Application mapping onto manycore processor architectures using active search framework

Abstract

Finding an optimal application mapping solution in a manycore processor is an NP-hard problem. Heuristic search techniques have the advantage of finding near-optimal solutions faster than other methods when mapping large-scale applications. However, the majority of the heuristic-based application mapping methods easily fall into local minima. Machine learning (ML) methods can learn heuristics from training data on their own, require minimal assistance from humans, and produce better mapping solutions. Recently, a reinforcement learning-based framework (RLF) has been proposed to generate the initial population for metaheuristics, designed using genetic algorithm (GA) and particle swarm optimization (PSO). The RLF framework does not incorporate reward information while generating mapping solutions. However, the model performance can be improved further by refining the network parameters using the reward information during predictions. To overcome this challenge, we propose an active search framework (ASF). For the first time, we propose a new intellectual property (IP)-core numbering scheme, which will assist ASF in learning the mapping rules more effectively. We demonstrate that REINFORCE with multiple samples (predictions) per data point improves model accuracy and reduces variance by constructing a baseline using these samples. With these, we propose two RL models: active search (ATSR) and active search with pretraining (ATSRP). According to experimental results, both ATSRP and ATSR models produce better mapping solutions compared to RLF and other state-of-the-art methods. The results suggest that the ATSRP model is better suited for performing application mapping onto a 2-D mesh-based manycore processor. Finally, we extend this framework to other performance metrics and 3-D mesh-based manycore processors.