Question

Suppose you have a program P and 90 percent of P can be parallelized, but 10 percent of P is inherently sequential and cannot be parallelized. Further suppose that the part of P that can be parallelized can run with equal load balancing (same load per processing element) on a parallel system with N processing elements. Express the performance of P as a simple equation in the independent variable N.

Answer 1

Answer:

Means no matter how many processors you use, speed up never increase from 10 times.

Explanation:

If a problem of size W has a serial component Ws,then performance using parallelism:

Using Amdahl's Law:

Tp = (W - Ws )/ N + Ws

Here, Ws = .1,

W - Ws = .9

Performance Tp = (.9 / N) + .1

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Speed Up = 1 / ( (.9 / N) + .1)

If N -> infinity, Speed Up <= 10

Means no matter how many processors you use, speed up never increase from 10 times.