一句话：提出可移植缓存机制 METAL，解耦索引元数据与数据复用，通过 IX-Cache 和复用模式加速领域特定架构的稀疏索引访问。
领域特定架构（DSA）处理稀疏数据时需要索引数据结构的硬件支持。索引虽能节省空间并降低 DRAM 带宽，但其动态访问、指针追踪和遍历查找会膨胀工作集并造成缓存抖动，论文指出缓存组织本身是根因。METAL 是一种可移植缓存惯用法，使 DSA 能采用索引数据结构；它将索引元数据复用与数据复用解耦并独立优化。其两个核心思想是：IX-Cache 利用范围标签缩短索引遍历并减小工作集，从而权衡更宽索引节点与更靠近叶节点之间的取舍；复用模式提供显式缓存管理接口，在动态遍历不同索引区域时编排缓存插入与旁路。评估显示，METAL 相较流式 DSA 提升 7.8×、地址缓存提升 4.1×、先进 DSA 缓存提升 2.4×，并将 DRAM 能耗较先前最优降低 1.6×。
State-of-the-art domain specific architectures (DSAs) work with sparse data, and need hardware support for index data-structures [31, 43, 57, 61]. Indexes are more space-efficient for sparse-data, and reduce DRAM bandwidth, if data reuse can be managed. However, indexes exhibit dynamic accesses, chase pointers, and need to walk-and-search. This inflates the working set and thrashes the cache. We observe that the cache organization itself is responsible for this behavior. We develop METAL, a portable caching idiom that enables DSAs to employ index data-structures. METAL decouples reuse of the index metadata from data reuse, and optimizes it independently. We propose two ideas: i) IX-Cache: A cache that leverages range tags to short-circuits index walks, and reduces the working set. IX-cache helps capture the trade-off between wider index nodes that maximize reach vs those that are closer to leaf and minimize walk latency. ii) Reuse Patterns: An interface to explicitly manage the cache. Patterns orchestrate cache insertions and bypass as we dynamically traverse different index regions. METAL improves performance vs. streaming DSAs by 7.8×, address-caches by 4.1×, and state-of-the-art DSA-cache [50] by 2.4×. We reduce DRAM energy by 1.6× vs. prior state-of-the-art.
@inproceedings{KumarPBS24,
title = {METAL: Caching Multi-level Indexes in Domain-Specific Architectures},
author = {Anagha Molakalmur Anil Kumar and Aditya Prasanna and Jonathan Balkind and Arrvindh Shriraman},
booktitle = {ASPLOS},
year = {2024},
doi = {10.1145/3620665.3640402}
}