III: Small: Avoiding Contention on Multicore Machines

III：小：避免多核机器上的争用

• 批准号: 0915956
• 负责人: Kenneth Ross
• 金额: $ 50万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0915956&HistoricalAwards=false
• 关键词: III; Small; Avoiding; Contention; Multicore

To take full advantage of the parallelism offered by a multicoremachine, one must write parallel code. Writing parallel code isdifficult. Even when one writes correct code, there are numerousperformance pitfalls. For example, an unrecognized data hotspot couldmean that all threads effectively serialize their access to thehotspot, and throughput is dramatically reduced.This project aims to provide a generic framework for performingcertain kinds of concurrent operations in parallel. Infrastructure isprovided to perform those operations in a scalable way over theavailable threads in a multicore machine, automatically responding tohotspots and other performance hazards. The goal is not to squeezethe last drop of performance out of a particular platform. Rather,with the planned system a programmer can, without detailed knowledgeof concurrent and parallel programming, develop code that efficientlyutilizes a multicore machine.The project involves the development of algorithms and data structuresdesigned for the efficient parallel execution of generic codefragments. The primary focus is on data intensive operations as wouldtypically be found in an in-memory database engine. Critical researchquestions include how to design generic multi-threaded operators thatcan be applied to a range of computations, how to avoid cachethrashing, and how to implement the framework in a way that works on avariety of hardware platforms. Performance improvements in throughputof an order of magnitude are expected relative to naive solutions thatsuffer from contention. The project aims to achieve performance closeto that of hand-tailored expert-written parallel code, with far lesscoding effort.This project has immediate applications in both commercial andpublic-domain database systems where performance improvements wouldenhance the experience of database system users, and reduce hardwareand energy requirements for a given level of performance.Programmability improvements would allow programmers without expertisein parallel programming to effectively use multicore machines. Theproject also provides the focus for an advanced-level course ondatabase system implementation for multicore machines. The softwareinfrastructure will be made available for research use by others.

要充分利用多核机器提供的并行性，必须编写并行代码。编写并行代码很困难。即使编写了正确的代码，也存在许多性能陷阱。例如，一个未被识别的数据热点可能意味着所有线程有效地串行化它们对该热点的访问，并且吞吐量显著降低。该项目旨在为并行执行某些类型的并发操作提供一个通用框架。提供了基础设施，以便在多核机器中的可用线程上以可扩展的方式执行这些操作，自动响应热点和其他性能风险。我们的目标不是把某一特定平台的性能挤出最后一滴。相反，有了计划中的系统，程序员可以在没有详细的并发和并行编程知识的情况下，开发高效地利用多核机器的代码。该项目涉及为高效地并行执行通用代码片段而设计的算法和数据结构的开发。主要的关注点是数据密集型操作，通常可以在内存中的数据库引擎中找到。关键的研究问题包括如何设计可应用于各种计算的通用多线程操作符，如何避免缓存抖动，以及如何以一种在各种硬件平台上工作的方式实现该框架。与受到争用的幼稚解决方案相比，吞吐量方面的性能有望提高一个数量级。该项目的目标是以更少的编码工作量实现接近手工定制的专家编写的并行代码的性能。该项目在商业和公共领域的数据库系统中立即得到应用，在这些系统中，性能的改进将增强数据库系统用户的体验，并降低对给定性能水平的硬件和能源需求。可编程性的改进将允许没有并行编程经验的程序员有效地使用多核机器。该项目还提供了一门关于多核机器数据库系统实现的高级课程的重点。软件基础设施将提供给其他人进行研究使用。