What is Virtual Memory?
A. Virtual Memory makes up for the lack of RAM in computers by using space on the hard disk as memory, Virtual Memory. When the actual RAM fills up then virtual memory is created on the hard disk. When physical memory runs out, the Virtual Memory Manager chooses sections of memory that have not been recently used and are of low priority and writes them to the swap file. This process is hidden from applications, and applications views both virtual and actual memory as the same. Each application that runs under Windows NT is given its own virtual address space of 4GB (2GB for the application, 2GB for the operating system). The problem with Virtual Memory is that as it writes and reads to the hard disk, this is much slower than actual RAM. This is why if an NT system does not have enough memory it will run very slowly.
Virtual memory is found among all computer operating systems and it provides some very practical benefits to PC users. All computer systems have their own RAM (Physical Random Access Memory) which commonly ranges from 64 to 256 megabytes. When virtual memory is being used, the system allows the users to carry on working without worrying about the availability of data storage or memory saturation. It is often addressed as logical memory and allows users to access a larger volume of memory, allowing them to use more applications simultaneously. With virtual memory, the system is able to search for applications on the RAM that aren’t being used and copies the same on to the hard disk. As a result, more space is freed up on RAM and new applications can be loaded that need to be immediately used. The entire process is done automatically and the user doesn’t need to click on anything. It functions by dividing the address space of the application programs into many smaller pages. These smalle
Virtual memory is a common part of most operating systems on desktop computers. It has become so common because it provides a big benefit for users at a very low cost. Most computers today have something like 64 or 128 megabytes of RAM (random-access memory) available for use by the CPU (central processing unit). Often, that amount of RAM is not enough to run all of the programs that most users expect to run at once. For example, if you load the Windows operating system, an e-mail program, a Web browser and word processor into RAM simultaneously, 64 megabytes is not enough to hold it all. If there were no such thing as virtual memory, your computer would have to say, “Sorry, you cannot load any more applications. 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. This frees up space in RAM to load the new application. Because it does this automatically, you don’t
Linux supports virtual memory, that is, using a disk as an extension of RAM so that the effective size of usable memory grows correspondingly. The kernel will write the contents of a currently unused block of memory to the hard disk so that the memory can be used for another purpose. When the original contents are needed again, they are read back into memory. This is all made completely transparent to the user; programs running under Linux only see the larger amount of memory available and don’t notice that parts of them reside on the disk from time to time. Of course, reading and writing the hard disk is slower (on the order of a thousand times slower) than using real memory, so the programs don’t run as fast. The part of the hard disk that is used as virtual memory is called the swap space. Linux can use either a normal file in the filesystem or a separate partition for swap space. A swap partition is faster, but it is easier to change the size of a swap file (there’s no need to repa
Computer users place great demands on their computers and computing devices today more than ever before. The size and complexity of modern sophisticated computer applications the vast amounts of information that is being stored, shared, and utilized daily requires that large amounts of computer memory remain available so the computer can access and present data in an effective manner.
