External fragmentation is a phenomenon that occurs in computer memory allocation, where there is enough free space to accommodate a new program, but it is not contiguous. This means that the available memory is fragmented into small pieces, making it difficult to allocate the required space for a new program.
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| External Fragmentation in operating system |
External fragmentation is a common problem in operating systems that use dynamic memory allocation. When a program requests a certain amount of memory, the operating system looks for an unoccupied block of memory that is big enough to accommodate the request. However, if there is no contiguous block of memory that satisfies the request, the operating system has to either allocate multiple non-contiguous blocks or search for a way to consolidate the existing memory blocks.
External fragmentation can lead to several problems, such as slower program execution times, increased memory usage, and reduced system performance. To overcome external fragmentation, operating systems employ different techniques such as compaction and paging.
Compaction is a technique where the operating system relocates the programs in memory to consolidate the free memory blocks. This process requires a significant amount of computational overhead and can take up considerable amounts of time. Additionally, it may not be possible to compact the memory if the programs cannot be relocated.
Paging is a technique where the memory is divided into fixed-sized blocks called pages. The programs are then allocated to these pages, and the operating system maintains a table that maps the program's pages to their physical memory locations. This technique reduces external fragmentation as it allows the operating system to allocate non-contiguous memory blocks to a program.
To summarize, external fragmentation is a problem that occurs in computer memory allocation when free memory blocks are not contiguous. It can lead to slower program execution times, increased memory usage, and reduced system performance. Operating systems use different techniques such as compaction and paging to overcome this problem. By understanding external fragmentation and how to overcome it, developers can create programs that are more efficient and reliable.
In conclusion, external fragmentation is an essential concept in computer memory management, and its impact on system performance cannot be overstated. Developers and system administrators must take into account the different techniques available to overcome this issue and design their systems accordingly. By doing so, they can ensure that their programs run efficiently and smoothly, providing users with a seamless experience.