Question

Consider the following page reference string: 1, 2, 3, 4, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2. Assuming demand paging with four frames, how many page faults would occur for the following replacement algorithms? • LRU replacement​

Answer 1

Explanation:

Express 0.134 bar in p/q form (only 3 and 4 have bar)

Answer 2

Answer:

There will be total of 9 page faults on using LRU replacement.

Explanation:

LRU(Least Recently Used ) Replacement Algorithm replace the page which is most least recently used with the new page.

Here in this question, demand paging is given with four frames.

So starting 4 frames i.e. ( 1, 2, 3, 4) will insert without any page fault.

After that for new page insertion, operating system will replace the least recently used page with the new one.

For inserting 5 ---> Frame 1 is replaced. (one page fault)

For inserting 3 ----> No page fault

For inserting 4 ----> No page fault

For inserting 1 -----> Frame 2 is replaced (second page fault)

In the similar way,

For last frame total of 9 page fault will occur.

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