The Problem of Wasted Prefetches

In data storage systems, the disks are typically the bottleneck. If pages are prefetched speculatively and are not subsequently used, then not only does this cause cache pollution and increase in the backend bandwidth usage, but more importantly, it causes additional I/O load on the disks. This additional load can lead to degradation in performance, defeating the purpose of prefetching. This is the reason why most history-based prefetching schemes which do not have high prediction accuracy are not used in commercial systems.