Extending the Limits of Large-Scale Shared Memory Multiprocessors

本研究的目的是通过使用程序员定义的轻量级事务作为表达并行性、描述通信、内存一致性推理、提供故障恢复和允许性能优化的单一抽象，从而大大提高程序员为千万亿次规模的系统编写应用程序的生产力。事务作为设计和编程并行系统的核心抽象，导致了共享内存编程和内存一致性模型，称为事务一致性和一致性（TCC）。事务通过提供一种不用线程、锁和信号量编写正确的共享内存程序的方法，简化了并行编程。TCC系统提供高性能通信和同步，支持硬件机制，可以保持基于程序员定义的事务的内存一致性和一致性。为了实现研究目标，本研究计划将重点关注五个活动。首先，研究人员将开发新的抽象，使用事务提供共享内存编程模型，使其更容易分析和优化应用程序性能。其次，研究人员将开发性能监控系统，利用事务来检测性能瓶颈，并向程序员提供直观的反馈。第三，研究人员将使用基于事务的编程模型来实现基于编译器的静态和动态反馈导向优化，自动检测和消除性能瓶颈，并将事务一致性的可扩展性扩展到105个处理器。第四，研究人员将使用事务来优化并行存储I/O的性能。最后，研究人员将开发模拟和仿真技术，使我们能够在支持轻量级事务的千万亿次级系统可用之前进行实验。更广泛的影响这项研究的广泛影响是使用基于事务的并行编程来教育和启用新的并行软件开发人员，他们可以使用与今天编写顺序软件相同的工具来实现并行软件。实现并行软件开发对于将计算性能从桌面应用程序提升到大规模科学和商业应用程序至关重要。虽然并行处理在大型机器上已经必不可少了一段时间，但英特尔、AMD和IBM最近的声明表明，它很快也将成为桌面应用程序的关键。为了让学生、其他研究人员和业界了解基于事务的并行编程的好处，我们将在并行编程课程中纳入事务编程的概念，并使基于事务的应用程序可用于更广泛的科学界。研究人员希望发布一套优化的基于事务的应用程序以及模拟技术，这将有助于鼓励其他研究人员试验和探索事务的好处。为了进一步推广基于事务的并行编程的使用，我们将在一个主要的科学计算会议上组织一个教程或研讨会，其中将涵盖使用事务编程的原则和经验。

The objective of this research is to substantially improve the productivity of programmers writingapplications for petaflop-scale systems by using programmer defined light-weight transactions as thesingle abstraction for expressing parallelism, delineating communication, reasoning about memoryconsistency, providing failure recovery, and allowing performance optimization. Transactions as thecentral abstraction for designing and programming parallel systems leads to a shared memoryprogramming and memory coherence model called Transaction Coherence and Consistency (TCC).Transactions simplify parallel programming by providing a way of writing correct shared-memoryprograms without threads, locks and semaphores. TCC systems provide high performance communicationand synchronization with support for hardware mechanisms that can keep memory coherent andconsistent based on programmer-defined transactions.To achieve the research objective, this research program will focus on five activities. First, the researcherswill develop new abstractions that use transactions to provide a shared memory programming model thatmakes it much easier to analyze and optimize application performance. Second, the researchers willdevelop performance monitoring systems that make use of transactions to detect performance bottlenecksand to provide intuitive feedback to programmers. Third, the researchers will use the transaction basedprogramming model to implement compiler-based static and dynamic feedback-directed optimizationsthat automatically detect and eliminate performance bottlenecks and extend the scalability of transactioncoherency to 105 processors. Fourth, the researchers will use transactions to optimize the performance ofparallel storage I/O. Finally, the researchers will develop simulation and emulation technology that willenable us to experiment with petaflop-scale systems that support light-weight transactions before they areavailable.Broader ImpactsThe broad impact of this research is to use transaction-based parallel programming to educate and enablea new class of parallel software developers who can implement parallel software with the same facilitythat sequential software is written today. Enabling parallel software development will be critical toadvancing computing performance from desktop applications to large-scale scientific and commercialapplications. While parallel processing has been essential for large-scale machines for a while, recentannouncements by Intel, AMD and IBM demonstrate that it will soon be critical for desktop applicationsas well. To educate students, other researchers, and industry about the benefits of transaction-basedparallel programming, we will incorporate transactional programming concepts in the parallelprogramming curriculum and make transaction-based applications available to the wider scientificcommunity. The researchers expect that releasing a suite of optimized transaction-based applicationsalong with simulation technology will be instrumental in encouraging other researchers to experimentwith and explore the benefits of transactions. To further promote the use of transaction-based parallelprogramming we will organize a tutorial or workshop at a major scientific computing conference that willcover the principles and experience of programming with transactions.