Continuous real-world inputs can open up alternative accelerator designs

  • Authors:
  • Bilel Belhadj;Antoine Joubert;Zheng Li;Rodolphe Héliot;Olivier Temam

  • Affiliations:
  • CEA LETI, France;CEA LETI, France;INRIA, Saclay, France;CEA LETI, France;INRIA, Saclay, France

  • Venue:
  • Proceedings of the 40th Annual International Symposium on Computer Architecture
  • Year:
  • 2013

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Abstract

Motivated by energy constraints, future heterogeneous multi-cores may contain a variety of accelerators, each targeting a subset of the application spectrum. Beyond energy, the growing number of faults steers accelerator research towards fault-tolerant accelerators. In this article, we investigate a fault-tolerant and energy-efficient accelerator for signal processing applications. We depart from traditional designs by introducing an accelerator which relies on unary coding, a concept which is well adapted to the continuous real-world inputs of signal processing applications. Unary coding enables a number of atypical micro-architecture choices which bring down area cost and energy; moreover, unary coding provides graceful output degradation as the amount of transient faults increases. We introduce a configurable hybrid digital/analog micro-architecture capable of implementing a broad set of signal processing applications based on these concepts, together with a back-end optimizer which takes advantage of the special nature of these applications. For a set of five signal applications, we explore the different design tradeoffs and obtain an accelerator with an area cost of 1.63mm2. On average, this accelerator requires only 2.3% of the energy of an Atom-like core to implement similar tasks. We then evaluate the accelerator resilience to transient faults, and its ability to trade accuracy for energy savings.