Architectural Design Exploration for Real-Time Embedded Systems

硬件和软件设计的进步使系统设计者能够开发大型、复杂的嵌入式系统。这样的系统可能包含运行在通用或专用处理器、高速存储器系统和特定于应用程序的硬件设备上的软件程序的混合物。设计这些系统的关键任务之一是找到“最佳”的系统架构，包括确定硬件和软件组件之间的“正确”分区以及选择“正确”的硬件组件。这个项目的重点是开发一种可行的方法以及一组工具，以帮助系统设计者完成这个架构设计探索任务。本研究在系统层面进行设计探索。在这个级别上，系统被指定为任务图的集合，实现通过硬件组件的互连和对硬件组件的进程分配来描述。尽管该问题与硬件综合问题有一些相似之处，但要使该方法有效，还需要解决许多不同的问题。其中一个问题是确定和估计勘探过程中要包括的适当参数，以便能够充分预测系统定时性能。该项目强调具有实时约束的嵌入式系统的设计探索。这种系统可以在许多应用中找到，例如飞机的导航和着陆控制，网络和通信。将设计对指导设计探索有用的属性，以便根据系统时序规范有效地分析大量实现的时序行为，从而允许探索广泛的设计选项。其他问题包括灵敏度分析和组件重用也将得到解决。为了正确处理包括功能属性和非功能属性在内的相互冲突的性能需求，将采用基于效用理论的不精确价值函数的方法。进一步将设计探索问题表述为多属性优化问题。为了解决优化问题的指数性质，将研究进化计算领域的技术。

Advances in both hardware and software design have enabled system designers to develop large, complex embedded systems. Such systems may contain a mixture of software programs running on general purpose or special-purpose processors, high-speed memory systems, and application specific hardware devices. One of the key tasks in designing these systems is to find a "best" system architecture including determining the "right" partition between hardware and software components and selecting the "right" hardware components. The focus of this project is to develop a viable methodology as well as a set of tools to assist system designers in this architectural design exploration task. The research proposed performs design exploration at the system level. At this level, a system is specified as a collection of task graphs and an implementation is described by an interconnection of hardware components and an assignment of processes to the hardware components. Though the problem shares some similarities with the hardware synthesis problem, many different issues need to be addressed in order for this approach to be effective. One of the issues is identifying and estimating appropriate parameters to be included in the exploration process such that system timing performance can be adequately predicted. The project emphasizes design exploration for embedded systems with real-time constraints. Such systems can be found in many applications, such as navigation and landing control of aircraft, networks and communications. Attributes that are useful for guiding design exploration will be devised so as to efficiently analyze the timing behavior of a large number of implementations with respect to the system timing specifications and hence permit exploration of a wide range of design options. Other issues including sensitivity analysis and component reuse will also be addressed. To properly handle conflicting performance requirements including both functional and non-functional attributes, an approach based on imprecise value functions from utility theory will be pursued. Furthermore, the design exploration problem is formulated as a multi-attribute optimization problem. Techniques from the evolutionary computation field will be investigated in order to tackle the exponential nature of the optimization problem.