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With virtual memory, a contiguous range of virtual addresses can be mapped to several non-contiguous blocks of physical memory; this non-contiguous allocation is one of the benefits of paging. [8] [3] However, paged mapping causes another problem, internal fragmentation. This occurs when a program requests a block of memory that does not ...
This diagram represents five contiguous memory regions which each hold a pointer and a data block. The List Head points to the 2nd element, which points to the 5th, which points to the 3rd, thereby forming a linked list of available memory regions. A free list (or freelist) is a data structure used in a scheme for dynamic memory allocation.
Partitioned allocation divides primary memory into multiple memory partitions, usually contiguous areas of memory. Each partition might contain all the information for a specific job or task. Memory management consists of allocating a partition to a job when it starts and unallocating it when the job ends.
In contrast, a non-moving GC must visit each unreachable object and record that the memory it occupied is available. Similarly, new objects can be allocated very quickly. Since large contiguous regions of memory are usually made available by a moving GC, new objects can be allocated by simply incrementing a 'free memory' pointer.
Like stack allocation, regions facilitate allocation and deallocation of memory with low overhead; but they are more flexible, allowing objects to live longer than the stack frame in which they were allocated. In typical implementations, all objects in a region are allocated in a single contiguous range of memory addresses, similarly to how ...
Circular buffering makes a good implementation strategy for a queue that has fixed maximum size. Should a maximum size be adopted for a queue, then a circular buffer is a completely ideal implementation; all queue operations are constant time. However, expanding a circular buffer requires shifting memory, which is comparatively costly.
Normally, the (non-placement) new functions throw an exception, of type std::bad_alloc, if they encounter an error, such as exhaustion of all available memory. This was not how the functions were defined by Stroustrup's Annotated C++ Reference Manual , but was a change made by the standardization committee when the C++ language was standardized.
Stop-and-copy garbage collection in a Lisp architecture: [1] Memory is divided into working and free memory; new objects are allocated in the former. When it is full (depicted), garbage collection is performed: All data structures still in use are located by pointer tracing and copied into consecutive locations in free memory.