Which memory management scheme eliminates external fragmentation?

• A. Paging eliminates external fragmentation.
• B. Segmentation eliminates fragmentation.
• C. Paging causes external fragmentation.
• D. Bitmap allocation solves fragmentation.

Answer: (A)

External fragmentation happens when free memory is split into many small, noncontiguous holes, so a new process that needs a large block may not fit even though enough total free memory exists. Paging fixes this by splitting memory into fixed-size frames and the process address space into pages. Each page can be placed into any free frame, so there’s no requirement for a single contiguous block for a process. The system just uses as many free frames as needed, scattered across memory, which eliminates external fragmentation. The trade-off is that the last page of a process may not be completely full, leading to some internal fragmentation inside that final page, but external fragmentation is removed because free memory is a pool of uniform frames rather than a collection of variable-sized holes. Segmentation, with variable-sized segments, can suffer from external fragmentation because segments must be allocated contiguously. Bitmap allocation is a tracking method for free blocks and doesn’t by itself guarantee elimination of fragmentation; its impact depends on the underlying allocation unit. So paging is the scheme that eliminates external fragmentation.