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In computer storage, fragmentation is a phenomenon in which storage space, such as computer memory or a hard drive, is used inefficiently, reducing capacity or performance and often both. The exact consequences of fragmentation depend on the specific system of storage allocation in use and the particular form of fragmentation.
Initially, the system marks each slab as "empty". When the process calls for a new kernel object, the system tries to find a free location for that object on a partial slab in a cache for that type of object. If no such location exists, the system allocates a new slab from contiguous virtual pages and assigns it to a cache.
An example of the fragmentation of a protocol data unit in a given layer into smaller fragments. IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces (fragments), so that the resulting pieces can pass through a link with a smaller maximum transmission unit (MTU) than the original packet size.
There is a utility, iDefrag, by Coriolis Systems available since OS X 10.3. On traditional Mac OS defragmentation can be done by Norton SpeedDisk and TechTool Pro. WAFL in NetApp's ONTAP 7.2 operating system has a command called reallocate that is designed to defragment large files. XFS provides an online defragmentation utility called xfs_fsr.
In comparison to other simpler techniques such as dynamic allocation, the buddy memory system has little external fragmentation, and allows for compaction of memory with little overhead. The buddy method of freeing memory is fast, with the maximal number of compactions required equal to O(highest order) = O(log 2 (total memory size)).
File system fragmentation is more problematic with consumer-grade hard disk drives because of the increasing disparity between sequential access speed and rotational latency (and to a lesser extent seek time) on which file systems are usually placed. [8] Thus, fragmentation is an important problem in file system research and design.
Memory management (also dynamic memory management, dynamic storage allocation, or dynamic memory allocation) is a form of resource management applied to computer memory.The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when no longer needed.
The specific operating system and executable format determine how the dynamic linker functions and how it is implemented. Linking is often referred to as a process that is performed when the executable is compiled , while a dynamic linker is a special part of an operating system that loads external shared libraries into a running process and ...