The Data Conversion Bottleneck in Analog Computing Accelerators
Keywords: Domain Specific Computing Accelerator, Analog Computing, Optical Computing, Fourier Transform, Convolution, Analog to Digital, Digital to Analog
TL;DR: Converting data from analog to digital and digital to analog is a huge problem for analog computing accelerators. We need to think carefully about how to architect analog computing accelerators to avoid or mitigate this problem.
Abstract: Most modern computing tasks have digital electronic input and output data.
Due to these constraints imposed by real-world use cases of computer systems, any analog computing accelerator, whether analog electronic or optical, must perform an analog-to-digital conversion on its input data and a subsequent digital-to-analog conversion on its output data.
The energy and latency costs incurred by data conversion place performance limits on analog computing accelerators.
To avoid this overhead, analog hardware must replace the full functionality of traditional digital electronic computer hardware.
This is not currently possible for optical computing accelerators due to limitations in gain, input-output isolation, and information storage in optical hardware.
This article presents a case study that profiles 27 benchmarks for an analog optical Fourier transform and convolution accelerator which we designed and built.
The case study shows that an ideal optical Fourier transform and convolution accelerator can produce an average speedup of $9.4 \times$ and a median speedup of $1.9 \times$ for the set of benchmarks.
The optical Fourier transform and convolution accelerator only produces significant speedup for pure Fourier transform ($45.3 \times$) and convolution ($159.4 \times$) applications.
Submission Number: 13
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