In the context operating systems, which of the following statements is/are…
2026
In the context operating systems, which of the following statements is/are correct with respect to paging?
1. Paging incurs memory overheads.
2. Paging helps solve the issue of external fragmentation.
3. Page size has no impact on internal fragmentation.
4. Multi-level paging is necessary to support pages of different sizes.
- A.
Only 1 and 4
- B.
Only 2
- C.
Only 1 and 2
- D.
All
Attempted by 4 students.
Show answer & explanation
Correct answer: C
Concept: Paging divides physical memory into fixed-size frames and logical memory into equal-size pages, mapping each process page to any free frame through a per-process page table.
Because every frame is the same size, any free frame can hold any page, so paging removes external fragmentation entirely; but a process's last page usually is not fully used, so internal fragmentation up to almost one frame still occurs, and it grows with a larger frame size. The frame-to-page mapping is stored in a page table that itself occupies extra memory beyond what the process needs -- this is the memory overhead of paging. Multi-level paging exists to shrink one very large page table (built for a large logical address space) into a hierarchy of smaller tables -- that is a different concern from a system supporting more than one page size, so multi-level paging is not necessary for that.
Applying this to each statement:
Statement | Verdict | Why |
|---|---|---|
1. Paging incurs memory overheads | Correct | Every process needs its own page table held in memory, which is overhead beyond the process's actual data. |
2. Paging solves external fragmentation | Correct | Fixed, equal-size frames mean any free frame fits any page, so memory never fragments into unusable external gaps. |
3. Page size has no impact on internal fragmentation | Incorrect | Internal fragmentation is bounded by the frame size, so a larger page size directly increases the worst-case internal fragmentation. |
4. Multi-level paging is necessary to support pages of different sizes | Incorrect | Multi-level paging's role is to keep the page table itself small for a large address space by splitting one big table into a hierarchy of smaller tables; that is a different problem from supporting multiple page sizes, so multi-level paging is not necessary for it. |
Cross-check: this matches the standard trade-off of fixed-size allocation -- external fragmentation disappears whenever allocation units are uniform, while internal fragmentation appears whenever the last unit is only partially used, exactly as pages/frames behave.
Hence, statements 1 and 2 are correct.