Spintastic: Spin-based stochastic logic for energy-efficient computing

Spintronics is one of the leading technologies under consideration for the post-CMOS era. While spintronic memories have demonstrated great promise due to their density, non-volatility and low leakage, efforts to realize spintronic logic have been much less fruitful. Recent studies project the performance and energy efficiency of spintronic logic to be considerably inferior to CMOS. In this work, we explore Stochastic Computing (SC) as a new direction for the realization of energy-efficient logic using spintronic devices. We establish the synergy between stochastic computing and spintronics by demonstrating that (i) the peripheral circuits required for SC to convert to/from stochastic domains, which incur significant energy overheads in CMOS, can be efficiently realized by exploiting the characteristics of spintronic devices, and (ii) the low logic complexity and finegrained parallelism in SC circuits can be leveraged to alleviate the shortcomings of spintronic logic. We propose Spintastic, a new design approach in which all the components of stochastic circuits - stochastic number generators, stochastic arithmetic units, and stochastic-to-binary converters - are realized using spintronic devices. Our experiments on a range of benchmarks from different application domains demonstrate that Spintastic achieves 2.8X improvement in energy over CMOS stochastic implementations and 1.9X over a CMOS binary baseline.