ISRO CSE 2018 | Question: 20

Question

Determine the number of page faults when references to pages occur in the order $1,2,4,5,2,1,2,4.$ Assume that the main memory can accommodate $3$ pages and the main memory already has the pages $1$ and $2,$ with page $1$ brought earlier than page $2.$ (assume LRU i.e., Least-Recently-Used algorithm is applied)

• A. $3$
• B. $4$
• C. $5$
• D. None of the above

Comments

sorry bro my bad...option B is correct

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Why the answer is D? I think it should be B as it is given that 1,2 are already present in the main memory.

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ans should be 4.

page fault at 4,5,1,4

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@MRINMOY_HALDER I am getting same 

Answer 1

Option B. 4 page faults will happen.

1(hit), 2(hit), 4(miss), 5(miss), 2(hit), 1(miss), 2(hit), 4(miss).

Answer 2

Answer is (B) 4

Answer 3

The main memory already has the pages $1$ and $2$, with page $1$ brought earlier than page $2.$ It means $1,2$  is ${\color{Magenta}{\textbf{not}}}$ a page fault.

$1,2,4,5,2,1,2,4.$

Using LRU(Least -  Recently -  Used) algorithm we got $4$ page faults.

So, the correct answer is $(B).$

Comments

Nice.

how you made this figure?

I mean Latex or paintbrush?

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Microsoft paint.