Question

Relying on a subset of the performance equation (cpu execution time is the only valid comparison data), one could select the lower performing processor while they are requiring the higher performing design. for this question, here are the two processors. p1 has a clock rate of 3.0 ghz, average cpi of 1.60, and requires execution of 4.2 x 10^9 instructions. p2 has a clock rate of 3.5 ghz, and average cpi of 2.00 and requires 4.0 x 10^9 instructions. based on cpu execution time, the only valid comparison, which processor is faster?

Answer 1

Time for p1 to execute the instructions is
.. (4.2*10⁹ i)*(1.6 c/i)/(3.0*10⁹ c/s) = 2.24 s

Time for p2 to execute the instructions is
.. (4.0*10⁹ i)*(2.00 c/i)/(3.5*10⁹ c/s) = 2.29 s

Processor p1 is faster by about 2%.