Question

page tables for large processes can easily take up a large amount of physical memory. one, proposed, solution to this problem is to use a multilevel page map table and put some portions in virtual memory. Explain how you would implement that. In your answer, please, specifically, discuss how a virtual address would be converted to a physical address.

Answer 1

Here there is only one page table in the level 1 and it contains 2^10 page entries and the correct page entry is identified by the level 1 address in the virtual address i.e., x here.

In level 2 , there are 2^10 page tables each corresponding to the one entry in the level 1 and each containing 2^10 page entries.

With the help of address pointed by the level 1 and level 2( in the virtual address i.e., y) we go to correct page table and page entry in the level 3.

With the help of address of level3 in the Virtual address i.e.,z we get a address called A and the offset is same as the offset in the Virtual address i.e.,w.

So finally physical address is [AW].

Where ,
A is frame number
W is offset