Weakly Consistent Memories

共享内存是一个非常重要的并行抽象 系统. 在分布式环境中提供共享内存抽象 硬件可能同样重要，因为它允许进程 统一访问本地和远程信息。 然而，实施 分布式环境中的一致共享内存不仅 成本高，但也存在延迟和规模的根本问题。 的 最近的研究结果表明， 内存一致性可以降低一致性维护的成本 同时保持可行的编程模式。 该项目将 研究从理论和实践中产生的问题， 弱一致性记忆的研究 理论工作将 包括对现有和新存储器正式表征 以及对正确执行的程序的属性的调查 当记忆一致性减弱时。 这项研究成果 将增强我们对弱记忆的基本理解。 到 证明了弱记忆可以很容易地被编程， 提高性能，实际工作将调查编程 和弱一致性记忆的实现。 的程序员 弱一致性存储器可以“直接”为 每周一致的模型，或为传统的 一致的存储器可以被转换为在 弱一致记忆 该项目将确定应用 适合弱记忆的领域，开发简化 这些存储器的编程，并开发高效的分布式 弱一致性记忆的实现。 由于应用程序 在一致的和弱的记忆中，总体而言， 性能既取决于算法的效率， 应用和表现的基础弱记忆 实施. 因此，这项工作包括实验研究， 使用测量方法研究原型系统的整体性能 例如执行加速和消息开销。 全面 弱一致性记忆的理论与实践研究 将产生适用于两个分布式系统的实质性益处 大规模多处理器。

Shared memory is a fundamentally important abstraction in parallel systems. Providing a shared memory abstraction across distributed hardware may prove equally important because it allows processes to access local and remote information uniformly. However, implementing consistent shared memory in a distributed environment is not only costly but also has fundamental problems of latency and scale. The results of recent research suggest that the principled weakening of memory consistency can reduce the cost of consistency maintenance while maintaining a viable model for programming. This project will investigate both theoretical and practical issues arising from the study of weakly consistent memories. The theoretical work will include a formal characterization of both existing and new memories and an investigation of properties of programs that execute correctly when memory consistency is weakened. The results of this research will enhance our fundamental understanding of weak memories. To demonstrate that weak memories can be easily programmed and lead to improved performance, the practical work will investigate programming and implementation of weakly consistent memories. Programmers of weakly consistent memories may write programs "directly" for the weekly consistent model, or programs written for traditional consistent memory may be transformed to run more efficiently on a weakly consistent memory. The project will identify application domains suitable for weak memories, develop idioms that simplify the programming of these memories, and develop efficient distributed implementations of weakly consistent memories. Since an application may be programmed differently on consistent and weak memories, overall performance depends both on the algorithmic efficiency of the application and the performance of the underlying weak memory implementation. Therefore, the work includes experimental research to study the overall performance of a prototype system using measures such as execution speedup and message overhead. Comprehensive investigation of the theory and practice of weakly consistent memories will yield substantial benefits applicable to both distributed systems and large scale multiprocessors.