Search results
Results From The WOW.Com Content Network
It will also change when already-running programs allocate or free private virtual memory; for example, with the VirtualAlloc and VirtualFree APIs. In the Task Manager utility under Windows XP and Windows Server 2003 , the graphical displays labeled as "PF usage" and "Page File Usage History," despite their labels, reflect not the pagefile ...
By reducing the I/O activity caused by paging requests, virtual memory compression can produce overall performance improvements. The degree of performance improvement depends on a variety of factors, including the availability of any compression co-processors, spare bandwidth on the CPU, speed of the I/O channel, speed of the physical memory, and the compressibility of the physical memory ...
Virtual memory allows processes to use more memory than is physically present in main memory. Operating systems supporting virtual memory assign processes a virtual address space and each process refers to addresses in its execution context by a so-called virtual address. To access data such as code or variables at that address, the process ...
In computer operating systems, memory paging (or swapping on some Unix-like systems) is a memory management scheme by which a computer stores and retrieves data from secondary storage [a] for use in main memory. [1] In this scheme, the operating system retrieves data from secondary storage in same-size blocks called pages.
It is the smallest unit of data for memory management in an operating system that uses virtual memory. Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system. [1] [2] [3]
A null pointer is usually represented as a pointer to address 0 in the address space; many operating systems set up the MMU to indicate that the page that contains that address is not in memory, and do not include that page in the virtual address space, so that attempts to read or write the memory referenced by a null pointer get an invalid ...
In some cases, a computer with virtual memory support where the majority of the loaded data resides on the hard disk may run out of physical memory but not virtual memory, thus causing excessive paging. This condition, known as thrashing, usually renders the computer unusable until some programs are closed or the machine is rebooted. Due to ...
Virtual memory combines active RAM and inactive memory on DASD [a] to form a large range of contiguous addresses.. In computing, virtual memory, or virtual storage, [b] is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" [3] which "creates the illusion to users of a very large (main) memory".