Explain contiguous memory allocation

2 years ago
Operating System

⦁    In contiguous memory allocation, all the available memory space remain together in one place. It means freely available memory partitions are not scattered here and there across the whole memory space.
⦁    In the contiguous memory allocation, both the operating system and the user must reside in the main memory. The main memory is divided into two portions one portion is for the operating and other is for the user program.
⦁    In the contiguous memory allocation when any user process request for the memory a single section of the contiguous memory block is given to that process according to its need. We can achieve contiguous memory allocation by dividing memory into the fixed-sized partition.
⦁    A single process is allocated in that fixed sized single partition. But this will increase the degree of multiprogramming means more than one process in the main memory that bounds the number of fixed partition done in memory. Internal fragmentation increases because of the contiguous memory allocation.

Fixed sized partition:

In the fixed sized partition the system divides memory into fixed size partition (may or may not be of the same size) here entire partition is allowed to a process and if there is some wastage inside the partition is allocated to a process and if there is some wastage inside the partition then it is called internal fragmentation.

Advantage:

Management or book keeping is easy.

Disadvantage:

Internal fragmentation

Variable size partition:

In the variable size partition, the memory is treated as one unit, space allocated to a process is the same as required, and the leftover space can be reused again.

Advantage:

There is no internal fragmentation.

Disadvantage:

Management is very difficult as memory is becoming purely fragmented after some time.

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Sanisha Maharjan
Jan 14, 2022
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