CPA-CPL-T: Collaborative Research: REEact: A Robust Execution Environment for Fragile Multicore Systems

随着多核架构的出现，有望在单个芯片中集成巨大的计算能力，从而在包括手持计算机和台式机在内的所有类型的平台上实现并行计算。为应用程序提供适当的软件支持对于充分利用此架构的真正威力至关重要。构成重大障碍的多核的固有特征是运行时变化：可靠性、能量/热行为和过程变化将在设计相同的多核组件之间变化，从而对应用程序功耗和性能产生负面影响。运行时变化已被认为是关键问题之一，如果解决不好，可能会阻碍电路的进一步扩展。这项研究项目正在开发一个高级执行系统，称为健壮执行环境(REEACT)，它动态地调解、控制和调整应用程序的执行，以适应源于运行时变化的运行时资源环境。它在调整硬件资源和应用程序软件代码方面采用了一种技术组合，以克服运行时变化的影响。在硬件层面，它对资源进行适配，例如设置多核上节点的速度/电压。在软件级别，REEACT动态优化代码，同时考虑到运行时变化导致的性能和功耗。它在确定在运行应用程序时使用哪些资源方面得到操作系统的帮助。REEACT向操作系统通知它动态发现的有关延迟、电源和应用程序行为的信息。REEACT构建为多层分层运行时系统，该系统与并行应用程序、操作系统和底层多核体系结构交互，以确保实现最高性能。

With the emergence of the multicore architecture comes the promise of integrating enormous computing power in a single chip, thereby enabling parallel computing in all types of platforms including handheld computers and desktop machines. Providing proper software support for applications is critical to harness the true power of this architecture. An inherent characteristic of multicores that presents a significant obstacle is runtime variation: reliability, energy/thermal behavior and process variation will vary across identically designed components of a multicore, producing a negative impact on application power consumption and performance. Runtime variation has been identified as one of the key problems that could block further scaling of circuits if not properly addressed. This research project is developing an advanced execution system, called a Robust Execution Environment (REEact), that dynamically mediates, controls and adapts an application's execution to the runtime resource landscape originating from runtime variations. It employs a combination of techniques in adapting both the hardware resources and the application software code to overcome the impact of runtime variations. At the hardware level, it adapts the resources, such as setting the speed/voltage of a node on the multicore. At the software level, REEact dynamically optimizes code, taking into account performance and power consumption due to runtime variations. It elicits the help of the OS in determining what resources to use in running the application. REEact informs the OS about information it dynamically discovers about latency, power, and application behavior. REEact is built as multi-layer hierarchical runtime system that interacts with the parallel application, the OS, and the underlying multicore architecture to ensure that maximum performance is achieved.