sivuvälimuistissa

Sivuvälimuisti, or page cache, is a memory management technique used in operating systems to improve system performance by reducing the need to access slower main memory or disk storage. It stores recently accessed or frequently used pages of data in faster RAM.

When a program requests data, the operating system first checks the page cache. If the data is found in the cache, known as a cache hit, it can be retrieved much faster than if it had to be fetched from secondary storage. This significantly speeds up program execution and overall system responsiveness.

If the requested data is not in the cache, a cache miss occurs. In this scenario, the operating system retrieves the data from its original source (e.g., hard drive) and also copies it into the page cache for potential future use. To manage the limited space within the cache, various replacement algorithms are employed, such as Least Recently Used (LRU), to decide which pages to evict when new data needs to be brought in.

The effectiveness of the page cache depends on factors like the amount of available RAM, the working set of the running applications, and the efficiency of the caching algorithm. A well-tuned page cache can dramatically improve the performance of I/O-bound operations and applications that repeatedly access the same data.