Virtual Memory

Definition

Virtual memory is a memory management capability that uses a combination of physical RAM and hard drive storage to provide a larger address space than the physical memory available.

How it Works

• When physical RAM is full, the operating system moves inactive pages of memory to a reserved space on the hard drive, known as the page file or swap space.
• When the system needs to access data that has been moved to the page file, it reads the data back into RAM.

Benefits

• Allows for larger programs to run than would fit in physical RAM.
• Enables multitasking by providing a larger address space.
• Helps to prevent out-of-memory errors.

Disadvantages

• Slower performance due to disk I/O.
• Can lead to thrashing if the system spends too much time swapping pages.

Key Concepts

• Page file: A reserved space on the hard drive used to store pages of memory that are not currently in use.
• Swap space: Another term for page file.
• Paging: The process of moving pages of memory between RAM and the page file.
• Thrashing: A situation where the system spends too much time swapping pages, leading to poor performance.

Importance

• Enables efficient use of physical RAM.
• Allows for running larger programs and multitasking.
• Helps to prevent system crashes due to out-of-memory errors.

Configuration

• Page file size: Can be adjusted to optimize performance.
• Location: Can be placed on a separate disk or partition for better performance.