Computer Architecture Questions
Virtual memory is a memory management technique used by operating systems to provide the illusion of having more physical memory than is actually available. It allows programs to use more memory than what is physically installed in the computer by utilizing a combination of RAM and disk storage.
In virtual memory, the operating system divides the memory into fixed-size blocks called pages. These pages are then mapped to corresponding blocks in the secondary storage, such as the hard disk. When a program requests memory, the operating system allocates a certain number of pages from the secondary storage and loads them into the physical memory (RAM).
The mapping between the virtual memory and physical memory is maintained in a data structure called the page table. This table keeps track of which pages are currently in the physical memory and their corresponding locations in the secondary storage.
When a program accesses a memory location that is not currently in the physical memory, a page fault occurs. The operating system then retrieves the required page from the secondary storage and replaces a less frequently used page in the physical memory with the requested page. This process is known as page swapping or paging.
By using virtual memory, the operating system can effectively manage the limited physical memory resources and allow multiple programs to run simultaneously without the need for each program to have its own dedicated physical memory. It also provides memory protection and isolation between different programs, ensuring that one program cannot access or modify the memory of another program.