Ginkgo: A Learned Index Enhanced Tiered Memory System

Abstract

Compute Express Link (CXL), as an emerging high-speed interconnect protocol, offers a promising approach to memory expansion. Organizing fast DDR DRAM and large CXL memory as a tiered memory system is preferred to obtain the large memory capacity while maintaining high memory performance. Additionally, such a tiered memory system also adopts huge pages to alleviate address translation overhead. However, due to memory bloating issues in huge pages, existing hardware-based tiered memory management systems suffer from severe cache conflicts and DDR DRAM underutilization, resulting in significant performance degradation. We introduce Ginkgo, a learned-index enhanced tiered memory system, which builds a distribution-aware cache index mechanism while leveraging the learned index to minimize metadata overhead. Evaluation reveals that Ginkgo reduces average memory access latency with an average of 3.1% and 13.5% compared to state-of-the-art Alloy Cache and Unison Cache, respectively.

Publication
In IEEE Micro
Xiran Yang
Xiran Yang
Ph.D Student
Chuandong Li
Chuandong Li
Ph.D Student
Jianqiang Zeng
Jianqiang Zeng
Ph.D Student
Diyu Zhou
Diyu Zhou
Professor
Xiaolin Wang
Xiaolin Wang
Professor
Zhenlin Wang
Zhenlin Wang
Professor
Yingwei Luo
Yingwei Luo
Professor