A particular parallel program computation requires 100 seconds when executed…
2013
A particular parallel program computation requires 100 seconds when executed on a single CPU. If 20% of this computation is strictly sequential, then theoretically the best possible elapsed times for this program running on 2 CPUs and 4 CPUs respectively are
Answer: D. 60 and 40 seconds — According to Amdahl's Law, execution time T_N = S + P/N. Given 100s total with 20% sequential, S = 20s and P = 80s. For 2 CPUs: T_2 = 20 + 80/2 = 60s. For 4…
- A.
55 and 45 seconds
- B.
80 and 20 seconds
- C.
75 and 25 seconds
- D.
60 and 40 seconds
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Correct answer: D
According to Amdahl's Law, execution time T_N = S + P/N. Given 100s total with 20% sequential, S = 20s and P = 80s.
For 2 CPUs: T_2 = 20 + 80/2 = 60s.
For 4 CPUs: T_4 = 20 + 80/4 = 40s.
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