Using Linked Lists for Dynamic Memory Management in Operating Systems

Explore the efficient use of linked lists in managing dynamic memory allocation in operating systems. This tutorial explains how linked lists track free and allocated memory partitions, facilitate efficient allocation and deallocation, and enable merging of adjacent free blocks for optimized memory utilization.

Using Linked Lists for Dynamic Memory Management

Linked Lists for Tracking Memory Partitions

In dynamic memory allocation, where the size of memory partitions can vary, using a linked list is an efficient way for the operating system to keep track of both free and allocated partitions. A linked list is a linear data structure where elements (nodes) are connected using pointers. Each node in the list represents a memory partition. Using a linked list makes it easy to add, remove, and manage partitions as processes are created and terminated.

Linked List Node Structure

Each node in the linked list representing a memory partition typically has three fields:

• Flag bit: Indicates whether the partition is free (a hole) or allocated to a process.
• Starting index: The starting memory address of the partition.
• Ending index: The ending memory address of the partition.

Adding New Partitions

When a partition is freed, the OS can efficiently merge it with adjacent free partitions. To add a new node to the linked list, the operating system must find the correct position to insert the node, so that the linked list is kept sorted according to starting index of the partitions. Inserting the node in ascending order of the starting indices simplifies searching and merging operations.

Using Doubly Linked Lists

Employing a doubly linked list (where each node points to both its previous and next node) improves performance. This is because it allows the OS to easily traverse the list in either direction. This is particularly useful when searching for a suitable location for a new partition or merging free blocks.