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About memory management overview, implementation techniques, and page replacement algorithm

   Mar 13, 2024     2 min read

This article provides an overview of memory management, implementation techniques, and page replacement algorithms.

In this article, we are preparing an information processing article and this time we will look at memory management.

Memory management is an important part of the operating system, and various techniques and algorithms are used to determine how programs are stored in memory and to utilize memory space efficiently.

Let’s find out together.

Storage management overview

Memory management is responsible for storing data and instructions required when a program is executed and allocating memory space required for execution.

To manage this efficiently, we have the following goals:

  • Address space allocation: When a program is loaded into memory, it allocates an appropriate address space to prevent crashes or overflows.
  • Memory protection: Protects memory areas from being accessed by other programs or operating systems.
  • Efficient use of memory space: Minimizes unused memory space and allows multiple processes to run simultaneously in a multiprogramming environment.

Storage management implementation techniques

Storage management manages memory using a variety of implementation techniques. Key implementation techniques include:

  • Single fixed partition allocation: Memory is divided into multiple fixed sizes and allocated to processes. Each partition can only be used by one process and cannot be used by any other process.
  • Variable partition allocation: Dynamically partitions memory and allocates it to processes. Depending on the size of the process, you can allocate and free as much memory space as needed.
  • Paging: Memory is divided into fixed-sized pages, and processes are allocated in page units. This helps solve external fragmentation issues.
  • Segmentation: Memory is divided into segments, which are logical units, and processes are allocated by segment. A segment is a logical part of a program and consists of code, data, stack, etc.

Page replacement algorithm

Since all pages cannot be loaded into memory in the paging technique, only the pages that are needed are loaded and the pages that are not needed are stored in auxiliary memory.

When a page fault occurs, a page replacement algorithm must be used.

The main page replacement algorithms are as follows:

  • FIFO (First-In, First-Out): Replaces the page that came in first.
  • Least Recently Used (LRU): Replaces the page that has not been referenced in the longest time.
  • Least Frequently Used (LFU): Replace the least referenced pages.
  • OPT (Optimal): Replace pages that will not be used for the longest time in the future. Although this is an optimal algorithm in theory, it is difficult to implement in practice.

Conclusion

Memory management is one of the core functions of an operating system and has a significant impact on the speed and efficiency of program execution.

Managing it effectively helps improve system stability and performance.

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