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

[71256] 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，这些服务器构成了互联网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，迄今为止仅限于处理器核心，处理器，内存以及它们之间的相互作用。工作的一个驱动焦点是多播窥探，这是一种新的缓存一致性方法，它使用预测来增加经典对称多处理器的有效带宽，并减少传统基于目录的系统的延迟。多播窥探使用预测来“猜测”哪个处理器有一个块的副本，并向这些处理器发送多播地址事务。一种新的网络组织将同时组播与不相交的组播集结合在一起，同时仍能提供顺序保证。一个简化的目录验证预测并在不正确时采取纠正措施。改进组播窥探在软硬件掩码预测、网络实现、正向进展、高可用性等方面提出了研究挑战，并为协议和网络行为提供了理论基础。预测和推测在多处理器系统中的应用也暴露了适用于更普遍的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。仅硬件，以及硬件/软件解决方案策略正在探索中。研究计划包括设计（改进现有想法和开发新想法）、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（将技术转移到工业）和基础设施开发（工具适应和构建）。

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).