Exploiting CXL-based Memory for Distributed Deep Learning.

Deep learning (DL) is being widely used to solve complex problems in scientific applications from diverse domains, such as weather forecasting, medical diagnostics, and fluid dynamics simulation. DL applications consume a large amount of data using large-scale high-performance computing (HPC) systems to train a given model. These workloads have large memory and storage requirements that typically go beyond the limited amount of main memory available on an HPC server. This significantly increases the overall training time as the input training data and model parameters are frequently swapped to slower storage tiers during the training process. In this paper, we use the latest advancements in the memory subsystem, specifically Compute Express Link (CXL), to provide additional memory and fast scratch space for DL workloads to reduce the overall training time while enabling DL jobs to efficiently train models using data that is much larger than the installed system memory. We propose a framework, called DeepMemoryDL, that manages the allocation of additional CXL-based memory, introduces a fast intermediate storage tier, and provides intelligent prefetching and caching mechanisms for DL workloads. We implement and integrate DeepMemoryDL with a popular DL platform, TensorFlow, to show that our approach reduces read and write latencies, improves the overall I/O throughput, and reduces the training time. Our evaluation shows a performance improvement of up to 34% and 27% compared to the default TensorFlow platform and CXL-based memory expansion approaches, respectively.