Experimental Partnerships: Multifacet: Exploiting Prediction and Speculation in Multiprocessor Memory Systems

9971256 Hill，Mark D.Wood，David A.威斯康星大学-麦迪逊分校的实验伙伴关系：多方面：利用多处理器内存系统中的预测和推测这项研究的目标是提高多处理器服务器的性能，这些服务器构成互联网Web服务器、数据库和其他要求苛刻的应用程序的计算基础设施。它广泛地研究了利用预测和推测，到目前为止仅限于处理器核心、处理器、内存以及它们之间的交互。这项工作的一个主要焦点是多播侦听，这是一种新的高速缓存一致性方法，它使用预测来增加传统对称多处理器的有效带宽，并减少传统的基于目录的系统的延迟。组播侦听使用预测来“猜测”哪些处理器拥有到这些处理器的块和组播地址事务的副本。一种新颖的网络组织将同时多播组合成不相交的多播集，同时仍提供排序保证。简化的目录会验证预测，并在不正确时采取纠正措施。改进的多播侦听技术在硬件和软件掩码预测、网络实现、前向进度、高可用性以及协议和网络行为的理论基础等方面提出了研究挑战。预测和推测在多处理器系统中的应用也暴露了更广泛地适用于多处理器的研究机会，包括升级推测、虚假共享推测、锁叠加和推测实现问题。仅限于硬件，以及硬件/软件解决方案战略正在探索中。研究计划包括设计(对现有想法的提炼和新想法的开发)、评估(修剪设计空间并与现有替代方案进行比较)、验证(确保设计工作，包括Lamport逻辑时钟的新应用)、演示(将技术转移到行业)和基础设施开发(工具调整和建设)。

9971256Hill, Mark D.Wood, David A.University of Wisconsin - MadisonCISE Experimental Partnerships: Multifacet: Exploiting Prediction and Speculation in Multiprocessor Memory SystemsThe goal of this research is to improve the performance of multiprocessor servers that form the computational infrastructure for internet web servers, databases, and other demanding applications. It broadly examines exploiting prediction and speculation, heretofore limited to processor cores, in processors, memory, and the interactions between them. A driving focus of the work is multicast snooping, a new cache coherence approach that uses prediction to both increase effective bandwidth over a classical symmetric multiprocessor and reduce latency over a traditional directory-based system. Multicast snooping uses prediction to "guess" which processors have copies of a block and multicast address transactionsto those processors. A novel network organization combines simultaneous multicasts to disjoint multicast sets while still providing ordering guarantees. A simplified directory verifies the prediction and takescorrective action when incorrect. Refining multicast snooping provides research challenges in areas such as hardware and software mask prediction, network implementation, forward progress, high availability, and atheoretical foundation for protocol and network behaviors.The application of prediction and speculation to multiprocessor systems also exposes research opportunities applicable to multiprocessors more generally, including upgrade speculation, false sharing speculation, locksuperposition, and speculation implementation issues. Hardware only, as well as hardware/software solutions strategies are being explored. The research plan encompasses design (refinement of existing ideas and development of new ones), evaluation (pruning the design space and comparing with existing alternatives), validation (ensuring designs work, including a new application of Lamport's logical clocks), demonstration (transferring technology to industry), and infrastructure development (tool adaptation and construction).