Os Memory Management Questions
Virtual memory management is a technique used by operating systems to provide the illusion of having more physical memory than is actually available. It involves the use of a combination of hardware and software mechanisms to map virtual addresses used by processes to physical addresses in the system's memory.
The process of virtual memory management can be described as follows:
1. Memory Allocation: When a process is created, it is allocated a certain amount of virtual memory space. This space is divided into fixed-size units called pages.
2. Page Table Creation: A page table is created for each process, which is a data structure that maps the virtual addresses used by the process to physical addresses in the system's memory. The page table is stored in the process's control block.
3. Page Fault Handling: When a process tries to access a virtual address that is not currently mapped to a physical address, a page fault occurs. The operating system handles this by bringing the required page from secondary storage (such as a hard disk) into physical memory.
4. Page Replacement: If physical memory is full and a new page needs to be brought in, the operating system selects a page to be evicted from memory. This is done using various page replacement algorithms, such as the least recently used (LRU) algorithm.
5. Memory Protection: Virtual memory management also provides memory protection by assigning different access permissions to different pages. This ensures that processes cannot access memory that they are not authorized to access.
6. Swapping: In cases where physical memory is still insufficient, the operating system can swap out entire processes or parts of processes to secondary storage to free up memory for other processes.
Overall, virtual memory management allows for efficient utilization of physical memory by allowing processes to use more memory than is physically available. It also provides memory protection and enables the efficient sharing of memory resources among multiple processes.