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What is Virtual Memory?
Virtual memory typically refers to a specific type of memory management technique used to provide additional memory to the hard drive of the computer. Actually, it is the method of using secondary memory as a part of main memory.
From a technical point of view, it is the method in which parts of the memory are stored on the hard drive. These sections are called the pages, which are loaded onto the real memory address as and when it is requested.
- Virtual memory refers to the block of space on the hard drive or a Solid State Drive usually assigned by the operating system.
- This memory simulates the RAM when its physical amount runs short for active programs. It supplies ‘fake’ RAM to them so they can remain running.
- Virtual memory is important for a computer to work since it optimizes its efficiency and speed.
- Using virtual memory is a much more cost-effective alternative to adding new RAM to a computer system in order to create and manage storage space.
- Relying too much on the virtual memory is not endorsed because it may result in a loss of performance since it is slower than the physical RAM.
Understanding Virtual Memory
In simple terms, virtual memory is a specific feature of the operating system that compensates for the deficiencies in the physical memory of the computer system by using both hardware and software.
This is a specific feature of the operating system which is available on:
The working process of the virtual memory is typically temporary, and it involves swapping addresses between the RAM and the hard disk.
- When the physical memory runs low on space, data is moved from it to the paging file, which frees up the space and allows the computer to complete the given function.
- The processes are transferred between the hard disk and the RAM of the computer by copying them.
- During copying virtual memory into physical memory, it is divided by the operating system by a fixed number of addresses into either swap files or page files.
- When needed by the computer, the files are swapped back again to make them available in the RAM.
When you receive any message saying that the virtual memory is running low, you will need to do any one of the following:
- Add more RAM.
- Increase the size of the paging file.
In the Windows systems, this virtual memory is managed automatically, but it can also be done manually, provided that the default size of the virtual memory is not substantially large.
Types of Virtual Memory
Usually, there are two major types of virtual memory methods used by the memory management systems for improving the performance of the applications namely, paging and segmentation.
In this method, the RAM is divided into different segments or blocks, usually referred to as pages, each of 4K in size.
The processes are allocated these pages, which is enough to meet their memory requirements.
The pages are usually swapped between the page file and the RAM, in normal conditions. However, there is a chance that the memory will be wasted if the exact requirement of the process is not known and the entire page is not used.
In this method, segments of varying lengths are used instead of fixed sizes and allocated to processes so that they meet their exact requirements.
There is no wasted memory in this process, where the applications are divided into logically autonomous address spaces. This makes sharing them much easier and more secure.
However, the varying sizes of the segments may result in memory fragmentation, and the scattered chunks resulting from continuous allocation and deallocation may be too small to be useful. If they build up, allocation would be difficult.
The operating system will have a hard time keeping track of all these small segments, each of which needs using several segments.
This will make the system inefficient and lower the overall performance of the application.
Why Use Virtual Memory?
The main reason to use virtual memory is to deal with the situations when the computer system or a current program or set of programs runs short of physical memory and ceases to function.
Acting as a secondary memory, the operating system considers it to be a part of the main memory and therefore the program can continue running.
Actually, these addresses map the addresses of the programs into the addresses of the RAM so that these can be used for mapping onto the disk when there is no more space available.
The most significant use of these virtual addresses is that they allow the operating system to:
- Load programs that are larger in size than the actual physical memory available
- Provide memory protection and data security even if several programs access the same address due to different mappings
- Share codes easily
- Eliminate the need to keep several copies of the codes
- Map different addresses on the same location of the physical memory
- Load a number of programs into the main memory
- Offer location independence to the data so that it can be stored anywhere in the main memory
- Reduce the effects of errors and memory fragmentation since the data space does not need to be continuous
- Facilitate debugging
- Multitask easily
- Check various features including null pointers and unallocated memory
- Help the operating system avoid reading from and writing to the reserved addresses
In short, the virtual memory is used to help the operating system in avoiding a lot of issues during operation.
Is It Good to Increase Virtual Memory?
To put it simply, it is not needed to increase or even decrease the virtual memory setting in general because it will affect the working of a program.
Since the speed of RAM is higher than that of the virtual memory, using more of the latter will reduce the operational speed of the system instead of improving it.
It is true that managing virtual memory is quite easy, but it is not necessary because it may put the system at the risk of:
- Poor optimization of software
- A memory leak issue
- Future malfunctions
Typically, a Windows system will itself make the necessary adjustments to the virtual memory as and when needed on the fly, depending on the amount of installed RAM in the system and usage spikes.
This self-adjusting feature prevents the system from taking up a large space unnecessarily.
Still, some users may increase or decrease the virtual memory setting due to the following reasons:
- They feel that there is enough RAM installed in their computer systems and so the virtual memory is not needed by the operating system for its operation.
- They want to have more space on their hard drives and think that the virtual memory is wasting a lot of it, adding to the cost.
However, if you decrease or even eliminate the virtual memory with the intention of freeing up more space on your hard drive, it may result in some specific errors or make the system unstable.
Therefore, any manual adjustments made to the virtual memory settings should be made at your own risk.
Typically, you should not try to do it if you do not absolutely need to do it and do not have firm guidelines about it.
Therefore, it is good to leave it in place as it is and let the system use virtual memory as much as it can.
- It allows running more programs on the same system at the same time, increasing the overall efficiency of the system.
- It allows running larger applications even on systems without a large amount of RAM in them.
- It is a less expensive way to increase memory than adding more RAM.
- It allows increasing memory in a system with enough RAM that its operating system and hardware can support.
- It prevents the applications from competing with each other for the shared memory space.
- It allows core procedures to share memory between libraries containing written code and provides the foundation for their operations.
- It improves data security and memory protection by segmenting and isolating addresses where information is stored.
- It provides the right amount of main and virtual memory to the computer systems, thereby lowering the cost.
- It helps in optimizing the usage of the Central Processing Unit (CPU).
- The performance is not at the same level as the physical RAM.
- It can affect the performance of the system negatively, resulting in slowdowns.
- It consumes crucial storage space, which could have been used otherwise for long-term storage of data.
- The speed of virtual memory is quite slow.
- The amount of virtual memory depends on the amount of secondary storage in the computer.
- It can cause disk thrashing if the amount of RAM in the computer is small.
- Applications may take longer time to load while swapping using a virtual memory.
- Additional hardware support is necessary for address translations during mapping data between virtual memory and physical memory, which slows down the system even further.
Virtual Memory Vs Physical Memory
- Virtual memory is a kind of a logical memory, but in comparison, the physical memory is the actual space on the hard drive dedicated especially to the RAM on the motherboard of the computer.
- Virtual memory is slower in comparison to the physical memory in terms of performance.
- When it comes to cost, using virtual memory rather than physical memory to increase storage space is less costly.
- The computer system always uses the physical memory first and then uses the virtual memory if the RAM is full.
- Increasing virtual memory is restricted by and subject to the size of the hard drive of the computer system, but in comparison, adding RAM depends on the other components in it and the support provided by them.
- The virtual memory does not have direct access to the Central Processing Unit of the computer system. On the other hand, the physical memory can access the CPU directly.
- The virtual memory uses the paging technique for its operation, but in comparison, the physical memory implements the swapping techniques for functioning.
Examples of Virtual Memory
One of the most common instances of using a virtual memory is when you run several applications or programs at the same time on your computer system.
It can be loading your emails in the browser window while running the word processing software at the same time or shifting content management system and scheduling software.
Is Virtual Memory Always Used?
Yes, it is used always. You can say that virtual memory is used even when the total amount of memory needed by all of the current processes is not more than the amount of Random Access Memory (RAM) installed in the computer system.
It is only the main parts of the kernel of an operating system that can bypass the virtual address translation and directly use the addresses of the real memory instead.
So, now you know how virtual memory helps in dealing with the deficit in storage space on the hard drive more efficiently by transferring pages of data from the RAM to the hard disk storage.
The method uses both software and hardware for the process and is available on almost all major types of operating systems.