Difference Between Paging and Segmentation in OS

In this post, we will understand the difference between paging and segmentation in operating system −

Paging

• The address space of a process is broken into fixed sized blocks.

• These fixed size blocks are known as pages.

• The operating system divides the memory blocks into pages.

• The size of the page is determined based on the memory available.

• This technique is quick in terms of memory access.

• It can cause internal fragmentation since some pages would not be utilized as much as the other pages.

• During the process of paging, a logical address is divided into page number and page offset.

• A page table is used to store the page data.

This is how Paging works −

Segmentation

• In this method, the address space of a process is broken down into varying sized blocks.

• These varying sized blocks are known as sections.

• A compiler is responsible in determining the size of the segment, the virtual address and the actual address.

• The size of the section is determined by the user.

• The process of segmentation is slower in comparison to paging.

• It can result in external fragmentation since some memory blocks may not be used at all.

• During this process, a logical address gets divided into a section number and a section offset.

• A segmentation table can be used to store the segmentation data.

This is how Segmentation techniques works with Segment Map Table −