Virtual memory is a computer system technology that allows a program to exceed the size of the main physical memory.
That’s why it’s called virtual because it doesn’t exist in reality; instead, it’s just an illusion created by the operating system and hardware.
This article will give you a deeper understanding of virtual memory, why we need virtual memory systems, how they work and how they differ from physical memory systems.
Examples of Virtual Memory
Virtual memory is a term used to describe an address space larger than the amount of RAM available.
It allows your computer to temporarily store data outside of physical RAM or Random Access Memory to make more room for you to use.
Virtual memory works because when there isn’t enough physical RAM available for your programs, they will start accessing inactive regions in virtual memory instead of active ones.
When they need something from these inactive regions they have previously accessed through virtual memory, they’re moved back into active ones so that other processes can use them too!
What is Virtual Memory Used For?
Virtual memory allows the processor to address more than the physical memory available at any given time. This is done by using a portion of the hard disk as if it was RAM, but with some limitations.
The main advantage of virtual memory is speed. Because all data is copied from disk to RAM and back to disk. There’s no need for lengthy operations such as loading data into registers or out of registers (for example, when accessing an array element).
This saves a lot of time when processing large amounts of data in applications like databases or scientific simulations.
Another primary use of virtual memory allows more efficient allocation algorithms than those based on contiguous blocks.
Instead, a program can request any amount of memory needed at that moment by calling VirtualAlloc(…), which will allocate just enough physical pages needed for this purpose (or none if all page frames are already occupied).
This way, over-commitment doesn’t lead to fragmentation problems with huge waste potential (as seen before).
Finally, another exciting application area worth mentioning here would be protection against buffer overflows: since each process has its own address space where only accesses within this range are permitted by default.
One can easily prevent an attacker from overflowing buffers into other processes’ address spaces by restricting their permissions correctly, preventing him from overwriting critical parts inside your process!
Virtual Memory vs. Physical Memory
Virtual memory is a solution to the problem of limited physical memory in your computer. Virtual memory uses virtual addresses and page tables to dynamically allocate and deallocate portions of physical memory, allowing for more efficient use of RAM.
Virtual memory allows programs to execute even when there is insufficient real storage (e.g., when you run out of disk space). This means that an application can hold data in virtual memory stored on a disk instead of in RAM.
When the application needs access to this data again, it pulls it back into RAM, where the processor can run along with it. This process happens seamlessly behind the scenes so that users don’t notice anything different—even though they’re using much less hard drive space than if all their files were stored directly within their executable application files!
In other words: You need both real (physical) and virtual (created by software) memory inside your PC so that programs can generally operate without having constant issues due to a lack of resources needed by them being available at any given time.
Virtual Memory in an Operating System
The virtual address space is the total of all accessible memory locations, including physical, shared, and private. The operating system maps the user’s process image into this range, allowing it to access memory regions outside of its own.
A process that has been mapped into any given range may not be able to access other ranges independently but can do so via system calls or library calls.
The contents of a process virtual address space are determined at process creation time by the operating system based on what physical resources are available and what permissions have been granted by the user or administrator (if they exist).
Virtual Memory in Computer Architecture
Virtual memory is a system in which data addresses are mapped to physical memory addresses. This allows programs to access more memory than is physically available on the computer.
Virtual memory allows multiple processes to be placed in RAM, which increases their overall size.
Virtual memory reduces the number of times the operating system has to swap processes between disk and RAM and improves performance because running processes are generally faster than swapped-out ones.
Virtual memory can help improve system performance, preventing applications from being idle while waiting for data from storage devices.
Hence, they are free to use their processing power elsewhere while they wait instead of just sitting there not doing anything until it finishes loading up everything else first (which would slow down overall performance).