Essay on Computer Memory : Virtual Memory

Essay on Computer Memory : Virtual Memory

Length: 2610 words (7.5 double-spaced pages)

Rating: Strong Essays

Open Document

Essay Preview

UNIX has a technique called Virtual Memory to accommodate for the shortage of memory space. Virtual memory increases the available memory the computer has by enlarging the "address space," or places in memory where data can be stored. This paper describes concepts like swapping, demand paging, page fault, page replacement algorithm, thrashing, some virtual memory allocation algorithms and the Memory Management Unit (MMU).
Each program running on the machine is called a process and each process has its own address space that the process uses to store its data and code segments. Sometimes there is not enough memory to hold the entirety of large programs or when too many programs are running together on the machine. As a get around, UNIX uses a technique called Virtual Memory. Virtual memory is the use of space on the hard disk to simulate additional RAM [1]. In order to free up space in memory, the UNIX operating system transfers data that is not immediately needed from memory to the HDD; when that data is needed again, it is copied back into memory. That is, when all of the RAM is busy performing some task, a computer with virtual memory enabled will ‘swap’ data to the HDD and back to memory as needed, thus, in effect, increasing the total system memory. The operating system and hardware map the virtual address to the physical address when information needs to be stored or retrieved by a program
The physical main memory behaves like a set of windows or caches on a much larger "virtual" memory space, most of which at any given time is actually stored on disk in a special zone called the swap area. Virtual memory permits software to run in a memory space (i.e., a logical memory) whose size is greater than...

... middle of paper ... memory for other uses thus allowing many more programs to run simultaneously.
• Virtual memory allows non-contiguous physical memory blocks to be used as contiguous virtual memory.
When a virtual address needs to be translated into a physical address, the TLB is searched first. If a match is found (a TLB hit), the physical address is returned and memory access can continue. However, if there is no match (called a TLB miss), the handler will typically look up the address mapping in the page table to see whether a mapping exists (a page walk). If one exists, it is written back to the TLB (this must be done, as the hardware accesses memory through the TLB in a virtual memory system), and the faulting instruction is restarted (this may happen in parallel as well). This subsequent translation will find a TLB hit, and the memory access will continue.

Need Writing Help?

Get feedback on grammar, clarity, concision and logic instantly.

Check your paper »

Essay about Real Memory

- In computers, memory is referred to as a mechanism with the ability to store data and information. Storing data within a computer can be done in a variety of ways across multiple device platforms. Desired data information can be stored permanently or even temporarily. Unquestioned in computing, memory management is the fundamental act of properly distributing the appropriate and most fitting portions of memory among programs. This is all possible due to a unit known as real memory. Real memory deals with the actual hardware of a computer known as memory chips or commonly known as ram....   [tags: virtual memory, paging, segmentation]

Strong Essays
2131 words (6.1 pages)

Exercise : What Is Virtual Memory? Essay

- Julissa Tejeda CSCI 12700 Assignment 2 Exercise 0: What is virtual memory. Virtual memory is the illusion of memory space in a computer 's main memory. The memory manager records the bit patterns of data that needs to be stored on a magnetic disk. This data is divided into pages, which are uniform sized units of data. The memory manager then shuffles these pages back and forth between main memory and main storage. The manager shuffles the pages in a way that places the pages that are needed for the program to run in main memory....   [tags: Operating system, Graphical user interface, Linux]

Strong Essays
707 words (2 pages)

A Stroke’s Effect on Memory Essay example

- Stroke is a medical condition most people are familiar with, but most people are unaware of its effect on memory functions. There have been several studies conducted that study of effects of stroke on different memory systems, how to properly assess memory damage in stroke patients as well as how to improve memory after stroke. A major theme from the course that relates to stroke and memory is the theme of metamemory and its components such as prospective memory. Personally, I believe that these studies offer hope to stroke victims and their families because memory damage can evaluated and therefore a method of treatment can be developed....   [tags: health, memory functions]

Strong Essays
1982 words (5.7 pages)

Computer Memory Essay

- One of the fundamental and core functions of computers is data storage. The computer has components that retain digital data and record media used for computation. The data stored is in form of bits and bytes. Fast but temporary storage in the computer are often referred to as memory while storage can refer to the storage devices that are not directly accessible, by the Central Processing Unit. Computers use several memory types organized in a storage hierarchy, in the Central Processing Unit....   [tags: Data Storage, Types]

Strong Essays
852 words (2.4 pages)

Virtual Learning Environment in Education Essay

- Title: Virtual Learning Environment in Education Motivation behind the study. Education is the one of important thing where people will gain their knowledge. Education consist of many level of ages that and the delivery method in education is varies. One of the ways that educations are transfer through Virtual Learning Environment (VLE). VLE is a system generated computer that display in 3Dimension (3D). Virtual reality (VR), the three-dimensional multisensory, immersive, and interactive digital environment, has triggered public imagination as the technology that will dominate the way our work, education, and leisure are delivered in the future....   [tags: motivation, virtual environment, knowledge]

Strong Essays
1301 words (3.7 pages)

A High-Performance Memory Allocator for Computer Systems Essay example

- In today’s CMOS VLSI technology makes it possible to combine a very powerful processor onto a single chip. NUMA (Non uniform Memory Access time) multiprocessor designs were of increasing importance as they were involved in supporting shared memory on a huge scale. For such systems, the placement and movement of code as well as data are crucial to performance. This needs to deal with data placement problems and this has been called the “NUMA Problem.” Presenting the programmer with an explicit NUMA memory model resulted in a significant kind of extra programming burden....   [tags: numa, memory model, programming, ip]

Strong Essays
1098 words (3.1 pages)

Exploring Virtual Memory Essays

- Exploring Virtual Memory Virtual memory is an old concept. Before computers utilized cache, they used virtual memory. Initially, virtual memory was introduced not only to extend primary memory, but also to make such an extension as easy as possible for programmers to use. Memory management is a complex interrelationship between processor hardware and operating system software. For virtual memory to work, a system needs to employ some sort of paging or segmentation scheme, or a combination of the two....   [tags: paging, segmentation, replacement]

Strong Essays
1713 words (4.9 pages)

An Effective Memory Optimization for Virtual Machine-Based Systems Essay

- An Effective Memory Optimization for Virtual Machine-Based Systems Overview: A new technique called Batmem is introduced in this paper to increase the system performance. This techniques is applied to both high end and low end systems by which we can increase the performance of virtual atmosphere and warns user frequently about malicious deeds that happens in system. Summary: VMM's(Virtual Machine Monitor) require a powerful memory offering component between VMM's and their host, for example, improving regular paging and memory that is mapped for virtual I/O gadgets....   [tags: information technology, batmem]

Strong Essays
2035 words (5.8 pages)

How To Backup Virtual Servers Essay

- As server virtualisation assumes a greater role in the enterprise, administrators face a proliferation of virtual machines residing on the same physical server. Each virtual machine uses a portion of the physical machine's processing, memory and I/O resources. Ideally, server virtualisation provides a means of increasing hardware utilisation. But as more "logical" servers are consolidated into fewer "physical" computer systems, it's important to protect each virtual machine's data against failure or loss....   [tags: Process Server Computer Technology]

Free Essays
1982 words (5.7 pages)

Memory Management Essay

- Memory Management A computer capable of running a multi-tasking system may have to deal with widely varying demands for memory. At some times, no users may be logged on and the only tasks running are the kernel and possibly a backup process. At other times, ten or more users may all be carrying out complex operations which demand lots of memory. Microsoft Windows versions 3.x provided a protected mode graphical operating environment that ran existing MS-DOS applications and allowed Windows applications to break the 640K barrier....   [tags: Essays Papers]

Strong Essays
903 words (2.6 pages)