片上多核处理器的区域共享的双粒度目录  

A region shared dual-grain directory for chip multi-core processors

作　　者：曾露[1,2,3] 陈新科[1,2,3] 王焕东 

机构地区：[1]计算机体系结构国家重点实验室(中国科学院计算技术研究所)北京100190 [2]中国科学院计算技术研究所北京100190 [3]中国科学院大学北京100049 [4]龙芯中科技术有限公司北京100190

出　　处：《高技术通讯》2015年第7期669-676,共8页Chinese High Technology Letters

基　　金：国家“核高基”科技重大专项课题(2009ZX01028-002-003,2009ZX01029-001-003,2010ZX01036-001-002,2012ZX01029-001-002-002);国家自然科学基金(61221062,61100163,61133004,61173001,61232009,61222204);863计划(2012AA010901,2012AA011002,2012AA012202,2013AA014301)资助项目

摘　　要：研究了双粒度目录(DGD)下片上多核处理器的访存行为以及DGD对不同共享行为的目录开销,以进一步降低DGD结构的面积开销。针对DGD需要为共享缓存区域创建额外的块目录项的问题,提出了创新的区域共享的双粒度目录(RSDGD)结构。该结构可用一个区域共享目录项同时维护最多3个共享者共享同一个缓存区域的一致性,从而能有效减少所需的块目录项数量,降低总的目录开销。实验结果表明,和原有的DGD相比,该结构平均减少了25%的目录空间需求,而仅产生了不到0.6%的性能损失。该结构有效地降低了芯片的面积开销,提高了目录结构的可伸缩性。The memory access behavior of chip multi-core processors under the dual-grain directory （DGD） structure and DGD＇ s directory overhead on sharing behavior were studied to decrease the area overhead of the DGD structure. Aiming at the problem that DGD needs to create additional block directory entries for shared cache regions, an in- novatory region shared DGD, called RSDGD, was proposed. The proposed directory can use one region shared di- rectory entry to track coherence information of a memory region for at most 3 sharers, thus the additional block di- rectory entries are efficiently reduced, and the directory area is saved. The experimental results show that the re- gion shared DGD can save the directory area by 25% in average compared with the former DGD solution, while the caused performance lost is just under 0.6%. This solution is proved to be effective in reducing chip area and in- creasing directory structure＇s elasticity.

关 键 词：双粒度目录(DGD) 片上多核处理器 缓存一致性 区域共享 目录一致性协议 访存优化 

分 类 号：TP332[自动化与计算机技术—计算机系统结构]