Dead-block prediction & dead-block correlating prefetchers

TLDR

Effective data prefetching requires accurate mechanisms to predict both which cache blocks to prefetch and when to prefetch them. This work introduces Dead‑Block Predictors to identify when a cache block becomes evictable and Dead‑Block Correlating Prefetchers to predict the next block to prefetch using address correlation. The predictors are trace‑based, using dead‑block detection for timing and address correlation for spatial prediction. Dead‑block prediction extends prefetch lookahead, allows direct placement into the last‑level cache, and eliminates auxiliary buffers, while the correlating prefetcher achieves effective prefetching across pointer‑intensive, integer, and floating‑point workloads.

Abstract

Effective data prefetching requires accurate mechanisms to predict both “which” cache blocks to prefetch and “when” to prefetch them. This paper proposes the Dead-Block Predictors (DBPs), trace-based predictors that accurately identify “when” an Ll data cache block becomes evictable or “dead”. Predicting a dead block significantly enhances prefetching lookahead and opportunity, and enables placing data directly into Ll, obviating the need for auxiliary prefetch buffers. This paper also proposes Dead-Block Correlating Prefetchers (DBCPs), that use address correlation to predict “which” subsequent block to prefetch when a block becomes evictable. A DBCP enables effective data prefetching in a wide spectrum of pointer-intensive, integer, and floating-point applications.