A quantifiable approach to approximate computing: special session

Approximate computing has applications in areas such as image processing, neural computation, distributed systems, and real-time systems, where the results may be acceptable in the presence of controlled levels of error. The promise of approximate computing is in its ability to render just enough performance to meet quality constraints. However, going from this theoretical promise to a practical implementation requires a clear comprehension of the system requirements and matching them to the design of approximations as the system is implemented. This involves the tasks of (a) identifying the design space of potential approximations, (b) modeling the injected error as a function of the level of approximation, and (c) optimizing the system over the design space to maximize a metric, typically the power savings, under constraints on the maximum allowable degradation. Often, the error may be introduced at a low level of design (e.g., at the level of a full adder) but its impact must be percolated up to system-level error metrics (e.g., PSNR in a compressed image), and a practical approach must devise a coherent and quantifiable way of translating between error/power tradeoffs at all levels of design.