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» Basic CS » Operating System

Essay Question▾

Describe in Detail

Discuss two problems of memory management.

Explanation

  • 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:

  • 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.