  Hardware-aware Neural Architecture Search (HW-NAS) is increasingly being used
to design efficient deep learning architectures. An efficient and flexible
search space is crucial to the success of HW-NAS. Current approaches focus on
designing a macro-architecture and searching for the architecture's
hyperparameters based on a set of possible values. This approach is biased by
the expertise of deep learning (DL) engineers and standard modeling approaches.
In this paper, we present a Grassroots Operator Search (GOS) methodology. Our
HW-NAS adapts a given model for edge devices by searching for efficient
operator replacement. We express each operator as a set of mathematical
instructions that capture its behavior. The mathematical instructions are then
used as the basis for searching and selecting efficient replacement operators
that maintain the accuracy of the original model while reducing computational
complexity. Our approach is grassroots since it relies on the mathematical
foundations to construct new and efficient operators for DL architectures. We
demonstrate on various DL models, that our method consistently outperforms the
original models on two edge devices, namely Redmi Note 7S and Raspberry Pi3,
with a minimum of 2.2x speedup while maintaining high accuracy. Additionally,
we showcase a use case of our GOS approach in pulse rate estimation on
wristband devices, where we achieve state-of-the-art performance, while
maintaining reduced computational complexity, demonstrating the effectiveness
of our approach in practical applications.
