Why one page table per process

operating-system os161
user308553 picture user308553 · Nov 29, 2011 · Viewed 13.8k times · Source

At first I thought there is only one page table for the whole system. But there are actually one page table per process? What is the point of having multiple page table instead of one page table.

I am implementing part of os161

Answer

Alexey Frunze picture Alexey Frunze · Nov 29, 2011

A page table usually has a fixed number of entries and therefore describes only a portion of the entire virtual address space. This is why you need multiple of them to cover the entire address space. Now, in many OSes processes have individual (in other words, not shared with others) virtual address spaces, which helps to protect processes from one another. This is another reason for having multiple page tables.

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