TrackFM: Far-out Compiler Support for a Far Memory World

Large memory workloads with favorable locality of reference can benefit by extending the memory hierarchy across machines. Systems that enable such far memory configurations can improve application performance and overall memory utilization in a cluster. There are two current alternatives for software-based far memory: kernel-based and library-based. Kernel-based approaches sacrifice performance to achieve programmer transparency, while library-based approaches sacrifice programmer transparency to achieve performance. We argue for a novel third approach, the compiler-based approach, which sacrifices neither performance nor programmer transparency. Modern compiler analysis and transformation techniques, combined with a suitable tightly-coupled runtime system, enable this approach. We describe the design, implementation, and evaluation of TrackFM, a new compiler-based far memory system. Through extensive benchmarking, we demonstrate that TrackFM outperforms kernel-based approaches by up to 2× while retaining their programmer transparency, and that TrackFM can perform similarly to a state-of-the-art library-based system (within 10%). The application is merely recompiled to reap these benefits.