Partition Allocation Methods in Memory Management

Partition Allocation Methods:

In Partition Allocation Methods, when there is more than one partition is free available to accommodate a process’s request. A partition must be selected.`To choose a particular partition, a partition allocation method is most needed. A partition allocation method considers better if it avoids internal fragmentation.

Single Partition Allocation:

In this memory allocation method, the operating system resides in the low memory. The remaining memory treated as a single partition. This single partition is available for userspace. Only one job can be loaded in this user space.

Multiple Partitions Memory Management:

This method can be implemented in 3 ways. These are:
i. Fixed-equal Multiple Partitions Memory Management
ii. Fixed-variable Partitions Memory Management
iii. Dynamic Partitions Memory Management

Fixed-equal Multiple Partitions Memory Management:

In this memory management, the operating system occupies the low memory and the rest of the main memory is available for user space. The user space divides into fixed partitions. The partition sizes are depending on the operating system.

Fixed-variable Partitions Memory Management:

In this memory management, the user space of the main memory is divided into several partitions. But the partition sizes are different lengths. The operating system keeps a table indicating which partitions of memory are available and which are occupied.

Dynamic Partitions Memory Management:

To eliminate some of the problems with fixed partitions, an approach known as Dynamic Partitions. In this method, partitions are created dynamically. So that each process loads into a partition of the same size as that process.

First fit:

Allocate the partition that is big enough, searching can start either from low memory or high memory. We can stop searching as soon as we find a free partition that is large enough.

Advantages of the First fit:

1. It is generally faster than the Worst fit.
2. It is better than the Worst fit in terms of decreasing time and storage utilization.

Best fit:

Allocate the smallest partition that is big enough (or) select a partition which had the least internal fragmentation.

Worst fit:

Search the entire partitions and select a partition which is the largest of all. Select a partition that had the maximum internal fragmentation.

Next fit:

Next fit is similar to the first fit. But it’ll search for the first sufficient partition from the last allocation point.