P.Y.K. Cheung et al. (Eds.): FPL 2003, LNCS 2778, pp. 585–594, 2003.  Springer-Verlag Berlin Heidelberg 2003 Run-Time Minimization of Reconfiguration Overhead in Dynamically Reconfigurable Systems Javier Resano 1 , Daniel Mozos 1 , Diederik Verkest 2,3,4 , Serge Vernalde 2 , and Francky Catthoor 2,4 1 Dept. Arquitectura de Computadores, Universidad Complutense de Madrid, Spain. javier1@fdi.ucm.es, mozos@dacya.ucm.es 2 IMEC vzw, Kapeldreef 75, 3001, Leuven, Belgium {Verkest, Vernalde, Catthoor}@imec.be 3 Professor at Vrije Universiteit Brussel, Belgium 4 Professor at Katholieke Universiteit Leuven., Belgium. Abstract. Dynamically Reconfigurable Hardware (DRHW) can take advantage of its reconfiguration capability to adapt at run-time its performance and its en- ergy consumption. However, due to the lack of programming support for dy- namic task placement on these platforms, little previous work has been pre- sented studying these run-time performance/power trade-offs. To cope with the task placement problem we have adopted an interconnection-network-based DRHW model with specific support for reallocating tasks at run-time. On top of it, we have applied an emerging task concurrency management (TCM) method- ology previously applied to multiprocessor platforms. We have identified that the reconfiguration overhead can drastically affect both the system performance and energy consumption. Hence, we have developed two new modules for the TCM run-time scheduler that minimize these effects. The first module reuses previously loaded configurations, whereas the second minimizes the impact of the reconfiguration latency by applying a configuration prefetching technique. With these techniques reconfiguration overhead is reduced by a factor of 4. 1 Introduction and Related Work Dynamically Reconfigurable Hardware (DRHW), that allows partial reconfiguration at run-time, represents a powerful and flexible way to deal with the dynamism of cur- rent multimedia applications. However, compared with application specific integrated circuits (ASICs), DRHW systems are less power efficient. Since power consumption is one of the most important design concerns, this problem must be addressed at every possible level; thus, we propose to use a task concurrency management (TCM) ap- proach, specially designed to deal with current dynamic multimedia applications, which attempts to reduce the energy consumption at task-level. Other research groups have addressed the power consumption of DRHW, proposing a technique to allocate configurations [1], optimizing the data allocation both for im- proving the execution time and the energy consumption [2], presenting an energy-