By means of partial reconfiguration, parts of the hardware can be dynamically exchanged at runtime. This allows that streaming application running in different modes of the systems can share resources. In this paper, we discuss the architectural issues to design such reconfigurable systems. For being able to reduce reconfiguration time, this paper furthermore proposes a novel algorithm to aggregate several streaming applications into a single representation, called merge graph. The paper also proposes an algorithm to place streaming application at runtime which not only considers the placement and communication constraints, but also allows to place merge tasks. In a case study, we implement the proposed algorithm as runtime support on an FPGA-based system on chip. Furthermore, experiments show that reconfiguration time can be considerably reduced by applying our approach. 1. Introduction Embedded systems used to have fixed functionality dedicated to a specific task. A trend of recent years is, however, to build embedded systems which are regarded as “smart.” In this context, the functionality can be adapted, reorganized, and controlled by external requests from human operators or even internal self-managing, self-adapting mechanisms. This means that an embedded system's functionality is not fixed to a single configuration anymore, but several application are running. Still, not all applications are running all the time, but depend on the operational mode of the system. Here, we are speaking of multimode systems, which can, for example, be found in a typical “smart phone” scenario where the operational mode depends, for example, on the radio link quality or the user's input. Other examples are “smart cameras” which have internal adaptation mechanism that switch between appropriate signal processing algorithms. In this paper, we consider multimode streaming applications which can also be found in above-mentioned examples, in the form of signal and image processing flows, but also Data Stream Management Systems, and so forth. In a multimode system, the system resources can be utilized better. This is due to the fact that, during system design, only those applications which run concurrently are considered. This makes it possible to perform resource sharing between processes which run mutually exclusive. When speaking of resource sharing of hardware resources, one precondition is the reconfigurability of the computing platform. In this context, field-programmable gate arrays (FPGAs) offer the capability of partial reconfiguration. This means that hardware
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