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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 ...
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 ...
Later compilers did not attempt to do this, but used real pointers, often implementing their own memory allocation schemes to work around the Mac OS memory model. While the Mac OS memory model, with all its inherent problems, remained this way right through to Mac OS 9, due to severe application compatibility constraints, the increasing ...
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.
The slab allocation algorithm defines the following terms: Cache: cache represents a small amount of very fast memory. A cache is a storage for a specific type of object, such as semaphores, process descriptors, file objects, etc. Slab: slab represents a contiguous piece of memory, usually made of several virtually contiguous pages. The slab is ...
This gave rise to the use of heap storage and some memory management routines. To ease the overhead, TPF memory was broken into frames— 4 KB in size (1 MB with z/TPF). If an application needs a certain number of bytes, the number of contiguous frames required to fill that need are granted.