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2 votes
2 votes

A virtual memory system uses $FIFO$ page replacement policy and allocates a fixed number of frames to the process. Consider the following statements
 

M: Increasing the number of page frames allocated to a process sometimes increases the page fault rate.
N: Some programs do not exhibit locality of reference.

Which one of the following is true?

  1. Both $M$ and $N$ are true and $N$ is the reason for $M$.
  2. Both $M$ and $N$ are true but $N$ is not the reason for $M$.
  3. Both $M$ and $N$ are false.
  4. $M$ is false, but $N$ is true.
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1 Answer

7 votes
7 votes
  • M is true. This anomaly is called Bélády’s anomaly.
    • In some page replacement policies, on  increasing the number of page frames, number of page faults may increase.
    • common in FIFO approach.
  • Reason for M: when you have more pages, recently requested pages can remain at the bottom of the FIFO queue longer.
  • N is true. Locality of reference occurs because of the style of programming.

    • Same item may be accessed more than once.
    • Related data are stored in consecutive locations in storage.
    • Once a loop or subroutine is entered, there may be repeated references to a small set of instructions or data (cluster).
    • But we can write code without any features said before. hence N is true
  • But N is Not the reason for M

Answer is B

Answer:

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