 10) = 1.5 + 5 = 6.5

Execution time = number of instructions * CPI * clock rate

Execution time = 500 * 10⁶ * 6.5 * 0.4545 * 10⁻⁹ =1.48 s