Design and Performance of a General-Purpose Software Cache

This paper discribes a General-Purpose Software cache (GPS cache) which can improve the performance of many applications including Web servers and databases. It can service several hundred thousand cache hits per second on a uniprocessor. When used to cache data for a Web server, the overhead due to a GPS cache is insignificant compared to the overhead of the Web server. The GPS cache can store objects in memory, on disk, or both. The cache uses a new algorithm for managing expiration times of cached objects which is more efficient than previous ones. The GPS cache uses Data Update Propagation (DUP) to invalidate complex objects which is crucial for caching and maintaining updated copies of dynamic Web pages. Transactions can be logged using different buffering mechanisms in order to provide a balance between efficiency and updated transaction log files.