Explain the difference between internal and external fragmentation.
The Correct Answer and Explanation is :
Internal Fragmentation vs. External Fragmentation
Internal Fragmentation occurs when memory is allocated in fixed-size blocks, and the allocated memory is larger than what is actually needed by the process. This results in unused space within the allocated memory block, which cannot be used by other processes. This type of fragmentation happens within the allocated space, making it “internal.”
External Fragmentation, on the other hand, refers to the situation where free memory is scattered in small blocks across the system, and although there may be enough total free memory to satisfy a request, it is not contiguous. The free space is split into small, non-adjacent regions, making it impossible to allocate memory efficiently to a process that needs a large contiguous block.
Explanation:
- Internal Fragmentation:
This type of fragmentation happens when a memory block is allocated to a process, but the process doesn’t fully use the allocated block. The leftover unused space within the allocated block is wasted. For example, if the operating system allocates a 4 KB block to a process that only needs 2 KB, the remaining 2 KB in that block becomes unusable by other processes, leading to internal fragmentation. - External Fragmentation:
In this case, memory is allocated in varying sizes and freed in between different allocations. As processes are loaded and unloaded, free memory spaces are scattered throughout the system. If these free spaces are too small and fragmented, it may become impossible to allocate a larger block of memory to a process even though there is enough total free memory. For example, if there are free blocks of 2 KB, 3 KB, and 5 KB, but a process requires a 6 KB block, the system cannot allocate the required memory despite having 10 KB of free space in total.
Both types of fragmentation can lead to inefficient memory usage, but internal fragmentation is typically easier to manage because the unused space is contained within allocated blocks, whereas external fragmentation can require more complex memory management strategies such as defragmentation.