Which speed up could be achieved according to Amdahl’s Law for infinite number…
2017
Which speed up could be achieved according to Amdahl’s Law for infinite number of processes if 5% of a program is sequential and the remaining part is ideally parallel ?
Answer: C. 20 — Amdahl's Law: the speedup with N processors is S(N) = 1 / (f_s + (1 - f_s)/N). Limit for infinite processors: as N → ∞ the parallel term vanishes, so the…
- A.
Infinite
- B.
5
- C.
20
- D.
50
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Correct answer: C
Amdahl's Law: the speedup with N processors is S(N) = 1 / (f_s + (1 - f_s)/N).
Limit for infinite processors: as N → ∞ the parallel term vanishes, so the maximum speedup is S_max = 1 / f_s.
Sequential fraction f_s = 5% = 0.05.
Maximum speedup S_max = 1 / 0.05 = 20.
Therefore the maximum achievable speedup with an infinite number of processors is 20.
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