Virtual Memory: Everything You Need to Know

What is Virtual Memory?

Virtual memory is primarily a storage allocation technique in a computer's Operating System to emulate the computer's RAM. Virtual storage optimizes memory management by transferring data between Random Access Memory (RAM) and hard disk, using hardware and software to compensate for the computer's physical memory shortage. Hence, virtual memory gives the user an illusion of a big main memory. 

Most computers today have 8 gigabytes (GB) of RAM, but sometimes, more than the memory is needed to run applications smoothly and effectively. Therefore, virtual memory is used for effectiveness, multitasking, and smooth running of applications. However, relying less on the virtual memory is recommended as it is slower than the RAM and can cause inconsistencies in the system. 

How Does Virtual Memory Work?

Hardware and software are both needed for virtual memory to function. RAM stores program data in a physical address when an application is used. Memory addresses are automatically translated by a memory management unit (MMU), which maps the address to RAM.

If RAM space is urgently required, data is swapped from RAM to virtual storage or memory. The computer's memory manager is responsible for keeping track of the change or shift between physical and virtual memory. 

The operating system partitions memory with several addresses into pagefiles or swaps files while moving virtual memory to physical memory. Every page is kept on a disc, which is then copied to the main memory by the operating system, which converts virtual addresses into actual addresses when the page is needed.

Therefore, computers with more RAM are considered to work more effectively and safely, as swapping and extensive use of virtual memory causes an apparent reduction in the performance of computers. 

Types of Virtual Memory

A computer's MMU is responsible for managing the operations of virtual memory. The MMU hardware is typically built into the computers' central processing unit (CPU). The CPU also creates the virtual address space. Virtual memory is typically segmented or paged. Each type of virtual memory has its own function and is preferred by different users. 

Paging

One of the most popular methods of virtual memory management is memory paging. It stores the least used process pages in the secondary memory. The data offloaded by the computer's RAM is stored in a swap file, a specific location on the hard drive that the computer uses for this purpose. To ensure it never runs out of real memory, the computer moves unnecessary files to its hard drive, freeing up RAM for other memory-intensive operations.

Segmenting

In segmenting, memory is divided into segments of varying lengths. Moreover, the unused segments are moved from the computer's memory space to its hard drive. Segment tables keep track of the storing of sections in virtual memory and physical addresses.

Segmenting divides memory into sections of various lengths, while paging does it in equal sections. Moreover, although Segmentation is slower than paging, it provides more access to the user in determining the length of the section. Therefore, different virtual memory in OS types depends on the user's needs. 

Advantages of Virtual Memory

Virtual memory in OS has undeniably made many users' lives easier and has many advantages. 

• Preventing the requirement to buy extra RAM
• Enabling the execution of programs on machines larger than their physical memory
• Executing several programs concurrently or multitasking
• Increasing the rate at which our computer utilizes its physical memory
• Permitting the deployment of a multiprogramming environment without any restrictions
• Programs that can estimate the physical addresses of other programs increase data security
• Making it easier to debug simultaneous execution of many applications

Moreover, administrators can utilize virtual memory management strategies in a virtualized computing environment to provide extra memory to a virtual machine (VM) that has exhausted its resources. VM performance and administration flexibility can both be enhanced by such virtualization management strategies.

Disadvantages of Virtual Memory

Although we cannot deny the innumerable benefits of virtual memory, a few drawbacks might be a dealbreaker for many users.

• As physical memory is faster and easier to access, computers prefer to use it over virtual memory.
• Virtually stored apps may take longer to load because computers must transition between virtual and physical memory.
• Thrashing is a phenomenon where a computer with little RAM always alternates between virtual and physical memory. Performance lags may result from the computer becoming slower as a result.
• A computer's available memory is usually decreased if it has little secondary storage.
• Additional hardware support makes transferring data between a computer's virtual and real memory easier.
• Large apps take up virtual storage space when opened and stored, which is normally used by computers to store long-term data.
• It lowers the overall performance and stability of the system.

Conclusion

Indubitably, the development of virtual memory in OS has made the lives of computer users easier with increased system stability and memory capacity. Although virtual storage may result in performance lag and slowing, it tends to be inexpensive compared to RAM.

University of Manchester in Manchester, England, is first credited for the attempt to develop virtual memory storage. However, virtual storage was not incorporated in early PCs as developers needed to consider running out of memory a problem in those machines. Intel incorporated virtual memory in its protected mode in 1982 and opened a new realm of development and ease to the world of computers. 

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FAQ's

1. What is virtual memory and its example?

Virtual memory is primarily a storage allocation technique in a computer's OS to emulate the computer's RAM and provide the illusion of a bigger main memory. 

For example, a student takes advantage of the virtual memory mechanism on their computer to execute several programs at once. The user attempts to open a content management system, word processing program, and shift scheduling program in addition to their email in a browser window.

2. Is virtual memory a type of RAM?

No, the physical memory that houses a computer's programs, documents, and operations is called random access memory, or RAM. When a computer's RAM runs empty, files from our hard drive can be retrieved from virtual memory.

3. Which memory is called virtual memory?

The memory management technique in  OS optimizes memory management by transferring data between Random Access Memory (RAM) and hard disk, using hardware and software to compensate for the computer's physical memory shortage, called virtual memory. 

4. What is the application of virtual memory?

Virtual memory is an OS scheme that uses hardware and software to optimize memory management and compensate for physical memory shortages by emulating RAM.