Optimizing B^(+)-tree for hybrid memory with in-node hotspot cache and eADR awareness  

作　　者：Peiquan JIN Zhaole CHU Gaocong LIU Yongping LUO Shouhong WAN 

机构地区：[1]School of Computer Science and Technology,University of Science and Technology of China,Hefei 230027,China

出　　处：《Frontiers of Computer Science》2024年第5期133-145,共13页计算机科学前沿（英文版）

基　　金：This paper was supported by the National Natural Science Foundation of China(Grant No.62072419).

摘　　要：he advance in Non-Volatile Memory(NVM)has changed the traditional DRAM-onlymemorysystem.Compared to DRAM,NVM has the advantages of nonvolatility and large capacity.However,as the read/write speed of NVM is still lower than that of DRAM,building DRAM/NVM-based hybrid memory systems is a feasible way of adding NVM into the current computer architecture.This paper aims to optimize the well-known B^(+)-tree for hybrid memory.The novelty of this study is two-fold.First,we observed that the space utilization of internal nodes in B^(+)-tree is generally below 70%.Inspired by this observation,we propose to maintain hot keys in the free space within internal nodes,yielding a new index named HATree(Hotness-Aware Tree).The new idea of HATree is to use the unused space of the parent of leaf nodes(PLNs)as the hotspot data cache.Thus,no extra space is needed,and the in-node hotspot cache can efficiently improve query performance.Second,to further improve the update performance of HATree,we propose to utilize the eADR technology supported by the third-generation Intel Xeon Scalable Processors to enhance HATree with instant log persistence,which results in the new HATree-Log structure.We conduct extensive experiments on real hybrid memory architecture involving DRAM and Intel Optane Persistent Memory to evaluate the performance of HATree and HATree-Log.Three state-of-the-art indices for hybrid memory,namely NBTree,LBTree,and FPTree,are included in the experiments,and the results suggest the efficiency of HATree and HATree-Log.

关 键 词：hybrid memory B^(+)-tree hotspot in-node cache eADR 

分 类 号：TP333[自动化与计算机技术—计算机系统结构]