CSR---AES: Collaborative Research: Novel Programming Models and Architectures to Simplify Parallel Programming

该项目的重点是多核芯片的编程。该项目的目标是找到一个全面的并行编程环境，可以大大简化多核并行编程。当前的并行编程方法通常对大多数程序员来说过于复杂，或者不能提供足够的性能。需要一个重大突破来简化并行编程，以有效地利用多核硬件。降低并行编程的复杂性并使其广泛使用已经成为系统社区的一个重大研究挑战。它是计算机行业持续创新能力的基础。这个项目的范围是研究两个新的并行编程模型，无论是单独或组合有可能提供显着提高程序员的生产力。Colorama和IPOT是两种新的并行编程模型，它们可能具有简化并行编程的潜力，并被大量程序员所接受。Colorama是一种体系结构支持的数据中心同步（DCS）方法，用于显式并行程序。在DCS中，程序员通过将同步约束与程序数据结构相关联来指定并发控制，通常是在声明或分配同步约束时。这些约束决定了哪些数据结构集在同一数据一致性域中，因此应该保持相互一致。在运行时，当一个线程修改一个数据结构时，系统会自动保护同一域中的所有其他数据结构，使其不被其他线程访问。与使用锁和事务的编程相比，Colorama具有显著的可编程性优势：程序员在本地进行推理，只关注哪些数据结构应该相互一致;系统将自动推断临界区。带有序事务的隐式并行性（IPOT）支持顺序执行线程中的推测线程。其关键思想是允许程序员使用一组简单但非常强大的注释来指定顺序线程内的并行化机会。与显式并行不同，IPOT注释不需要程序员或编译器证明数据或控制依赖的存在。有运行时体系结构支持来检测违规，并挤压和重新启动线程。与传统的TLS不同，该系统可以提取更多的并行性，因为它利用了用户信息。可以单独使用这些模型，或者因为它们是互补的，所以可以组合使用，例如，通过在显式并行代码上使用Colorama，其中每个线程都使用IPOT隐式并行化。这两种模型都需要多核芯片的特殊硬件支持。项目团队的活动涉及多核编程/架构框架的几个层面：1.编程模型--项目团队将研究Colorama、IPOT和统一编程模型（统一是Colorama和IPOT的组合）规范中的设计问题。2.编译--开发编译器技术，提高性能，保证编程模型的正确性。数据库系统--将为这些模型开发库和运行时系统。计算机体系结构--将探讨对这些模型的不同层次的体系结构支持。性能监控和调试工具--将开发一套工具，使程序员能够调试、测试和调优为编程模型编写的程序。应用程序-将开发一套使用编程模型的应用程序。实证生产力研究--一系列实证程序员生产力实验将在伊利诺伊大学的一门课程中进行。这项工作涉及伊利诺伊大学和IBM研究院之间的合作，利用大量现有的IBM赞助的基础设施来发布由项目团队开发的编程环境的完整软件基础设施。

The focus of this project is on the programming of multi-core chips. The goal of the project is to find a comprehensive parallel programming environment that can substantially simplify parallel programming for multi-cores.Current parallel programming approaches are typically too complicated for most programmers or do not deliver adequate performance. A major breakthrough is needed to simplify parallel programming to effectively utilize multi-core hardware. Reducing the complexity of parallel programming and enabling its widespread use has emerged as a Grand Research Challenge for the systems community. It is fundamental to the computer industry''s ability to continue innovating. The scope of this project is to study two novel parallel programming models that either separately or in combination have the potential to provide dramatic improvements in programmer productivity. The two novel parallel programming models that may have the potential to simplify parallel programming and be accepted by large numbers of programmers are Colorama and IPOT.Colorama is an architecture-supported Data Centric Synchronization (DCS) approach, and is used in explicitly parallel programs. In DCS, the programmer specifies concurrency control by associating synchronization constraints with the program data structures, typically when they are declared or allocated. These constraints determine which sets of data structures are in the same data consistency domain and, therefore, should be kept consistent with each other. At run time, when one data structure is being modified by a thread, the system automatically protects all the other data structures in the same domain from access by other threads. Compared to programming with locks and transactions, where the programmer reasons non-locally, Colorama has a significant programmability advantage: the programmer reasons locally, focusing only on what data structures should be consistent with each other; the system will automatically infer the critical sections.Implicit Parallelism with Ordered Transactions (IPOT) supports speculative threads in a sequential thread of execution. The key idea is that the programmer is allowed to specify opportunities for parallelization within the sequential thread using a set of simple yet very powerful annotations. Unlike explicit parallelism, IPOT annotations do not require the programmer or the compiler to prove the absence of data or control dependences. There is runtime architectural support to detect violations, and squash and restart threads. Unlike conventional TLS, the system can extract much more parallelism because it leverages user information. It is possible to use these models separately or, since they are complementary, in combination for example, by using Colorama on explicitly-parallel code where each thread is implicitly parallelized with IPOT. Both models require special hardware support in the multi-core chip.The project teams activities address several layers of multi-core programming/architectural frameworks:1. Programming Models -- The project team will study the design issues in the specification of the Colorama, IPOT, and Unified programming models (Unified is the combination of Colorama and IPOT).2. Compilation -- The team will develop compiler technology to improve the performance and guarantee the correctness of their programming models.3. Runtime System -- Libraries and a runtime system will be developed for these models.4. Computer Architecture -- Different levels of architectural support for these models will be explored.5. Performance Monitoring and Debugging Tools -- A set of tools will be developed that allow programmers to debug, test, and tune programs written for the programming models.6. Applications -- A suite of applications will be developed that use the programming models.7. Empirical Productivity Studies -- A set of empirical programmer productivity experiments will be carried out in a course at the University of Illinois.This work involves a collaboration between the University of Illinois and IBM Research, leveraging a large amount of existing IBM-sponsored infrastructure to release the complete software infrastructure of the programming environment that is developed by the project team.