Virtual Memory

Question

If i have a Reference string with S  and page fault as N . then what is number of page fault when we take reverse of string s^r ?

1)FIFO

2)LRU

3)MRU

4)OPTIMAL 

// i was given this question for 1 algorithm , but the i tried to find for all page replacement algorithm .

 

 

 

Answer 1

Arjun sir please kindly check this :)

// i can be wrong . i just tried it . it may happen that all relation ,ay be wrong and depends upon reference string only

Let us denote number of page fault with S = P1

let us denote number of page fault with S^r = P2

so according to me 

in case of fifo , p1 may or may not be equal to p2

in case of lru , p1= p2

in case of optimal p1=p2

in case of MFu p1 not equal to p2

Am i right sir ?

Comments

most frequently used and most recently used both are same ?

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No. Say is a page has been accessed 10 times and another page just 1 but was the last accessed one; then with LRU policy, the first one will get replaced.

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Arjun sir.m confused between MOST RECENTLY USED(MRU) & MOST FREQUENTLY USED(MFU) ?

It is right that MRU and LRU both are opposite but what about MFU ?