Sustainable Hardware Specialization

TL;DR

This paper investigates how reconfigurable hardware can replace dedicated accelerators to reduce the environmental footprint of specialized hardware in modern SoCs, demonstrating significant sustainability benefits.

Contribution

It introduces an analytical model and hardware synthesis results showing that reconfigurable accelerators are more sustainable than dedicated accelerators, reducing environmental impact.

Findings

Replacing dedicated accelerators with reconfigurable fabric reduces environmental footprint by 2.5 to 7.6 times.

As few as 12 accelerators can be replaced by a CGRA for sustainability benefits.

Reconfigurable hardware offers a scalable solution for sustainable hardware specialization.

Abstract

Hardware specialization is commonly viewed as a way to scale performance in the dark silicon era with modern-day SoCs featuring multiple tens of dedicated accelerators. By only powering on hardware circuitry when needed, accelerators fundamentally trade off chip area for power efficiency. Dark silicon however comes with a severe downside, namely its environmental footprint. While hardware specialization typically reduces the operational footprint through high energy efficiency, the embodied footprint incurred by integrating additional accelerators on chip leads to a net overall increase in environmental footprint, which has led prior work to conclude that dark silicon is not a sustainable design paradigm. We explore sustainable hardware specialization through reconfigurable logic that has the potential to drastically reduce the environmental footprint compared to a sea of accelerators by amortizing its embodied footprint across multiple applications. We present an abstract analytical model that evaluates the sustainability implications of replacing dedicated accelerators with a reconfigurable accelerator. We derive hardware synthesis results on ASIC and CGRA (a representative reconfigurable fabric) for chip area and energy numbers for a wide variety of kernels. We input these results to the analytical model and conclude that reconfigurable fabric is more sustainable. We find that as few as a handful to a dozen accelerators can be replaced by a CGRA. Moreover, replacing a sea of accelerators with a CGRA leads to a drastically reduced environmental footprint (by a factor of $2.5 \times$ to $7.6 \times$).