What is a primary drawback associated with dynamic partitioning in memory…
2025
What is a primary drawback associated with dynamic partitioning in memory allocation?
- A.
Large amounts of unused space remain within allocated memory segments.
- B.
Fragmentation occurs as available memory is split into noncontiguous chunks.
- C.
Once a memory block is assigned, it cannot be adjusted to fit changing process sizes.
- D.
Memory cannot be allocated based on the process's exact memory needs.
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Correct answer: B
Dynamic partitioning allocates memory based on process needs, but over time creates external fragmentation where free space is split into noncontiguous chunks.
Note for more understanding
In Operating Systems, Dynamic Partitioning (or variable partitioning) was introduced to solve the main flaw of fixed partitioning: wasted space inside an allocated block (internal fragmentation). In this scheme, when a process arrives, the OS carves out a block of memory exactly equal to the size the process asks for.
The Problem: External Fragmentation
While this perfectly eliminates internal fragmentation, it introduces external fragmentation.
Imagine a series of processes loading and finishing at different times:
Long-running processes leave small, empty gaps between them when shorter processes terminate.
Over time, memory becomes a checkerboard of allocated blocks and tiny free spaces.
If a new process requires 10 MB of memory, and you have three scattered free blocks of 4 MB each (total 12 MB free), the OS still cannot allocate memory to that process because the available 12 MB is split into noncontiguous chunks.
To fix this drawback, operating systems either have to perform an expensive overhead operation called compaction (moving all allocated blocks to one end of memory to create one large free block) or move to a modern paging/segmentation memory model.