Prefetch circuit with global quality factor to reduce aggressiveness in low power modes

Abstract

A prefetch circuit may include a memory, each entry of which may store an address and other prefetch data used to generate prefetch requests. For each entry, there may be at least one 'quality factor' (QF) that may control prefetch request generation for that entry. A global quality factor (GQF) may control generation of prefetch requests across the plurality of entries. The prefetch circuit may include one or more additional prefetch mechanisms. For example, a stride-based prefetch circuit may be included that may generate prefetch requests for strided access patterns having strides larger than a certain stride size. Another example is a spatial memory streaming (SMS)-based mechanism in which prefetch data from multiple evictions from the memory in the prefetch circuit is captured and used for SMS prefetching based on how well the prefetch data appears to match a spatial memory streaming pattern.