Sivunvirhe

Sivunvirhe is a Finnish term that translates to "page fault" in English. It is a crucial concept in computer operating systems, specifically within memory management. A page fault occurs when a program attempts to access data or code that is not currently present in the main memory (RAM). This can happen for several reasons, such as when the data is stored on secondary storage (like a hard drive or SSD) and needs to be loaded, or when the program tries to access a memory location it doesn't have permission to access.

When a page fault is triggered, the operating system's memory manager takes control. It first determines the cause of the fault. If the required data is on secondary storage, the operating system locates it, loads it into an available page frame in RAM, and updates the program's page table to reflect the new memory location. The program can then resume execution as if the data had always been in RAM. If the page fault is due to a protection violation, the operating system might terminate the program.

Page faults are a normal and expected part of virtual memory systems. They allow operating systems to use more memory than physically available by swapping less frequently used data between RAM and secondary storage. While necessary for efficient memory management, frequent page faults, often referred to as "thrashing," can significantly degrade system performance as the processor spends too much time moving data instead of executing instructions. Therefore, minimizing page faults is a common goal in optimizing software and system configurations.