ISRO | ISRO CS 2013 | Question 55

In a 64-bit machine, with 2 GB RAM, and 8 KB page size, how many entries will be there in the page table if it is inverted?
(A) 2¹⁸
(B) 2²⁰
(C) 2³³
(D) 2⁵¹

Answer: (A)
Explanation: Generally OS maintains a separate pagetable for every process and these pagetables consume a substantial amount of memory whereas an Inverted pagetable stores the paging information of all the processes in a single page table. A simple inverted table stores one page entry per physical page(frame) and so there is a less memory overhead.

Memory size = 2 GB = 231
Page size = 8 KB = 213
Number of pagetable entries in inverted pagetable
= 231/213 =  218

So, option (A) is correct.

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