Virtual memory is a memory management technique that creates an “illusion” of a large, continuous memory space for programs, even if the physical RAM is limited.
- By using virtual memory, operating systems can run large applications or multiple programs simultaneously, exceeding the actual physical memory available.
- This technique makes systems more efficient and allows for better multitasking, providing a smoother user experience.
Advantages of Virtual Memory
- Memory Management Efficiency: Allows multiple processes to share the same memory space without interfering, improving overall memory utilization.
- Isolation and Security: Provides process isolation, meaning each program runs in its own protected address space, which helps prevent accidental or malicious interference.
- Larger Memory for Applications: Applications can use more memory than physically available, enabling complex or resource-intensive software to run on systems with limited RAM.
Disadvantages of Virtual Memory
- Performance Overhead: Memory management and swapping can create additional processing overhead, especially if excessive swapping (thrashing) occurs.
- Disk Space Requirements: Virtual memory requires a portion of the disk to act as swap space, reducing disk availability for other data.
- Complex Implementation: Managing virtual memory with paging, segmentation, and swapping adds complexity to OS design and may require additional hardware support (like MMU).
Types of Virtual Memory
In a computer, virtual memory is managed by the Memory Management Unit (MMU), which is often built into the CPU. The CPU generates virtual addresses that the MMU translates into physical addresses.
There are two main types of virtual memory:
- Paging
- Segmentation
