UGC NET CSE | November 2017 | Part 2 | Question: 50

Question

Which speed up could be achieved according to Amdahl's Law for infinte number of processes if $5\%$ of a program is sequential and the remaining part is ideally parallel?

• A. Infinite
• B. $5$
• C. $20$
• D. $50$

Comments

sir no question

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yes, I just created the format. Questions are to be added.

Answer 1

20. Is the obvious answer 1/.05

Answer 2

C:20

Speedup according to Amdahl's law is found as :

Speedup   =    1 / [ 1 - f1 - f2  + ..  +( f1 / S1) + ( f2/S2)  + ( f3/S3) .. ]

where f1 , f2 etc.  : fraction of enhancements

          S1 , S2 etc : Speedup corresponding to each fraction of enhancement

Here in question f=0.95

1-f=5%=0.05 and s=⚮

Then speedup=1/(0.05+(0.95/⚮))

                          =1/(0.05+0)=20