**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.