LEAP Shared Memories: Automating the Construction of FPGA Coherent Memories

Parallel programming has been widely used in many scientific and technical areas to solve large problems. While general-purpose processors have rich infrastructure to support parallel programming on shared memory, such as coherent caches and synchronization libraries, parallel programming infrastructure for FPGAs is limited. Thus, development of FPGA-based parallel algorithms remains difficult. In this work, we seek to simplify parallel programming on FPGAs. We provide a set of easy-to-use declarative primitives to maintain coherency and consistency of accesses to shared memory resources. We propose a shared-memory service that automatically manages coherent caches on multiple FPGAs. Experimental results of a 2-dimensional heat transfer equation show that the shared memory service with our distributed coherent caches outperforms a centralized cache by 2.6x. To handle synchronization, we provide new lock and barrier primitives that leverage native FPGA communication capabilities and outperform traditional through-memory primitives by 1.8x.