Os Process Management Questions Medium
Paging is a memory management technique used in operating systems to implement virtual memory. It allows the operating system to divide the physical memory into fixed-size blocks called pages and the logical memory into equal-sized blocks called page frames. The size of a page is typically a power of 2, such as 4KB or 8KB.
When a process is loaded into memory, it is divided into smaller units called pages. These pages are then mapped to available page frames in the physical memory. The mapping is maintained in a data structure called the page table, which keeps track of the correspondence between logical addresses and physical addresses.
When a process references a memory location, the virtual address generated by the CPU is divided into a page number and an offset within the page. The page number is used to index the page table, which provides the corresponding physical page frame number. The offset is used to locate the specific byte within the page frame.
If the required page is not present in the physical memory, a page fault occurs. The operating system then retrieves the required page from the secondary storage (usually the hard disk) and brings it into an available page frame in the physical memory. The page table is updated to reflect the new mapping.
Paging allows for efficient memory allocation and utilization. It enables processes to be larger than the available physical memory by storing less frequently used pages on the secondary storage. This results in better overall system performance as the operating system can effectively manage the limited physical memory resources.
However, paging also introduces overhead due to the need for frequent page table lookups and the possibility of page faults. To mitigate these issues, operating systems employ various techniques such as TLB (Translation Lookaside Buffer) caching and page replacement algorithms to optimize the paging process and minimize the impact on system performance.