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| | Virtual memory - Wikipedia, the free encyclopedia |
 | | Virtual memory or virtual memory addressing is a memory management technique, used by multitasking computer operating systems wherein non-contiguous memory is presented to a software application (aka process) as contiguous memory. | | | Virtual memory was developed in approximately 1959 - 1962, at the University of Manchester for the Atlas Computer, completed in 1962. | | | Note that virtual memory is not a requirement for precompilation of software, even if the software is to be executed on a multiprogramming system. |
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http://en.wikipedia.org/wiki/Virtual_memory
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| | Category:Virtual memory - Wikipedia, the free encyclopedia |
| | Virtual memory is a computer design feature that permits software to use more main memory (the memory which the CPU can read and write to directly) than the computer actually physically possesses. |
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http://en.wikipedia.org/wiki/Category:Virtual_memory
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| | Virtual Memory Definition |
| | Virtual memory was incorporated into the UNIX kernel (i.e., the core of the operating system) in the 1970s as part of the Berkeley Extensions, which were developed at the University of California at Berkeley (UCB). | | | Virtual memory is so important that its acronym, i.e., vm, was incorporated into the name of the Linux kernel as it is used on most systems, i.e., vmlinux for the non-compressed version and vmlinuz for the compressed, bootable (i.e., runnable) version. | | | Virtual memory permits software to run in a memory space (i.e., a logical memory) whose size is greater than the computer's RAM. |
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http://www.bellevuelinux.org/virtual.html
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| | Howstuffworks "What is "virtual memory"?" |
| | Virtual memory is a common part of most operating systems on desktop computers. | | | Please close an application to load a new one." With virtual memory, the computer can look for areas of RAM that have not been used recently and copy them onto the hard disk. | | | Most computers today have something like 64 or 128 megabytes of RAM (random-access memory) available for use by the CPU (central processing unit). |
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http://computer.howstuffworks.com/question684.htm
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| | Managing Virtual Memory in Win32 (Memory Technical Articles) |
| | Because the addresses themselves are represented independent of the memory that may or may not be committed to them, querying them is simply a matter of accessing the data structure that maintains their state. | | | The virtual memory functions are considered low-level functions, meaning they are relatively fast but they lack many high-level features. | | | The maximum amount of memory that can be committed is based solely on the maximum range of contiguous free or reserved addresses (but not a combination of both), regardless of the amount of physical memory available to the system. |
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http://msdn.microsoft.com/library/techart/msdn_virtmm.htm
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| | redhat.com Red Hat Magazine - Understanding Virtual Memory |
| | Virtual Memory (VM) allows an operating system to perform many of its advanced functions, such as process isolation, file caching, and swapping. | | | As such, it is imperative that an administrator understand the functions and tunable parameters of an operating system's Virtual Memory Manager so that optimal performance for a given workload may be achieved. | | | A page fault is encountered every time a virtual memory address is accessed for which there is not yet a corresponding physical page assigned or for which the corresponding physical page has been swapped to disk. |
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http://www.redhat.com/magazine/001nov04/features/vm
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| | Define virtual memory - a Whatis.com definition |
| | Virtual (or logical) memory is a concept that, when implemented by a computer and its operating system, allows programmers to use a very large range of memory or storage addresses for stored data. | | | In addition to managing the mapping of virtual storage addresses to real storage addresses, a computer implementing virtual memory or storage also manages storage swapping between active storage (RAM) and hard disk or other high volume storage devices. | | | The computing system maps the programmer's virtual addresses to real hardware storage addresses. |
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http://searchstorage.techtarget.com/sDefinition/0,,sid5_gci213300,00.html
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| | CIS 307: Virtual Memory |
| | A Virtual Memory system is a system where the addresses used in executing images, Virtual Addresses, are different from the addresses, Physical Addresses, used at the hardware level, on the bus between processor and main memory. | | | By calibrating carefully the amount of main memory made available to a process (and the size of cache memory available on the processor) it is possible to achieve virtual memories that have access times that are better, on average, than physical memory and size comparable to that of secondary storage. | | | The beauty of virtual memory is that it is like a game that can be played more than once, not only between main memory and secondary storage, but also between cache memory and main memory. |
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http://www.cis.temple.edu/~ingargio/cis307/readings/virtual.html
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| | CS322: Virtual Memory |
| | We saw that the earliest computer systems operated on a memory model that required that all of the memory required by a given process be allocated to it in a single, contiguous region of physical memory. | | | In a virtual memory system, we no longer require that all of the pages belonging to a process be physically resident in memory at one time. | | | We have seen that, under a virtual memory system, it is possible for the logical memory allocated to any one process to exceed the amount of physical memory available. |
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http://www.cs.gordon.edu/courses/cs322/lectures/virtual_memory.html
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| | Virtual Memory |
| | Personal computers in the 1980s did not use virtual memory. | | | Before computers had cache, they had virtual memory. | | | In fact, many good ideas that were in common use in the UNIX operating systems didn't appear until the mid 1990s in personal computer operating systems (pre-emptive multitasking and virtual memory). |
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http://www.cs.umd.edu/class/spring2003/cmsc311/Notes/Memory/virtual.html
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| | Memory Management 2: virtual memory |
| | This is similar to the virtual memory allocator I just described, except that we already have a record of the executable’s sections in the header. | | | One useful feature is the ability of the virtual memory manager to swap pages to and from disk. | | | Why not map the file into memory as it appears on disk, headers and all. |
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http://www.openbg.net/sto/os/xml/memory2.html
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| | OSD: Virtual memory |
| | The task virtual memory is private to each task; the identity-mapped and kernel virtual memory are shared among all tasks. | | | Since memory fragmentation is not an issue for these, they may be stored in identity-mapped memory or kernel virtual memory, whichever is more convenient. | | | This means the virtual addresses generated by a program are different from the physical addresses that go onto the address bus; to the memory chips. |
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http://my.execpc.com/CE/AC/geezer/osd/mem
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| | virtual memory |
| | Similarly, a multitasking system might load the whole program and its data into physical memory when it is to be executed and copy it all out to disk when its timeslice expired. | | | Some application programs implement virtual memory wholly in software, by translating every virtual memory access into a file access, but efficient virtual memory requires hardware and operating system support. | | | The offset is left unchanged and the memory management unit (MMU) maps the virtual page number to a physical page number. |
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http://burks.brighton.ac.uk/burks/foldoc/72/124.htm
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| | TweakHound - Understanding Virtual Memory |
| | Memory reclamation in XP even goes further than this to make the process as seamless as possible, using more algorithms than most can appreciate. | | | Once information is brought into memory (it must be paged in), the operating system will choose for that process the memory reclamation strategy. | | | “When a process allocates a piece of private virtual memory (memory not backed by an image or data file on disk, which is considered sharable memory), the system charges the allocation against the commit limit. |
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http://www.tweakhound.com/xp/virtualmemory.htm
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| | What is virtual memory? - A Word Definition From the Webopedia Computer Dictionary |
| | A program using all of virtual memory, therefore, would not be able to fit in main memory all at once. | | | For example, virtual memory might contain twice as many addresses as main memory. | | | The copying of virtual pages from disk to main memory is known as paging or swapping. |
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http://www.webopedia.com/TERM/V/virtual_memory.html
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| | CS 210 - Computer Systems - Unit 10 |
| | However, when the computer is running multiple programs that fit in memory, but all programs are run by the same user, the use of VM is optional. | | | The idea behind virtual memory is that addresses generated by the CPU are inspected and translated before they are allowed to affect memory. | | | Locality of reference means that the memory references made by a program tend to be close to each other from reference to reference. |
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http://cs-www.bu.edu/faculty/djy/cs210/unit10.html
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| | MemoKit - Computer memory manager and optimizer, virtual memory and cache optimizer |
| | Memory is most crucial in computer speed and stability. | | | Virtual Memory and Hard Disk Cache Optimizer changes and tracks so-called Virtual Cache parameters of the hard disk, which improves hard disk performance. | | | MemoKit - Computer memory manager and optimizer, virtual memory and cache optimizer |
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http://www.memoryoptimizer.com
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| | Virtual memory |
| | Virtual memory is a method of using the computer hard disk drive to provide extra memory for the computer. | | | Segments of memory are stored on the hard disk drive known as pages. | | | Also see: Memory definitions, Roll in, Swap file |
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http://www.computerhope.com/jargon/v/virtmemo.htm
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| | virtual memory |
| | Virtual memory, Peter, is what the operating system uses when it runs out of real internal memory (RAM). | | | As Patty said, the amount of virtual memory you need is dependent on what you are doing. | | | If you rarely see this warning then you may allow Windows to handle memory and live with that warning since XP can handle virtual memory pretty well. |
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http://www.computerhaven.info/forum/fb.aspx?m=7849
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| | Virtual Memory |
| | Whenever you're using a lot of virtual memory, you're slowing your computer down (way the heck down). | | | I recommend 64 - 128 meg, depending on how many programs you run simultaneously. | | | Why bother to add extra RAM to my computer if it can use hard drive space instead? |
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http://www.worldstart.com/tips/computer-terms/termvirtualmemory.htm
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| | NetBSD Documentation: UVM, the new Virtual Memory system |
| | In UVM, your total virtual memory is equal to the size of your physical RAM (minus kernel overhead) plus the size of each swap partition. | | | UVM is a complete rewrite of the NetBSD virtual memory system, and has proven to be a much better performer than the Mach VM system. | | | In other words, physical memory doesn't have to be backed by a paging device. |
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http://www.netbsd.org/Documentation/kernel/uvm.html
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| | Virtual Memory |
| | For better performance, the file system is often bypassed and virtual memory is stored in a special area of the disk called the swap space | | | An interrupt (memory fault) is generated when the memory reference is on a piece not present in main memory | | | By contrast, physical memory is the memory referenced by a physical address |
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http://www.shsu.edu/~csc_tjm/fall2000/cs431/Chap08TJM.html
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| | Virtual Memory - Cyber Tech Help Support Forums |
| | Hi all, I was wondering how I would go about increasing the amount of virtual memory on my machine? | | | Everytime I play a certain one of my games an icon pops up in the system tray that says I am very low on virtual memory. | | | Right-click My Computer, choose Properties, Advanced tab, Settings button in Performance section, Advanced tab, Change button in Virtual memory section. |
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http://www.cybertechhelp.com/forums/showthread.php?t=13960
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| | Encyclopedia4U - Virtual Memory System - Encyclopedia Article |
| | The OpenVMS (Open Virtual Memory System) operating system (OS), also known as VMS, is a multiuser, multiprocessing OS that was designed by Digital (now owned by Hewlett-Packard) in conjunction with their 32-bit VAX processor for use in time sharing, batch processing, and transaction processing. | | | OpenVMS also runs on the 64-bit Alpha processor, and an upcoming port has been demonstrated on the Itanium processor. | | | Encyclopedia4U - Virtual Memory System - Encyclopedia Article |
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http://www.encyclopedia4u.com/v/virtual-memory-system.html
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