PP-Bridge: Establishing a Bridge between the Prefetching and Cache Partitioning

Abstract

— Modern computer processors are equipped with multiple cores, each boasting its own dedicated cache memory, while collectively sharing a generously sized Last Level Cache (LLC). To ensure equitable utilization of the LLC space and bolster system security, partitioning techniques have been introduced to allocate the shared LLC space among the applications running on different cores. This partition dynamically adapts to the requirements of these applications. Prefetching plays a vital role in enhancing cache performance by proactively loading data into the cache before it get requested explicitly by a core. Each core employs prefetch engines to decide which data blocks to fetch preemptively. However, a haphazard prefetcher may bring in more data blocks than necessary, leading to cache pollution and a subsequent degradation in system performance. To maximize the benefits of prefetching, it is essential to keep cache pollution to a minimum. Intriguingly, our research has uncovered that when existing prefetching techniques are combined with partitioning methods, they tend to exacerbate cache pollution within the LLC, resulting in a noticeable decline in system performance. In this paper, we present a novel approach aimed at mitigating cache pollution when combining prefetching with partitioning techniques.