Question

A program executes 10 billion instructions. It executes on an Intel processor that has an average CPI of 1.5 and a clock frequency of 2 GHz. How many seconds does the program take to execute? What is the cycle time of this Intel processor? Assume that an AMD processor takes 6 seconds to execute the program. What is the speedup provided by the Intel processor, relative to the AMD processor

Answer 1

Given that

                         CPI = 1.5

                         Frequency = 2 GHz = 2 x 10⁹

$clock time = \frac {1}{frequency} = \frac {1}{2 \times 10^{9}} = 0.5 \times 10^{-9} = 0.5 ns$

$execution time = CPI \times Instruction count \times clock time (in secs)$

                                $= 1.5 \times (1 \times 10^{10}) \times (0.5 \times 10^{-9})$

                                $= 1.5 \times 1 \times 0.5 \times 10$

                               

Thus, the given program with 10 billion instructions would take 7.5 seconds to execute on a intel processor with a clock period of 0.5 ns.

$speed up = \frac {execution \: time\: with \: AMD \: processor}{execution \: time \: with \: Intel \:processor}$

                   $= \frac {6}{7.5} = 0.8$

                   Hence, the intel processor has shown a 0.8 times speed up relative to AMD processor.