What Is Compaction In OS?

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In the world of operating systems (OS), memory management plays a critical role in ensuring efficient utilization of computer resources. One essential aspect of memory management is “compaction,” a technique employed to optimize memory usage and enhance system performance. In this blog, we will explore the concept of compaction in operating systems, its purpose, implementation, and the benefits it offers in managing memory effectively.

What Is Compaction In OS?

In a computer system, memory is divided into multiple segments or blocks, with each block allocated to a specific process or program. Over time, as processes are executed and terminated, memory fragmentation can occur, leading to unoccupied gaps or small blocks of free memory scattered across the memory space. This fragmented memory layout can impact system performance, as it may become challenging to allocate sufficient continuous memory for large processes.

Compaction is a memory management technique that aims to address memory fragmentation by rearranging memory blocks to create larger contiguous blocks of free memory. By compacting or consolidating memory, compaction helps optimize memory utilization and alleviates the issues caused by memory fragmentation.

The Purpose Of Compaction:

The primary purpose of compaction is to ensure efficient memory allocation and deal with external fragmentation. External fragmentation occurs when there are numerous small blocks of free memory scattered across the memory space, making it challenging to allocate contiguous memory blocks for large processes. Compaction aims to resolve this issue by moving active processes closer together, freeing up larger blocks of continuous memory for new processes to use.

Implementation Of Compaction:

The implementation of compaction involves relocating active processes in memory to create larger free memory blocks. There are two main approaches to compaction:

  1. Dynamic Relocation: In dynamic relocation, the operating system identifies and relocates processes when external fragmentation is detected. This process is usually performed during low system activity to minimize disruptions.
  2. Partial Relocation: Partial relocation involves moving only selected processes to create larger free memory blocks. This approach reduces the overhead of complete compaction and is suitable for systems where full compaction is not necessary.

Benefits Of Compaction:

  1. Efficient Memory Utilization: Compaction optimizes memory allocation, ensuring that larger continuous memory blocks are available for new processes. This reduces memory wastage and enhances overall system performance.
  2. Reduced Memory Fragmentation: By consolidating memory and minimizing free memory gaps, compaction helps mitigate external fragmentation, allowing for smoother memory allocation.
  3. Enhanced Process Execution: With reduced memory fragmentation, the likelihood of memory allocation failures due to insufficient continuous memory decreases. This leads to improved process execution and reduced system crashes.
  4. Improved System Performance: By creating larger free memory blocks, compaction reduces the need for frequent memory allocation and deallocation operations. This results in more efficient memory access and, consequently, better system performance.


Compaction is a vital memory management technique in operating systems, designed to optimize memory usage and address memory fragmentation. By rearranging memory blocks to create larger continuous memory spaces, compaction enhances system performance, reduces memory wastage, and mitigates issues related to external fragmentation. As computer systems continue to evolve and handle increasingly complex tasks, the role of compaction in efficient memory management becomes more critical than ever, ensuring smooth and optimized functioning of modern operating systems.

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What Is Compaction Process In OS?

Compaction refers to combining of all the empty spaces together and processes. Compaction helps to solve the problem of fragmentation, but it requires a lot of CPU time. It moves all the occupied areas of storage to one end and leaves one large free space for incoming jobs, instead of numerous small ones.

What Is Compaction And Fragmentation In OS?

In an operating system, memory management plays a vital role in maximum CPU utilization, when space is allocated to a process there is some loss of memory(fragmentation) leads to inefficient use of memory, and to reduce this loss one of the techniques (compaction) is used to optimize memory space.

What Is Compaction In OS For In Internal Fragmentation?

Internal Fragmentation occurs when a process needs more space than the size of allotted memory block or use less space. External Fragmentation occurs when a process is removed from the main memory. Best Fit Block Search is the solution for internal fragmentation. Compaction is the solution for external fragmentation.

What Is The Purpose Of Memory Compaction?

Compaction moves “in-use” areas of memory to eliminate “holes” or unused areas of memory caused by process termination in order to create larger contiguous free areas. Some systems allow partitions to be swapped out to secondary storage to free additional memory.

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