Question

In the context of operating systems, which of the following statements is/are correct with respect to paging?

• A. Paging helps solve the issue of external fragmentation.
• B. Page size has no impact on internal fragmentation.
• C. Paging incurs memory overheads.
• D. Multi-level paging is necessary to support pages of different sizes.

Hint:

Paging removes external fragmentation but introduces internal fragmentation and page table overheads.

Answer 1

The Correct Option is A, C

Step 1: External fragmentation.
Paging divides physical memory into fixed-size frames and processes into pages of the same size.

Since any page can be placed into any available frame, there is no requirement for contiguous memory allocation. Hence, paging eliminates external fragmentation.

Therefore, statement (A) is correct.

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Step 2: Internal fragmentation.
Internal fragmentation arises because a process may not completely fill its last allocated page.

The amount of this unused space depends directly on the page size. Larger page sizes can lead to more wasted space.

Hence, page size does affect internal fragmentation, making statement (B) incorrect.

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Step 3: Memory overhead.
Paging requires page tables to maintain the mapping between virtual pages and physical frames.

These page tables consume additional memory, introducing memory overhead.

Therefore, statement (C) is correct.

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Step 4: Multi-level paging.
Multi-level paging is designed to reduce the memory required for page tables by allocating them hierarchically.

It is not meant to support multiple page sizes. Hence, statement (D) is incorrect.

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Final Conclusion:
The correct statements are (A) and (C).