Kernel Data Structures in Operating System

There are following data structure in operating system is used

Lists, Stacks, and Queues

An array is a simple data structure in which each element can be accessed directly. For example, main memory is constructed as an array. If the data item being stored is larger than one byte, then multiple bytes can be allocated to the item, and the item is addressed as item number × item size. But what about storing an item whose size may vary? And what about removing an item if the relative positions of the remaining items must be preserved? In such situations, arrays give way to other data structures

The most common method for implementing this structure is a linked list, in which items are linked to one another. Linked lists are of several types:

  • In a singly linked list, each item points to its successor
  • In a doubly linked list, a given item can refer either to its predecessor or to its successor
  • In a circularly linked list, the last element in the list refers to the first element, rather than to null

A stack is a sequentially ordered data structure that uses the last in, first out (LIFO) principle for adding and removing items, meaning that the last item placed onto a stack is the first item removed. The operations for inserting and removing items from a stack are known as push and pop, respectively. An operating system often uses a stack when invoking function calls. Parameters, local variables, and the return address are pushed onto the stack when a function is called; returning from the function call pops those items off the stack.

A queue, in contrast, is a sequentially ordered data structure that uses the first in, first out (FIFO) principle: items are removed from a queue in the order in which they were inserted. There are many everyday examples of queues, including shoppers waiting in a checkout line at a store and cars waiting in line at a traffic signal. Queues are also quite common in operating systems—jobs that are sent to a printer are typically printed in the order in which they were submitted


A tree is a data structure that can be used to represent data hierarchically. Data values in a tree structure are linked through parent–child relationships. In a general tree, a parent may have an unlimited number of children

Hash Functions and Maps

A hash function takes data as its input, performs a numeric operation on this data, and returns a numeric value. This numeric value can then be used as an index into a table (typically an array) to quickly retrieve the data. Whereas searching for a data item through a list of size n can require up to O(n) comparisons in the worst case, using a hash function for retrieving data from table can be as good as O(1) in the worst case, depending on implementation details. Because of this performance, hash functions are used extensively in operating systems.


A bitmap is a string of n binary digits that can be used to represent the status of n items. For example, suppose we have several resources, and the availability of each resource is indicated by the value of a binary digit: 0 means that the resource is available, while 1 indicates that it is unavailable (or vice-versa).

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