When segmentation and paging are both being used, as in MULTICS, first the segment descriptor must be looked up, then the page descriptor. Does the TLB also work this way, with two levels of lookup?

Explanation:

Segmentation with pagination tries to combine the best of the two previous schemes.

Segmentation provides direct support to the process regions and pagination allows better use of memory and a basis for building a virtual memory scheme.

A segment consists of a set of pages and, therefore, does not have to be contiguous in memory.

The MMU uses a segment table, such that each entry in the table points to a page table.

It requires a more complex hardware

The Multics system solved external fragmentation and long search times by page segments.

This solution differs from pure segmentation in that the entries in the segment table do not contain the base address of the segment, rather they contain the base address of the page table for this segment.