A computer with a 64bit address uses a threelevel page table

A computer with a 64-bit address uses a three-level page table. Virtual addresses are split into a top-level page table field, a 17-bit second-level page table field, a 17-bit third-level page table field, and an 13-bit oset. How large are the pages and how many entries can the top-level page table maximally have?

Solution

Solution:

It is given that the offset is 13-bit ,therefore

it is clear that it will vary from 0 to 8191 (2¹³)

hence the page size will be 8192 i.e. 8K

To calculate the entries for the top-level page table, fist we will calculte the number of bits it will have.

As computer is using 64-bit address, therefore for three-level page table we get

13-bit top level

17-bit second level

17-bit third level

and

13-bit offset

now as the top level is having 14-bit , we get

2¹³ = 8192 enteries