SI2-SSE: PAPI Unifying Layer for Software-Defined Events (PULSE)

物理、化学、气候科学和先进材料设计等领先的科学领域利用高性能计算（HPC）来理解和解决前所未有的复杂问题。克服这些挑战需要能够执行先进的科学和工程模拟，并分析这些计算机模型涉及的极端数据量。但是，这些问题的规模不断扩大也意味着解决这些问题所需的软件系统的复杂性正在上升，这一事实为需要HPC来实现其目标的科学应用社区提出了新的挑战。特别是，对于希望了解其应用程序性能特征的HPC应用程序开发人员，他们以前能够监控其与底层硬件的交互方式，但他们无法获得访问其应用程序所依赖的复杂软件堆栈行为的标准化方法。PULSE项目将填补这一主要软件基础设施空白。它提供了一个集成的解决方案，使复杂软件栈的不同层能够相互通信，并提供有关其内部行为的信息。因此，PULSE使未来的科学应用能够利用不断增加的计算能力，尽管未来硬件和软件技术的复杂性预计会增加。通过提供开发人员所需的基础设施，以实现对整个程序行为的分析理解，它将大大提高计算科学家对各种现代软件系统如何相互作用以及底层硬件技术的洞察力。
十多年来，性能应用程序编程接口（PAPI）提供的抽象和标准化层在支持应用程序分析方面发挥了关键作用。它使具有性能意识的开发人员能够通过使用少量跨不同硬件基板互操作的PAPI函数来简单地检测他们的代码来了解他们的应用程序。与此同时，PAPI提供的抽象层使复杂的分析工具包能够专注于以对最终用户有用的方式组合，组织和可视化信息，而不是为市场上的每个新平台重新实现硬件访问层。但是，PAPI提供的这个抽象层仅限于分析硬件生成的信息。必须通过低级二进制插装或通过自定义API来获取关于正在分析的应用程序下的软件堆栈的行为的信息。现在，通过这个PULSE项目，用于分析软件事件的抽象和统一层已经出现。PULSE将扩展PAPI为硬件事件提供的抽象和统一层，使其也包含软件事件。一方面，它将提供一个标准的、定义良好的和有良好文档记录的API，高级剖析软件可以利用该API来获取并向应用程序开发人员呈现关于其应用程序所使用的库的性能信息。另一方面，它将提供标准API，库和运行时编写者可以利用这些API向更高的软件层传递有关其软件行为的信息。预计该项目将对整个程序分析和理解的最新技术水平产生直接影响。PULSE的成功将极大地提高计算科学家和工程师对现代软件的不同模块彼此交互以及与底层硬件交互方式的洞察力。如在PULSE下提议的那样，扩大PAPI的适用范围，预计将大大增加PAPI在这一领域的影响。

Leading scientific domains, such as physics, chemistry, climate science, and advanced materials design, utilize high-performance computing (HPC) to understand and solve problems of unprecedented complexity. Overcoming such challenges requires the ability to perform advanced scientific and engineering simulations, and to analyze the extreme amount of data these computer models involve. But the ever increasing scale of these problems also means that the complexity of software systems needed to address them is rising, and this fact raises new challenges for the scientific application communities that require HPC in order to achieve their goals. In particular, HPC application developers who want to understand the performance characteristics of their application had previously been able to monitor the way it interacted with the underlying hardware, but they had no access to a standardized way of accessing the behavior of the complex software stack that their application depends on. The PULSE project will fill this major software infrastructure gap. It offers an integrated solution that enables different layers of a complex software stack to communicate with one another and provide information about their internal behavior. Thus, PULSE makes it possible for the scientific applications of the future to harness ever increasing amounts of computing power, despite anticipated increases in the complexity of both future hardware and software technologies. By providing the infrastructure that developers need in order to achieve an analytical understanding of the behavior of whole programs, it will substantially improve the insight computational scientists have into how various modern software systems interact with one another and the underlying hardware technologies. 
The abstraction and standardization layer provided by the Performance Application Programming Interface (PAPI) has played a critical role in enabling application profiling for over a decade. It has enabled performance conscious developers to gain insights about their application by simply instrumenting their code using a handful of PAPI functions that interoperate across different hardware substrates. At the same time, the abstraction layer offered by PAPI has enabled sophisticated profiling toolkits to focus on combining, organizing and visualizing information in a way that is useful to the end user, instead of re-implementing the hardware access layer for every new platform that comes to market. However, this abstraction layer that PAPI offers has been limited to profiling information generated by hardware. Information regarding the behavior of the software stack underneath the application that is being profiled has to be acquired either through low level binary instrumentation, or through custom APIs. Now, through this PULSE project, abstraction and unification layer for profiling software events has emerged. PULSE will extend the abstraction and unification layer that PAPI has provided to hardware events to also encompass software events. On one end, it will provide a standard, well defined and well documented API that high level profiling software can utilize to acquire and present to application developers performance information about the libraries used by their application. On the other end, it will provide standard APIs that library and runtime writers can utilize to communicate to higher software layers information about the behavior of their software. The project is expected to have a direct influence on the state of the art in whole program profiling and understanding. The success of PULSE will substantially improve the insight of computational scientists and engineers into the way that different modules of modern software interact with one another and the underlying hardware. Broadening the applicability of PAPI, as proposed under PULSE, is expected to dramatically increase PAPI's impact in this area.