CSR: Medium: Collaborative Research: Scaling the Implicitly Parallel Programming Model with Lifelong Thread Extraction and Dynamic Adaptation

面对物理和微体系结构的限制，微处理器行业已经转向多核设计，以利用不断增加的晶体管数量。遗憾的是，提供多核并不能转化为大多数应用程序的性能。这个项目不是把所有的负担都推给程序员，而是提倡使用隐式并行编程模型来消除显式并行编程的繁琐和容易出错的过程。隐式并行编程利用顺序语言来缩短开发和调试周期，并依赖自动工具(静态编译器和运行时系统)来识别并行性并根据目标平台对其进行定制。隐式并行性可以使用以下方法系统地提取：(1)解耦软件流水线，这是一种在许多顺序应用程序中发现的提取流水线并行性的技术；(2)低频和高置信度推测，以克服内存依赖分析的限制；(3)用于并行化的全程序范围，以消除分析边界；(4)对顺序编程模型的简单扩展，赋予程序员细化程序含义的能力；(5)动态适应，以确保在变化的环境中保持效率。该项目正在开发一套技术，以实现一个隐式并行编程系统，具有可伸缩的、终身线程提取和动态适应。在更广泛的层面上，隐式并行编程方法将解放程序员考虑他们试图解决的问题，而不是强迫他们克服处理器行业无法继续扩展性能的问题。这种方法将使计算机保持可访问性，帮助计算对其他领域产生同样日益积极的影响。

The microprocessor industry has moved toward multicore designs to leverage increasing transistor counts in the face of physical and micro-architectural limitations. Unfortunately, providing multiple cores does not translate into performance for most applications. Rather than pushing all the burden onto programmers, this project advocates the use of the implicitly parallel programming model to eliminate the laborious and error-prone process of explicit parallel programming. Implicit parallel programming leverages sequential languages to facilitate shorter development and debug cycles, and relies on automatic tools, both static compilers and run-time systems, to identify parallelism and customize it to the target platform. Implicit parallelism can be systematically extracted using: (1) decoupled softwarepipelining, a technique to extract the pipeline parallelism found in many sequential applications; (2) low-frequency and high-confidence speculation to overcome limitations of memory dependence analysis; (3) whole-program scope for parallelization to eliminate analysis boundaries; (4) simple extensions to the sequential programming model that give the programmer the power to refine the meaning of a program; (5) dynamic adaptation to ensure efficiency is maintained across changing environments. This project is developing the set of technologies to realize an implicitly parallel programming system with scalable, lifelong thread extraction and dynamic adaptation. At the broader level, the implicitly parallel programming approach will free programmers to consider the problems they are trying to solve, rather than forcing them to overcome the processor industry's failure to continue to scale performance. This approach will keep computers accessible, helping computing to have the same increasingly positive impact on other fields.