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A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because

  1. It reduces the memory access time to read or write a memory location.

  2. It helps to reduce the size of page table needed to implement the virtual address space of a process

  3. It is required by the translation lookaside buffer.

  4. It helps to reduce the number of page faults in page replacement algorithms.

asked in Operating System by Veteran (59.6k points)
edited by | 2k views

2 Answers

+20 votes
Best answer

Option - > (B)

  1. It reduces the memory access time to read or write a memory location. -> No This is false. Actually because of multi level paging we increase no of memory accesses.

  2. It helps to reduce the size of page table needed to implement the virtual address space of a process -> This is true, In case of big virtual memory page, size of Page table can also be too huge to fit in single Page. So we do multi level paging.

  3. It is required by the translation lookaside buffer.-> Examiner was not being enough creative here, This is false & There is no relation. This option is just given for no reason !

  4. It helps to reduce the number of page faults in page replacement algorithms.-> This is false, we might increase no of page faults. (Due to second / thirrd level page not in memory here !) So this is false.

answered by Boss (42.9k points)
edited by
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nice explanation @Akash sir
+16 votes
B.

Which is a clear reason why we perform paging.

When the page table size increases we perform paging on the page table. Resulting in multi-level page table.
answered by Boss (19.7k points)
+11

See this question to see how drastically two level paging reduces size. Only 16KB. In multi-level paging, we do have entries for pages that are actually being used.

If we use Flat page table (Single page table) then we would need $2^{20} \times 4 = 4$MB of page table size. but after two paging only $16$KB would suffice.



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