![]() ![]() The page table is where the operating system stores its mappings of virtual addresses to physical addresses, with each mapping also known as a page table entry (PTE). ![]() When a process requests access to data in its memory, it is the responsibility of the operating system to map the virtual address provided by the process to the physical address of the actual memory where that data is stored. ![]() Physically, the memory of each process may be dispersed across different areas of physical memory, or may have been moved ( paged out) to secondary storage, typically to a hard disk drive (HDD) or solid-state drive (SSD). In operating systems that use virtual memory, every process is given the impression that it is working with large, contiguous sections of memory. The page table is a key component of virtual address translation that is necessary to access data in memory. Virtual addresses are used by the program executed by the accessing process, while physical addresses are used by the hardware, or more specifically, by the random-access memory (RAM) subsystem. In the diagram above, some pages are not in physical memory.Ī page table is the data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses. Pages can be held on disk if seldom used, or if physical memory is full. Physical memory can contain pages belonging to many processes. Data structure that maps virtual addresses with physical addresses Relationship between pages addressed by virtual addresses and the pages in physical memory, within a simple address space scheme. ![]()
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