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Encyclopedia > Memory allocation
It has been suggested that this article or section be merged with Dynamic memory allocation. (Discuss)

Memory allocation, in computer science, is the act of setting aside memory for a program to use for future usage. This is done typically for storing variables, code or data. Memory allocation is a widely discussed topic in the field of operating systems, as computers have limited memory, and many programs need memory to run. To find out more, you can look up on the various memory allocation algorithms and techniques that can be used. Wikipedia does not have an article with this exact name. ... It has been suggested that this article or section be merged with Memory allocation. ... Wikibooks Wikiversity has more about this subject: School of Computer Science Open Directory Project: Computer Science Downloadable Science and Computer Science books Collection of Computer Science Bibliographies Belief that title science in computer science is inappropriate Categories: Computer science ... In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

Contents


Allocation techniques

Alternate meanings: See paging (telecommunications). ... The buddy memory allocation technique is a memory allocation technique that divides memory into partitions to try and satisfy a memory request as suitably as possible. ... It has been suggested that this article or section be merged with Memory allocation. ...

Fixed-size-blocks allocation

One solution is to have a LIFO linked list of fixed size blocks of memory. This works astonishingly well for simple embedded systems. In a stack, the topmost item, which is added last, is taken out first. ... In computer science, a linked list is one of the fundamental data structures used in computer programming. ... An embedded system is a special-purpose computer system, which is completely encapsulated by the device it controls. ...


Buddy blocks

Another solution is to have a binary buddy block allocator. In this system, memory is allocated from a large block of memory that is a power of two in size. If the block is more than twice as large as desired, it is broken in two. One of the halves is selected, and the process repeats (checking the size again and splitting if needed) until the block is just large enough. The buddy memory allocation technique is a memory allocation technique that divides memory into partitions to try and satisfy a memory request as suitably as possible. ... In mathematics, a power of two is any of the nonnegative integer powers of the number two; in other words, two times itself a certain number of times. ...


All the buddies of a particular size are kept in a sorted linked list or tree. When a block is freed, it is compared to its buddy. If they are both free, they are combined and placed in the next-largest size buddy-block list. (When a block is allocated, the allocator will start with the smallest sufficiently large block avoiding needlessly breaking blocks) In computer science, a tree is a widely-used computer data structure that emulates a tree structure with a set of linked nodes. ...


Note that buddy block allocators are not unique to real-time operating systems, they are also used in conventional operating systems (such as the Linux kernel). A Real Time Operating System (RTOS) is an operating system that has been developed for real-time applications. ... Unix systems filiation. ...


See also


  Results from FactBites:
 
Buddy memory allocation - Wikipedia, the free encyclopedia (806 words)
Compared to the memory allocation techniques (such as paging) that modern operating systems such as Microsoft Windows and Linux use, the buddy memory allocation is relatively easy to implement, and does not have the hardware requirement of a memory management unit (MMU).
Typically the buddy memory allocation system is implemented with the use of a binary tree to represent used or unused split memory blocks.
Because the buddy algorithm is used for kernel memory allocation, it is essential to lower the amount of internal fragmentation.
Dynamic memory allocation - Wikipedia, the free encyclopedia (530 words)
A dynamically allocated object remains allocated until it is deallocated explicitly, either by the programmer or by a garbage collector; this is notably different from automatic and static memory allocation.
In this system, memory is allocated from a large block of memory that is a power of two in size.
In contrast, the call stack memory is usually of limited size and the lifetime of the allocation depends on the duration of the corresponding functions.
  More results at FactBites »

 
 

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