Approximate Data Reuse-based Accelerator Design for Embedded Processor

Due to increasing diversity and complexity of applications in embedded systems, accelerator designs trading-off area/energy-efficiency and design-productivity are becoming a further crucial issue. Targeting applications in the category of Recognition, Mining, and Synthesis (RMS), this study proposes a novel accelerator design to achieve a good trade-off in efficiency and design-productivity (or reusability) by introducing a new computing paradigm called "approximate computing" (AC). Leveraging from the facts that frequently executed parts of applications (i.e., hotspots) are conventionally the target of acceleration and that RMS applications are error-tolerant and often take similar input data repeatedly, our proposed accelerator reuses previous computational results of similar enough data to reduce computations. The proposed accelerator is composed of a simple controller and a dedicated memory to store limited sets of previous input data with corresponding computational results in a hotspot. Therefore, this accelerator can be applied to different and/or multiple hotspots/applications only through small extension of the controller, to achieve efficient accelerator design and resolve the design-productivity issue. We conducted quantitative evaluations using a representative RMS application (image compression) to demonstrate the effectiveness of our method over conventional ones with precise computing. Moreover, we provide important findings on parameter exploration for our accelerator design, offering a wider applicability of our accelerator to other applications.