|
Explain the meaning of virtual memory. Virtual memory is an approach to make use of the secondary storage devices as an extension of the primary storage of the computer.
It is the process of increasing the apparent size of a computer's RAM by using a section of the hard disk storage as an extension of RAM.
Logically-assigned memory that may or may not exist physically. Through the use of paging and the swap area, more memory can be referenced and allocated than actually exists on the system, thus giving the appearance of a larger main memory than actually existsWhat is virtual memory?Most operating systems of desktop computers have a common part known as virtual memory. The use of virtual memory is so common because of its benefits provided to user at a lower cost.
Today most of the computers have RAM of capacity 64 or 128 MB to be used by the CPU resources. This amount of RAM is not sufficient to run all applications that are used by most users in their expected way and all at once. For example, an e-mail program, a web browser and a word processor is loaded into RAM simultaneously; the 64 MB space is not enough to store all these programs. In the absence of virtual memory, a message “Sorry, you cannot load any more applications. Please close an application to load a new one.” would be displayed. With the use of virtual memory, a computer can look for empty areas of RAM which is not being used currently and copies them on to the hard disk device. This process frees up RAM to load new applications. As it is done automatically, the user do not even know that it is happening, and the user feels like RAM has unlimited space even though the RAM capacity is 32 MB. The fact that hard disk space is much cheaper than RAM chips allows virtual memory also as a nice economic benefit.
The RAM images are stored in the hard disk and known as page file. It contains the pages of RAM, and the data moves back and forth between the pages file and RAM by the operating system. The page files on a machine with Windows operating system have a .SWP extension.
The read/write speed of a hard disk drive is slower than RAM. The hard disk’s technology is not upgraded to access small pieces of data at a given point of time. If the reliance of a system is too heavy on virtual memory, a significant performance drop would be noticed. The key for this is to have sufficient amount of RAM to handle all aspects that tend to work simultaneously. The feel of slowness of virtual memory is a slight pause at the time of changing tasks. Virtual memory works beautifully with sufficient RAM availability. If not, the operating system must swap information back and forth between RAM and the hard disk constantly. This process is called ‘trashing’, and also causes the feel to the user that the computer system is incredibly slow.Explain the meaning of virtual memory.Virtual Memory is a feature of an operating system. Virtual memory enables memory address space usage by a process which is independent of other processes running at the same time and uses memory space which is larger than RAM. It relegates temporarily some content that is available in RAM to disk.
|
