基于DRAM的内存子系统在容量不断增大的过程中消耗了40%的能量。相变随机访问存储器PRAM(phase-change random access memory)作为潜在的替代品可以解决内存容量和能耗的问题。然而,PRAM存在写操作寿命有限和带宽较低等问题。为此提出了...基于DRAM的内存子系统在容量不断增大的过程中消耗了40%的能量。相变随机访问存储器PRAM(phase-change random access memory)作为潜在的替代品可以解决内存容量和能耗的问题。然而,PRAM存在写操作寿命有限和带宽较低等问题。为此提出了的Shift-Min-Write机制,通过减少写操作流量达到延长写操作寿命和增加写带宽的目的。实验结果证明:与传统方法相比,新方法可以增加写带宽和写寿命1倍以上,并减少大约60%的写操作,而且不会随字宽增大而有明显的退化。展开更多
The recently proposed learned index has higher query performance and space efficiency than the conventional B+-tree.However,the original learned index has the problems of insertion failure and unbounded query complexi...The recently proposed learned index has higher query performance and space efficiency than the conventional B+-tree.However,the original learned index has the problems of insertion failure and unbounded query complexity,meaning that it supports neither insertions nor bounded query complexity.Some variants of the learned index use an out-of-place strategy and a bottom-up build strategy to accelerate insertions and support bounded query complexity,but introduce additional query costs and frequent node splitting operations.Moreover,none of the existing learned indices are cache-friendly.In this paper,aiming to not only support efficient queries and insertions but also offer bounded query complexity,we propose a new learned index called COLIN(Cache-cOnscious Learned INdex).Unlike previous solutions using an out-of-place strategy,COLIN adopts an in-place approach to support insertions and reserves some empty slots in a node to optimize the node’s data placement.In particular,through model-based data placement and cache-conscious data layout,COLIN decouples the local-search boundary from the maximum error of the model.The experimental results on five workloads and three datasets show that COLIN achieves the best read/write performance among all compared indices and outperforms the second best index by 18.4%,6.2%,and 32.9%on the three datasets,respectively.展开更多
The emergence of non-volatile memory(NVM)has introduced new opportunities for performance optimizations in existing storage systems.To better utilize its byte-addressability and near-DRAM performance,NVM can be attach...The emergence of non-volatile memory(NVM)has introduced new opportunities for performance optimizations in existing storage systems.To better utilize its byte-addressability and near-DRAM performance,NVM can be attached on the memory bus and accessed via load/store memory instructions rather than the conventional block interface.In this scenario,a cache line(usually 64 bytes)becomes the data transfer unit between volatile and non-volatile devices.However,the failure-atomicity of write on NVM is the memory bit width(usually 8 bytes).This mismatch between the data transfer unit and the atomicity unit may introduce write amplification and compromise data consistency of node-based data structures such as B+-trees.In this paper,we propose WOBTree,a Write-Optimized B+-Tree for NVM to address the mismatch problem without expensive logging.WOBTree minimizes the update granularity from a tree node to a much smaller subnode and carefully arranges the write operations in it to ensure crash consistency and reduce write amplification.Experimental results show that compared with previous persistent B+-tree solutions,WOBTree reduces the write amplification by up to 86× and improves write performance by up to 61× while maintaining similar search performance.展开更多
文章研究了使用Oracle Active Data Guard实现PMS2.0数据库读写分离。生产管理系统PMS是电力信息系统中重要的核心业务系统,随着数据量不断快速增长,数据库的I/O吞吐量以及资源的耗用愈发凸显性能瓶颈,造成业务用户并发操作延时甚至失...文章研究了使用Oracle Active Data Guard实现PMS2.0数据库读写分离。生产管理系统PMS是电力信息系统中重要的核心业务系统,随着数据量不断快速增长,数据库的I/O吞吐量以及资源的耗用愈发凸显性能瓶颈,造成业务用户并发操作延时甚至失败。传统的单节点数据库或ORACLE RAC集群已无法应对。根据目前成熟的业界解决方案,采用读写分离的方式,可以有效解决这个问题。展开更多
为了解决传统RAID5机制小写性能低下问题,设计了一种高性能的冗余管理机制RMR(RedundancyManagement for RAID5).RMR通过异步冗余计算方法APC(Asynchronous Parity Calculating),对传统RAID5写更新机制的关键技术进行了优化,将集中计算...为了解决传统RAID5机制小写性能低下问题,设计了一种高性能的冗余管理机制RMR(RedundancyManagement for RAID5).RMR通过异步冗余计算方法APC(Asynchronous Parity Calculating),对传统RAID5写更新机制的关键技术进行了优化,将集中计算校验块的同步操作分解为同步的并行镜像写操作和异步冗余计算操作.该操作分解了数据与其校验数据更新的紧耦合特性,提高了写操作并发度;通过合并多个版本镜像块写操作减少异或计算操作的次数.测试表明,通过RMR机制,可将小写性能大幅提高,峰值可达4倍以上.展开更多
文摘基于DRAM的内存子系统在容量不断增大的过程中消耗了40%的能量。相变随机访问存储器PRAM(phase-change random access memory)作为潜在的替代品可以解决内存容量和能耗的问题。然而,PRAM存在写操作寿命有限和带宽较低等问题。为此提出了的Shift-Min-Write机制,通过减少写操作流量达到延长写操作寿命和增加写带宽的目的。实验结果证明:与传统方法相比,新方法可以增加写带宽和写寿命1倍以上,并减少大约60%的写操作,而且不会随字宽增大而有明显的退化。
基金the National Natural Science Foundation of China under Grant No.62072419the Huawei-USTC Joint Innovation Project on Fundamental System Software。
文摘The recently proposed learned index has higher query performance and space efficiency than the conventional B+-tree.However,the original learned index has the problems of insertion failure and unbounded query complexity,meaning that it supports neither insertions nor bounded query complexity.Some variants of the learned index use an out-of-place strategy and a bottom-up build strategy to accelerate insertions and support bounded query complexity,but introduce additional query costs and frequent node splitting operations.Moreover,none of the existing learned indices are cache-friendly.In this paper,aiming to not only support efficient queries and insertions but also offer bounded query complexity,we propose a new learned index called COLIN(Cache-cOnscious Learned INdex).Unlike previous solutions using an out-of-place strategy,COLIN adopts an in-place approach to support insertions and reserves some empty slots in a node to optimize the node’s data placement.In particular,through model-based data placement and cache-conscious data layout,COLIN decouples the local-search boundary from the maximum error of the model.The experimental results on five workloads and three datasets show that COLIN achieves the best read/write performance among all compared indices and outperforms the second best index by 18.4%,6.2%,and 32.9%on the three datasets,respectively.
基金the National Key Research and Development Program of China(2018YFB1004401)the National Natural Science Foundation of China for Young Scientists(Grant No.61502392)the General Program of the National Natural Science Foundation of China(61472323).
文摘The emergence of non-volatile memory(NVM)has introduced new opportunities for performance optimizations in existing storage systems.To better utilize its byte-addressability and near-DRAM performance,NVM can be attached on the memory bus and accessed via load/store memory instructions rather than the conventional block interface.In this scenario,a cache line(usually 64 bytes)becomes the data transfer unit between volatile and non-volatile devices.However,the failure-atomicity of write on NVM is the memory bit width(usually 8 bytes).This mismatch between the data transfer unit and the atomicity unit may introduce write amplification and compromise data consistency of node-based data structures such as B+-trees.In this paper,we propose WOBTree,a Write-Optimized B+-Tree for NVM to address the mismatch problem without expensive logging.WOBTree minimizes the update granularity from a tree node to a much smaller subnode and carefully arranges the write operations in it to ensure crash consistency and reduce write amplification.Experimental results show that compared with previous persistent B+-tree solutions,WOBTree reduces the write amplification by up to 86× and improves write performance by up to 61× while maintaining similar search performance.
文摘文章研究了使用Oracle Active Data Guard实现PMS2.0数据库读写分离。生产管理系统PMS是电力信息系统中重要的核心业务系统,随着数据量不断快速增长,数据库的I/O吞吐量以及资源的耗用愈发凸显性能瓶颈,造成业务用户并发操作延时甚至失败。传统的单节点数据库或ORACLE RAC集群已无法应对。根据目前成熟的业界解决方案,采用读写分离的方式,可以有效解决这个问题。
文摘为了解决传统RAID5机制小写性能低下问题,设计了一种高性能的冗余管理机制RMR(RedundancyManagement for RAID5).RMR通过异步冗余计算方法APC(Asynchronous Parity Calculating),对传统RAID5写更新机制的关键技术进行了优化,将集中计算校验块的同步操作分解为同步的并行镜像写操作和异步冗余计算操作.该操作分解了数据与其校验数据更新的紧耦合特性,提高了写操作并发度;通过合并多个版本镜像块写操作减少异或计算操作的次数.测试表明,通过RMR机制,可将小写性能大幅提高,峰值可达4倍以上.
