CCCPO: Robust Prefetcher Optimization Technique Based on Cache Convection

Abstract

One of the significant issues of processor architecture is to overcome memory latency. Prefetching can greatly improve cache performance, however, it has the drawback of cache pollution unless its aggressiveness is properly set. Although several techniques for prefetcher throttling have been proposed which use accuracy as a metric, their robustness were not sufficient due to the variations between program working set sizes and cache capacities. In this paper, we revisit cache behavior with the viwepoint of data lifetime in a cache with prefetching. Based on this observation Cache-Convection-Control-based Prefetch Optimization (CCCPO) is proposed, which exploits the characteristics of cache line reuse and controls the prefetcher aggressiveness.Evaluation results showed that this novel approach achieved 4.6% improvement against the most recent prefetcher throttling algorithms in the geometric mean of SPEC CPU 2006 benchmark suite with 256KB LLC.

Using Cacheline Reuse Characteristics for Prefetcher Throttling

“…The most recent related studies are implemented and evaluated for comparison purposes [12], [14], [17]. Feedback Di- rected Prefetching (FDP) and Coordinated Prefetcher Throttling (CPT) are both throttling techniques that are guided by prefetcher performance.…”

“…Previously, we proposed CCCPO, which exploits CC to determine the prefetcher aggressiveness [16], [17]. In this technique, CC is calculated periodically, and the prefetcher aggressiveness is set to indicate higher CC.…”