ISSN 1000-1239 CN 11-1777/TP

计算机研究与发展 ›› 2021, Vol. 58 ›› Issue (2): 397-405.doi: 10.7544/issn1000-1239.2021.20200381

所属专题: 2021大数据时代的存储系统与智能存储技术专题

• 系统结构 • 上一篇    下一篇

一种多核友好的持久性内存键值系统

汪庆,朱博弘,舒继武   

  1. (清华大学计算机科学与技术系 北京 100084) (q-wang18@mails.tsinghua.edu.cn)
  • 出版日期: 2021-02-01

A Multicore-Friendly Persistent Memory Key-Value Store

Wang Qing, Zhu Bohong, Shu Jiwu   

  1. (Department of Computer Science and Technology, Tsinghua University, Beijing 100084)
  • Online: 2021-02-01

摘要: 相比于传统内存,持久性内存具有容量大和非易失的特点,这为构建大规模键值存储系统提供了新的机遇.然而,在多核服务器架构下设计持久性内存键值系统面临着诸多挑战,包括并发控制带来的CPU缓存抖动、对持久性内存有限写带宽的消耗和竞争以及持久性内存高延迟带来的线程冲突加剧.提出一种多核友好的持久性内存键值系统(multicore-friendly persistent memory key-value store, MPKV),通过设计高效并发控制方法和减少对持久性内存的写操作,充分提高多核并发性能.为避免锁资源带来的额外持久性内存写带宽消耗,MPKV引入了易失性锁管理机制,将写锁资源从索引中分离,在DRAM(dynamic RAM)中单独维护它们.为保证崩溃一致性和提高并发查询性能,MPKV引入了2阶段原子写机制,利用CPU提供的原子写操作指令将系统从一个一致性状态原子地切换到另一个一致性状态,并支持了无锁查询.基于易失性锁管理机制,MPKV还提出一种并发写消除机制,以提高更新操作之间的并发效率.当出现2个冲突的更新操作时,并发写消除机制让其中一个操作直接返回,不做任何持久性内存的分配与写操作.实验显示,MPKV相比于pmemkv具有更良好的性能以及多核扩展性.其中,在18线程环境下,MPKV的吞吐达到pmemkv的1.7~6.2倍.

关键词: 持久性内存, 多核架构, 键值系统, 并发控制, 崩溃一致性

Abstract: Compared with traditional memory, i.e., DRAM, persistent memory has the characteristics of large capacity and non-volatility, which brings new opportunities for building large-scale persistent memory key-value store systems. However, designing a persistent memory key-value store under a multicore server architecture faces many challenges, including CPU cache thrash due to concurrency control, the consumption and competition of limited write bandwidth for persistent memory, and aggravated conflicts between threads caused by high latency of persistent memory. In this paper, MPKV, a multicore-friendly persistent memory key-value store is proposed. By designing efficient concurrency control methods and reducing write operations to persistent memory, the system’s multicore concurrency performance is fully improved. To avoid the extra persistent memory write bandwidth consumption caused by lock resources, MPKV introduces a volatile lock management mechanism to separate write lock resources from indexes and maintain them separately in DRAM. To ensure crash consistency and improve concurrent query performance, MPKV introduces a two-phase atomic write mechanism, which uses the atomic write operation instructions provided by the CPU to atomically switch the system from one consistent state to another consistent state, and further supports lock-free query. Based on the volatile lock management mechanism, MPKV also introduces a concurrent write elimination mechanism to improve the efficiency of concurrency between update operations. When two conflicting update operations occur, the concurrent write elimination mechanism allows one of the operations to return directly without any persistent memory allocation and write. Experiments show that MPKV has better performance and multicore scalability than pmemkv. Specifically, in the 18-thread environment, the throughput of MPKV reaches 1.7 to 6.2 times of pmemkv.

Key words: persistent memory, multicore architecture, key-value store, concurrency control, crash consistency

中图分类号: