P-OPT: Practical Optimal Cache Replacement for Graph Analytics

Graph analytics is an important workload that achieves suboptimal performance due to poor cache locality. State-of-the-art cache replacement policies fail to capture the highly dynamic and input-specific reuse patterns of graph application data. The main insight of this work is that for graph applications, the transpose of a graph succinctly represents the next references of all vertices in a graph execution; enabling an efficient emulation of Belady's MIN replacement policy. In this work, we propose P-OPT, an architecture solution that uses a specialized compressed representation of a transpose's next reference information to enable a practical implementation of Belady's MIN replacement policy. Our evaluations across multiple applications and inputs reveal that P-OPT improves cache locality for graph applications providing an average performance improvement of 33% (56% maximum) over LRU replacement.