Paging vs Segmentation

What are the differences between paging and segmentation?

  1. Paging

Paging is a memory management scheme that eliminates the need for contiguous allocation of physical memory. The process’s address space is divided into fixed-size blocks called pages, while physical memory is divided into fixed-size blocks called frames. Address translation in paging involves the following steps:

  • Logical Address Space: The logical address (generated by the CPU) is divided into a page number and a page offset.

  • Page Table Lookup: The page number is used as an index into the page table to find the corresponding frame number.

  • Physical Address Formation: The frame number is combined with the page offset to form the physical address in memory.

Advantages: - Eliminates external fragmentation. - Simplifies memory allocation. - Supports efficient swapping and virtual memory.

  1. Segmentation

Segmentation is a memory management technique where the memory is divided into variable-sized segments based on the logical divisions of a program, such as functions, objects, or data arrays.

Address translation in segmentation involves the following steps:

  • Logical Address Space: The logical address consists of a segment number and an offset within that segment.

  • Segment Table Lookup: The segment number is used as an index into the segment table to find the base address of the segment.

  • Physical Address Formation: The base address is added to the offset to form the physical address in memory.

Advantages: - Provides logical separation of different parts of a program. - Facilitates protection and sharing of segments. - Simplifies management of growing data structures.