Sommelier: Curating DNN Models for the Masses

Deep learning model repositories are indispensable in machine learning ecosystems today to facilitate model reuse. However, existing model repositories provide a bare-bone interface for model retrieval. The onus is on the user to profile and select from potentially hundreds of choices, barely relieving an average user of the expertise required to design the model in the first place. In this paper, we present Sommelier, an indexing and query system above typical DNN model repositories to interface directly with inference serving or other use cases. Given a desirable accuracy target and resource budget for an inference task category, Sommelier automatically searches through the repository for the most suitable model, without requiring manual profiling from the user. Motivated by manual iterative model search processes and typical model design strategies that generate model variants or models with common segments, Sommelier organizes DNN models based on their semantic correlation, defined as the probability of models producing the same results. This is further combined with a resource index based on relative resource consumption. Sommelier is implemented as a standalone query engine that can interface with an existing repository such as TF-Hub. A case study of 163 models in TF-Hub highlights the extent of model correlation across different model series, suggesting the best candidate model can easily evade manual profiling. Extensive evaluation shows that Sommelier returns the ideal model for over 95% of the queries; When interfaced with an inference server, Sommelier can reduce the 90th percentile tail latency of inference tasks by a factor of 6 via automatic model switching, far more than typical scale-out system optimizations.