A particular parallel program computation requires 100 seconds... 20% strictly sequential... theoretical elapsed time on 2 CPUs and 4 CPUs?
- A. 55 and 45 seconds
- B. 80 and 20 seconds
- C. 75 and 25 seconds
- D. 60 and 40 seconds
Answer: D. 60 and 40 seconds
Explanation: Amdahl's law application. T = 100. Seq = 20s. Par = 80s. \n2 CPUs: T2 = 20 + 80/2 = 20 + 40 = 60s. \n4 CPUs: T4 = 20 + 80/4 = 20 + 20 = 40s.