BHerd: Accelerating Federated Learning by Selecting Beneficial Herd of Local Gradients

In the domain of computer architecture, Federated Learning (FL) is a paradigm of distributed machine learning in edge systems. However, the systems’ Non-Independent and Identically Distributed (Non-IID) data negatively affect the convergence efficiency of the global model, since only a subset of these data samples is beneficial for accelerating model convergence. In pursuit of this subset, a reliable approach involves determining a measure of validity to rank the samples within the dataset. In this paper, we propose the BHerd strategy, which selects a beneficial herd of local gradients to accelerate the convergence of the FL model. Specifically, we map the distribution of the local dataset to the local gradients and use the Herding strategy to obtain a permutation of the set of gradients, where the more advanced gradients in the permutation are closer to the average of the set of gradients. These top portions of the gradients will be selected and sent to the server for global aggregation. We conduct experiments on different datasets, models, and scenarios by building a prototype system, and experimental results demonstrate that our BHerd strategy is effective in selecting beneficial local gradients to mitigate the effects brought by the Non-IID dataset.