Sivunkorvausalgoritmi

Sivunkorvausalgoritmi, or page replacement algorithm, is a crucial concept in operating systems memory management. Its primary function is to decide which page in the main memory should be swapped out to secondary storage when a new page needs to be loaded and the memory is already full. This process is essential for virtual memory systems, which allow programs to use more memory than physically available by temporarily storing less frequently used data on disk.

The goal of a page replacement algorithm is to minimize the number of page faults, which occur when a requested page is not found in main memory, requiring a disk access. Different algorithms employ various strategies to predict which page is least likely to be needed in the near future.

Commonly used algorithms include First-In, First-Out (FIFO), which removes the oldest page regardless of its usage. Least Recently Used (LRU) is another popular choice, evicting the page that has not been accessed for the longest time. Optimal page replacement, though theoretically ideal, is impractical as it requires future knowledge. Other algorithms like Clock and variations of LRU aim to approximate LRU behavior with less overhead. The choice of algorithm can significantly impact system performance, affecting the overall speed and efficiency of program execution.