Energy-Aware Coarse-Grained Reconfigurable Architectures using Dynamically Reconfigurable Isolation Cells

Syed M. A. H. Jafri1,  Ozan Zeki Bag1,  Ahmed Hemani1,  Nasim Farahini1,  Kolin Paul1,  Juha Plosila2,  Hannu Tenhunen1
1Royal Institute of Technology (KTH) Sweden, 2University of Turku (UTU) Finland


This paper presents a self adaptive architecture to enhance the energy efficiency of coarse-grained reconfigurable architectures (CGRAs). Today, platforms host multiple applications, with arbitrary inter-application communication and concurrency patterns. Each application itself can have multiple versions (implementations with different degree of parallelism) and the optimal version can only be determined at runtime. For such scenarios, traditional worst case designs and compile time mapping decisions are neither optimal nor desirable. Existing solutions to this problem employ costly dedicated hardware to configure the operating point at runtime (using DVFS). As an alternative to dedicated hardware, we propose exploiting the reconfiguration features of modern CGRAs. Our solution relies on dynamically reconfigurable isolation cells (DRICs) and autonomous parallelism, voltage, and frequency selection algorithm (APVFS). The DRICs reduce the overheads of DVFS circuitry by configuring the existing resources as isolation cells. APVFS ensures high efficiency by dynamically selecting the parallelism, voltage and frequency trio, which consumes minimum power to meet the deadlines on available resources. Simulation results using representative applications (Matrix multiplication, FIR, and FFT) showed up to 23 % and 51 % reduction in power and energy, respectively, compared to traditional DVFS designs. Synthesis results have confirmed significant reduction in overheads compared to state of the art DVFS methods.