Basic CS-Operating System [Redpine Infotech Placement]: Sample Questions 1 - 1 of 4

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Question 1

Operating System

Describe in Detail


Discuss two problems of memory management.


  • Memory management is the function of an operating system which handles or manages primary memory and moves processes back and forth between main memory and disk execution.
  • It tracks each and every memory location.
  • Checks how much memory is allocated to process.
  • Decides which process will get memory at what time.

Problems on Memory Management

  • Memory fragmentation
  • Interaction with paging

Memory Fragmentation:

  • Processes are loaded and removed from memory but the free memory space is broken into little pieces.
  • After sometime processes cannot be allocated to memory blocks considering their small size and memory blocks remain unused.
  • This problem is known as fragmentation.

    Two Types of Fragmentation

  • External fragmentation
    • Total memory space is enough to satisfy a request or to reside a process in it, but it is not contiguous, so it cannot be used.
  • Internal fragmentation
    • Memory block assigned to process is bigger.
    • Some portion of memory is left unused, it cannot be used by another process.


  • Paging is a memory management technique in which process address space is broken into blocks of the same size called pages
  • The size of the process is measured in the number of pages.
  • Main memory is divided into small fixed-sized blocks of memory called frames and the size of a frame is same as that of a page for optimum utilization of the main memory and to avoid external fragmentation.

Advantages of paging

  • Paging reduces external fragmentation.
  • Paging is simple to implement and assumed as an efficient memory management technique.

Disadvantage of paging

  • Page table requires extra memory space, so may not be good for a system having small RAM.

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