Difference Between Fragmentation and Segmentation in OS (original) (raw)

Last Updated : 23 Jul, 2025

Memory management is an essential part of the operating system that concerns itself with the allocation, control, and release of memory resources. This is because every application that is executed will require some space for its data, code, and execution stacks, which also creates the need for appropriate strategies to address. Two main aspects of the concepts that have a primary influence on this process are considered to be fragmentation and segmentation. Fragmentation and segmentation are key terms that one should learn the meaning of so as to comprehend how operating systems strive to make the best use of memory while ensuring systems are still functional. This article provides a deeper understanding of both concepts.

What is Fragmentation?

Fragmentation, as the name suggests, is a process in which free memory space is broken into little pieces. In this, memory blocks cannot be allocated to processes due to their small size and such blocks remain unused. It usually occurs in dynamic memory allocation systems when many of the free blocks are too small to satisfy any request.

Example

For instance, if a program requests 10 MB, the OS will accept such a request and allocate 12 MB because of rounding off to the nearest allocation unit. When the program terminates, this block becomes a "hole" if not all 12 MB are reused efficiently.

Types of Fragmentation

**External Fragmentation: occurs every time a part of free memory is broken into tiny regions and is distributed around the system which makes it difficult to locate a consecutive region for new allocations.
**Internal Fragmentation: occurs when a fixed block memory is allocated to a process yet a fraction of it is required leading to space wastage in the blocks.

Advantages

Does not require a lot of work and there is easy implementation of dynamic memory allocation.
Variable-size allocation is possible hence the size of blocks does not have to be very rigid.

Disadvantages

If left unmanaged for long periods, this process can cause excessive memory wastage.
Sometimes, the insertion of compaction has to be employed in order to have the most efficient use of space, and this can be quite expensive in terms of the CPU.

What is Segmentation?

Segmentation, as name suggests, is basically a memory management technique that supports user’s view of memory and is also known as non-contiguous memory allocation technique. In this, each process is divided into number of segments and detail about each segment can be stored in table that is known as segment table. It is basically a process that creates variable-sized address spaces in computer storage for related data. Segments are not fixed in size.

Example

A program can be split into three segments: code, data, and stack. Each segment can be independently allocated in memory, and the operating system keeps track of these segments using a segment table.

Advantages

This provides both a more rational and more practical way of handling memory.
Can also lead to external fragmentation principally if segments are allocated and de-allocated at almost the same time.

Disadvantages

Hard to implement as it requires the use of segment tables, and a segment management algorithm.
May also lead to external fragmentation if segments are allocated and deallocated frequently.

Difference Between Fragmentation and Segmentation in OS

Fragmentation	Segmentation
In this, storage space is used inefficiently that in turn reduce capacity and performance.	In this, memory is divided into variable size parts usually known as segments.
Types of fragmentation includes internal and external fragmentation.	Types of segmentation includes virtual memory and simple segmentation.
Its main purpose is to help operating system use the available space on storage device.	Its main purpose is to give user’s view of process.
It reduces efficiency in memory management.	It simply allows for better efficiency in memory management.
In this, memory blocks are not used i.e., it remains unused.	It usually works a memory management technique to execute processes.
It is generally associated with IP.	It is generally associated with TCP.
It is an unwanted problem that causes wastage of memory and inflexibility.	Its advantages include less overhead, larger segment size than actual page size, no internal fragmentation, etc.

Conclusion

Segmentation and Fragmentation are ways of managing memory for the processes in the operating systems that involve different strategies. Fragmentation describes other forms that result from uncommitted spaces being left, and this leads to resource waste while. Segmentation is placing logical divisions on memory space so as to make program units more manageable. Both methods include frequency control and restraints and specific reverses understanding to avoid any significant loss of resources.