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UBC Theses and Dissertations

Offloading embedding lookups to processing-in-memory for deep learning recommender models Zarif, Niloofar

Abstract

Recommender systems are an essential part of many industries and businesses. Generating accurate recommendations is critical for user engagement and business revenue. Currently, deep learning recommender models are commonly used, but they face challenges in processing and representing categorical data, which is a significant portion of the data used by these models. Embedding layers are often used to handle these complications by storing the numerical representation of different categories of a feature in a reduced vector space. Vectors representing all the categories of a feature in the reduced vector space will be stored in a tabular structure named embedding table. The operation of fetching the vector representation of a category from the embedding table and pooling them is called embedding lookup. However, embedding lookups have large memory footprints and require high memory bandwidth, leading to high latency and low throughput. We have developed a new system called PIM-Rec to address these challenges by using the first commercially available Processing-In-Memory (PIM) capable DRAM modules for embedding lookups. PIM-Rec is the first system to use such DRAM modules, and it has shown an 80% decrease in end-to-end inference cycle latency and an 80% increase in latency-bound throughput compared to the standard CPU-only implementation. PIM DRAM modules are a good candidate for handling embedding lookups, especially with the recent drastic size increase of embedding tables. Although PIM-Rec faced obstacles, it offers a realistic solution and analysis while discovering the obstacles and projecting them. This new system provides a promising solution for improving the efficiency of recommender systems and reducing the load they incur in data centers.

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Attribution-NonCommercial-NoDerivatives 4.0 International