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Consider a main memory with five page frames and the following sequence of page references: 3, 8, 2, 3, 9, 1, 6, 3, 8, 9, 3, 6, 2, 1, 3. Which one of the following is true with respect to page replacement policies First In First Out (FIFO) and Least Recently Used (LRU)?
  • a)
    Both incur the same number of page faults
  • b)
    FIFO incurs 2 more page faults than LRU
  • c)
    LRU incurs 2 more page faults than FIFO
  • d)
    FIFO incurs 1 more page faults than LRU
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
Consider a main memory with five page frames and the following sequenc...
LRU:
9-page faults:
FIFO:
9-page faults:
Hence LRU and FIFO will have 9-page faults.
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Most Upvoted Answer
Consider a main memory with five page frames and the following sequenc...
LRU:
9-page faults:
FIFO:
9-page faults:
Hence LRU and FIFO will have 9-page faults.
Free Test
Community Answer
Consider a main memory with five page frames and the following sequenc...
Page Replacement Policies: FIFO and LRU

Introduction:
Page replacement is an essential part of the memory management system in an operating system. When a process requests a page that is not present in the main memory, a page fault occurs, and the operating system needs to replace one of the existing pages to accommodate the new page.

Two commonly used page replacement policies are First In First Out (FIFO) and Least Recently Used (LRU). In this question, we are given a sequence of page references and need to analyze the number of page faults incurred by each policy.

Given Information:
Main memory has five page frames.
Sequence of page references: 3, 8, 2, 3, 9, 1, 6, 3, 8, 9, 3, 6, 2, 1, 3.

FIFO (First In First Out) Page Replacement Policy:
In the FIFO page replacement policy, the page that has been in the memory the longest is replaced. It follows a queue-like structure, where the page that arrived first is the first to be replaced.

LRU (Least Recently Used) Page Replacement Policy:
In the LRU page replacement policy, the page that has not been used for the longest period of time is replaced. It requires maintaining a list of pages in the memory and updating their usage information.

Analysis:
Let's analyze the given page reference sequence and calculate the number of page faults for each policy.

FIFO:
Initially, all page frames are empty.
- When page 3 is requested, it is loaded into an empty frame (Page Fault: 1).
- When page 8 is requested, it is loaded into another empty frame (Page Fault: 2).
- When page 2 is requested, it is loaded into a new frame (Page Fault: 3).
- When page 3 is requested again, it is already present in the memory (No Page Fault).
- When page 9 is requested, it is loaded into a new frame, replacing page 3 (Page Fault: 4).
- When page 1 is requested, it is loaded into a new frame, replacing page 8 (Page Fault: 5).
- When page 6 is requested, it is loaded into a new frame, replacing page 2 (Page Fault: 6).
- When page 3 is requested again, it is already present in the memory (No Page Fault).
- When page 8 is requested again, it is already present in the memory (No Page Fault).
- When page 9 is requested again, it is already present in the memory (No Page Fault).
- When page 3 is requested again, it is already present in the memory (No Page Fault).
- When page 6 is requested again, it is already present in the memory (No Page Fault).
- When page 2 is requested again, it is already present in the memory (No Page Fault).
- When page 1 is requested again, it is already present in the memory (No Page Fault).
- When page 3 is requested again, it is already present in the memory (No Page Fault).

Total number of page faults using FIFO: 6

LRU:
Initially, all page frames are empty.
- When page
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Consider a main memory with five page frames and the following sequence of page references: 3, 8, 2, 3, 9, 1, 6, 3, 8, 9, 3, 6, 2, 1, 3. Which one of the following is true with respect to page replacement policies First In First Out (FIFO) and Least Recently Used (LRU)?a)Both incur the same number of page faultsb)FIFO incurs 2 more page faults than LRUc)LRU incurs 2 more page faults than FIFOd)FIFO incurs 1 more page faults than LRUCorrect answer is option 'A'. Can you explain this answer?
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