Operating System 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 works by utilizing a combination of the computer's physical memory (RAM) and secondary storage (usually a hard disk) to create an extended virtual address space.
When a program is executed, it is divided into smaller units called pages. These pages are loaded into the physical memory as needed. However, if the physical memory is insufficient to hold all the required pages, the operating system transfers some of the less frequently used pages to the secondary storage, freeing up space in the physical memory.
The operating system keeps track of the pages in both physical memory and secondary storage using a page table. This table maps the virtual addresses used by the program to the corresponding physical addresses in memory or secondary storage.
When a program accesses a virtual address that is not currently in the physical memory, a page fault occurs. The operating system then retrieves the required page from secondary storage and loads it into the physical memory. This process is transparent to the program, as it continues to operate under the assumption that all the required pages are in the physical memory.
By using virtual memory, the operating system can effectively manage the limited physical memory resources and allow programs to run even if they require more memory than is physically available.