Relative Performance of a Multi-level Cache with Last-Level Cache Replacement: An Analytic Review

TL;DR

This paper reviews the performance of various cache replacement policies in multi-level cache hierarchies, emphasizing the differences between inclusive and exclusive last-level caches and their impact on overall system efficiency.

Contribution

It provides an analytic review of existing cache replacement techniques for last-level caches, highlighting their performance implications in multi-application environments.

Findings

Inclusive LLCs may suffer from inefficiencies due to shared cache conflicts.

Exclusive LLCs demand more sophisticated replacement policies for optimal performance.

Different replacement strategies significantly affect cache hit rates and memory bandwidth utilization.

Abstract

Current day processors employ multi-level cache hierarchy with one or two levels of private caches and a shared last-level cache (LLC). An efficient cache replacement policy at LLC is essential for reducing the off-chip memory transfer as well as conflict for memory bandwidth. Cache replacement techniques for inclusive LLCs may not be efficient for multilevel cache as it can be shared by enormous applications with varying access behavior, running simultaneously. One application may dominate another by flooding of cache requests and evicting the useful data of the other application. From the performance point of view, an exclusive LLC make the replacement policies more demanding, as compared to an inclusive LLC. This paper analyzes some of the existing replacement techniques on the LLC with their performance assessment.