Virtual memory is a method of using secondary memory, consisting of both hardware and software as if it was a part of the primary one. The technique is widely used across modern operating systems, desktop, and mobile, because it lets computers expand the primary memory temporarily, making up for any insufficiencies with the physical one. Unfortunately, it’s not a magic wand. It can be an inexpensive upgrade and bring optimization, but also fleeting and slow.
That’s because the system must constantly transfer data to and from a form of storage such as HDD or SSD, which are sluggish in comparison. Now, let’s cover the advantages and disadvantages of virtual memory.
What is Virtual Memory?
We can understand if you are not sure which definition of Virtual Memory is correct. It is a concept that is known for confusing a lot of non-techy people.
Virtual memory is the capacity of an operating system to allow a computer to compensate for physical memory shortages. It does that by transferring the data from RAM to disk storage.
Once your computer runs out of RAM, you do not have to worry as this process is completely transparent. You will see your operating system shifting the data to an empty space on your hard drive or SSD. It will happen back and forth according to the situation.
There is a certain advantage and disadvantage when Virtual memory comes into play. It will help the system handle large workloads, but it will also lead to slower performance, as accessing data in RAM is faster as compared to a hard drive.
Advantages of virtual memory
Virtual memories are globally adopted in today’s operating systems, desktop, and mobile, and show no signs of stopping. To see why we will study the upsides of virtual memory. The following are the advantages of virtual memory:
1. It compensates for the lack of physical memory
The primary reason virtual memory has such a wide array of applications is the fact it can act as a temporary replacement for physical RAM. For now, you should know about two common ways of using virtual RAM in modern machines:
Though not always the case, modern desktop and laptop computers frequently use a paging file. Paging involves splitting virtual memory into many pages or paging files. This process also includes taking a predetermined portion of a hard drive (HDD, SSD, M.2, NVMe, and so on) and reserving it for virtual memory, also called a swap file. Then, when RAM gets full, any unused pages are moved to the hard disk drive, freeing up memory for necessary operations.
That way, it’s nearly impossible for a system to run out of memory. It’s also important to note that paging files have equal sizes and are determined by the hardware. We’ll explain FIFO (first-in, first-out), optimal algorithm, and LRU (Last Recently Used) page replacement methods another time.
Segmenting is a process akin to paging, but this time segments can have varying lengths and are user-determined and thus adjustable. The principle is identical. When the RAM gets full or reaches a threshold, unused segments move to the predetermined chunk of storage. Therefore, memory can be utilized for crucial tasks.
2. Virtual memory can be cheap or free*
While it may not be as powerful or as useful, when used as a complement to physical memory, its addition can be inexpensive. Getting virtual memory does not require any space, soldering, logistics, technological knowledge, or waiting time if you already have a compatible machine. It can be split into equal-size chunks or segmented and expanded up to a hardware limit.
Many users are unaware their operating systems even support the option, even if they have sufficient space and speedy storage. This means they can boost their hardware performance for free by enabling the technique (especially on mobiles).
3. It boosts multitasking and collaboration
As we pointed out, using virtual memory means users have access to more RAM than what the hardware allows. In other words, logical memory size is not limited by the physical one, meaning virtual memory can help execute processes whose memory demands exceed the systems.
This boosts the turnaround time. Plus, the aforementioned segments allow multiprogramming, i.e., multiple users or processes to use the same memory (“shared memory”) for better CPU and RAM utilization.
4. Virtual memory can prevent memory fragmentation
One of the benefits of virtual memory is that it does not need to contact the physical memory management unit. Virtual RAM lets users execute the segments needed for the program to run through individual mapping. That provides program data management, and memory is more likely to enter external fragmentation mode while paging. It also reduces the need for unnecessary I/O (input/output) devices.
5. Virtual memory can enhance data security
The memory management system unit of a computer keeps track of physical and virtual addresses in page tables. That means that memory swapped has an extremely low chance of having data loss during paging. Segment tables do the same job.
Further, virtual memory brings memory isolation, i.e., a mechanism that isolates process memory from the kernel and any other processes, preventing spying or data manipulation.
Disadvantages of virtual memory
While virtual memory can be drastically larger, hard to overload, and easier to obtain than physical, it has a set of downsides. The following are the disadvantages of virtual memory:
1. It may take up precious storage space
We understand users would usually pick enhanced performance over storage capacity loss, but that isn’t always the case. Luckily, modern storage devices are growing in capacity, speed, durability, and mapping address procedures while down in price. Thus, this is an issue on paper nowadays.
2. Virtual memory is slower than physical RAM
Regardless of the type of configuration, physical RAM is drastically faster than virtual memory on internal storage. If used on external storage, the situation gets worse and reduces the lifespan due to constant writing and reading. That is due to their nature, and cannot be avoided, so applications that rely entirely on virtual memory will take longer to execute.
3. Switching between applications may require extra time
Physical RAM is designed for speed and versatility, which includes balancing processes at once. Virtual memory is optimized to help switch between high-priority and low-priority processes to improve performance. That adds a slight delay, which can worsen if low-speed storage is used for paging and segmenting.
4. It may cause stability problems
You could’ve seen this coming. Though impressive, the fact you can execute a program whose requirements exceed the hardware memory capabilities can also mean occasional instability or crash. Additionally, through page-fault rate, the time spent on page swapping out and in, can exceed that of program execution. In the base case, it will cause sluggish performance.
5. Virtual memory is prone to marketing schemes
With everything stated so far, it’s clear that the truth can be embellished in the wrong hands. With a global market and the constant growth of electronics, many manufacturers use fine print and clever wording to make their devices sound too good to be true.
After all, 8 GB of RAM without a drastic price hike sounds much better than 4 GB of physical RAM plus 4 GB of virtual memory on the specs sheet. Customers later discover that what’s on paper doesn’t translate to real-life performance.
Common Uses of Virtual Memory
Learning more about Virtual memory will not only increase your knowledge, but will also help you with your computer stuff. Having such information can help you out during crucial moments. The more you learn about computers these days, the better it is for your future. So, let us have a look at some of Virtual Memory’s common uses:
- Memory Management: The main goal of virtual memory is to allow an operating system to use hard disk space to simulate extra memory. It is a good thing when you have to run multiple programs simultaneously. And if you have limited physical memory, you can use this feature of virtual memory.
- Efficient Use of RAM: Virtual memory allows you to make the most out of the RAM. It helps you do that by keeping only the most important parts of Random Access Memory. It moves the rest of the unimportant parts to the disk storage, which you can later retrieve whenever you need to.
- Protection: A lot of people are not often aware of the protection provided by Virtual memory. Virtual memory is very handy when it comes to providing a level of protection and isolation between processes. It ensures one program does not overwrite the memory of another.