Memory Management

A memory manager is responsible for keeping track of which parts of the memory are in use and which parts are not, so that they can be deallocated.

It is important to manage memory effectively for optimal system performance.

The MMU handles the mapping between logical (virtual) and physical memory.

Single tasking with overlay, fixed memory partitioning, and variable memory partitioning.

A technique to allow a process to be larger than the size of physical memory by keeping only instructions and data needed at any given time in memory.

New instructions are loaded into the space previously occupied by instructions that are no longer needed.

A process cannot take advantage of more memory if it is available, as the overlays are designed around a given amount of memory.

It divides the memory space into fixed-sized partitions, each of which may contain exactly one process.

It is bounded by the number of partitions.

The partition it occupied becomes available for another process.

It can lead to internal fragmentation.

Memory space is divided into variable-sized partitions, and a process is loaded wherever a large enough space is available.

First Fit, Best Fit, and Worst Fit.

It can lead to external fragmentation.

It happens when memory spaces are used in such a way that there are small pieces of memory left unused.

Too many small-sized free spaces exist that are not contiguous, making them unusable even if total free space is sufficient.

Through compaction, which shuffles all free memory spaces together to form a large, contiguous block.

It occurs when extra space is allocated to a process than it actually needs, and the leftover space cannot be used elsewhere.

Fixed partitioning.