Memory Fragmentation Ratio

• Memory allocation in non-contiguous blocks.
• There are two fragmentations:
  • External
  • Internal
• Virtual memory creates a mapping between physical memory blocks.
• Internal and external fragmentation are two issues that can occur in systems that allocate memory to processes. Understanding the differences between them is crucial for efficient memory management.

Internal Fragmentation

Internal fragmentation occurs when fixed-sized memory blocks are allocated to processes. If the memory allocated to a process is larger than what the process actually needs, the unused portion of the memory block is wasted. This happens because the memory is divided into fixed-sized partitions, and a process may not use the entire partition. The wasted space within these allocated blocks is what constitutes internal fragmentation^[1][2][3].

External Fragmentation

External fragmentation, on the other hand, happens when memory is allocated in variable-sized blocks. As processes are loaded and unloaded from memory, the free memory space becomes fragmented into small, non-contiguous blocks. This can prevent new processes from being allocated memory, even if the total free memory is sufficient, because there isn't a single contiguous block large enough to accommodate them. External fragmentation is a result of dynamic memory allocation methods that leave unusable gaps between allocated memory blocks^[4][5][6].

Key Differences

• Allocation Method: Internal fragmentation is associated with fixed-sized memory blocks, while external fragmentation is associated with variable-sized memory blocks^[1:1][2:1].
• Occurrence: Internal fragmentation occurs when a process is allocated more memory than it needs within a fixed partition. External fragmentation occurs when there is enough total memory, but it is not contiguous due to previous allocations and deallocations^[4:1][2:2].
• Solution: The best-fit allocation strategy can help reduce internal fragmentation by minimizing the wasted space within partitions. Solutions to external fragmentation include compaction (which consolidates free memory into a contiguous block), paging, and segmentation, which allow processes to be allocated non-contiguous memory blocks^[7][2:3][8].

Managing Fragmentation

To manage internal fragmentation, one can use dynamic memory allocation strategies that minimize wasted space. For external fragmentation, techniques like compaction, paging, and segmentation can be employed to better utilize the available memory^[3:1][9].

In summary, internal fragmentation is about wasted space within allocated memory blocks due to fixed-size allocation, and external fragmentation is about the inability to use free memory effectively due to its non-contiguous distribution. Both types of fragmentation can lead to inefficient use of memory and can affect system performance.

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