基于弱隔离性的事务内存冲突分析

发布时间：2019-01-26 17:33

【摘要】：事务内存是一种扩展性好、易于编程的并行编程模型,其核心技术在于事务冲突的检测和处理.已有研究工作主要关注于冲突检测机制,但缺少对如何减少事务冲突的深入研究.分析表明,冲突概率的增长会严重降低事务内存系统的性能,并且随着处理器核数目的增长,这一问题会变得更加严重.研究发现,事务系统中弱隔离性模型的使用可以系统性地减少事务执行中的冲突,从而提升程序执行效率.基于该研究,提出了弱隔离性冲突检测方法(weak isolation conflict detection,WICD),并在SESC事件驱动模拟器上对WICD进行实现和评估,结果表明,与传统的严格隔离性模型相比,弱隔离性模型下最高可以减少35.7%的事务冲突,提升系统性能最大为31.0%.基于WICD的方法,通过对部分冲突进行立即检测,进而提出了一种改进的弱隔离性冲突检测方法(enhanced WICD,EWICD).实验表明,EWICD对于事务冲突的减少比率和WICD近似,最高达到33.8%,对系统性能的提升优于WICD,最大达到36.8%.
[Abstract]:Transaction memory is a kind of parallel programming model with good expansibility and easy programming. The core technology of transaction memory is the detection and processing of transaction conflicts. The existing researches mainly focus on conflict detection mechanism, but lack of in-depth research on how to reduce transaction conflicts. The analysis shows that the increase of collision probability will seriously reduce the performance of the transaction memory system, and the problem will become more serious as the number of processor cores increases. It is found that the use of weak isolation model in transaction systems can systematically reduce the conflicts in transaction execution and improve the efficiency of program execution. Based on this research, a weak isolation conflict detection method (weak isolation conflict detection,WICD) is proposed, and the WICD is implemented and evaluated on the SESC event-driven simulator. The results show that compared with the traditional strict isolation model, the proposed method is more efficient than the traditional one. Under the weak isolation model, the transaction conflicts can be reduced by 35.7%, and the system performance can be improved by 31.0%. Based on the method of WICD, an improved weak isolation conflict detection method (enhanced WICD,EWICD) is proposed by detecting some conflicts immediately. The experimental results show that the ratio of EWICD to transaction conflict reduction is approximately 33.8 as compared with that of WICD, and the system performance is improved better than that of WICD, and the maximum is 36.8.
【作者单位】：体系结构国家重点实验室(中国科学院计算技术研究所);中国科学院大学;龙芯中科技术有限公司;
【基金】：国家科技重大专项基金项目(2009ZX01028-002-003,2009ZX01029-001-003,2010ZX01036-001-002,2012ZX01029-001-002-002) 国家自然科学基金项目(61221062,61100163,61133004,61173001,61232009,61222204) 国家“八六三”高技术研究发展计划基金项目(2012AA010901,2012AA011002,2012AA012202,2013AA014301)
【分类号】：TP333

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