Tuesday, 3 October 2017

NET 1

CBSE NET JUNE 2012 PAPER III

Suppose that a given application is run on a 64-processor machine and that 70 percent of the application can be parallelized. Then the expected performance improvement using Amdahl’ s law is

(A) 4.22 
(B) 3.22 
(C) 3.32 
(D) 3.52

Ans:-B

Explanation:-
According to Amdahl's law, in case of parallelization,if P is the proportion of the program that can be made parallel, then (1-P) is the proportion that cannot be parallelized. Then the maximum speedup that can be achieved by using N processor is, S(N)=1/(1-P)+P/N where N refers to the no of processors, and P refers to the proportion that can be parallelized. 

In the question above, no of processor, N=64
The proportion of the program that can be made parallel, P = 70%=0.7

So, substituting in the formula, we get, 1/(1-0.7)+0.7/64=1/0.3+0.0109375=1.0.310975
=3.215
=3.22

Therefore, the option is B.

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