Leheküljeviga

Leheküljeviga is an Estonian term that translates to "page fault" in English. It refers to an error condition that occurs when a program tries to access a memory page that is not currently loaded into physical memory. In modern operating systems, memory is managed in units called pages. When a program needs data or instructions from a memory page, it makes a request to the memory management unit. If the requested page is not present in RAM, a page fault is generated.

The operating system's memory manager then handles this page fault. It typically involves locating the required page on secondary storage, such as a hard drive or SSD. The operating system then loads this page into an available slot in physical memory. If there are no free slots, it may need to swap out another page, moving it back to secondary storage to make space. Once the required page is loaded into memory, the program can resume its execution, accessing the data it needs.

While page faults are a normal part of memory management and are handled by the operating system, a high number of page faults, often referred to as excessive paging or thrashing, can significantly slow down system performance. This indicates that the system is spending too much time swapping data between RAM and storage, rather than executing program instructions. This can be caused by insufficient RAM for the running applications or inefficient memory usage by the programs themselves.