HiLFS: FPGA-Orchestrated File System for High-Level Synthesis

Field Programmable Gate Arrays (FPGAs) deliver high performance, and High-Level Synthesis (HLS) simplifies computation description. However, modern FPGA systems cannot directly exploit the convenience and advanced features of contemporary file systems to enable performant, secure, and robust access to high-speed storage devices such as SSDs. This limitation significantly impedes the adoption of FPGAs in data- and I/O-intensive applications, including large language models (LLMs). Existing HLS storage solutions typically either rely on host CPUs to manage file systems via the operating system stack or provide only low-level block access, both of which introduce considerable performance and programmability overheads. Host-mediated access to storage incurs additional latency due to multiple round-trips through the OS kernel on the host CPU, while block-level management on the FPGA side requires substantial engineering efforts that often require recreating file system functionality, such as raw block management, security, and robustness guarantees. These challenges substantially complicate FPGA development and create a 100× gap in scalability compared to GPUs for deploying modern, large-scale machine learning models. To close this gap, we propose HiLFS, the first file system and storage stack for HLS that manages storage entirely within the FPGA. HiLFS exposes a POSIX-like file interface to HLS kernels to ease programming and maintains an on-chip cache of recently accessed file metadata to accelerate file access. It also provides rich file system features, including data integrity, crash consistency, durability guarantees, and efficient concurrent access. As such, HiLFS enables high-performance, secure, and reliable storage management, completely eliminating the need for host intervention. We prototype HiLFS on an AMD/Xilinx Alveo U200 FPGA with a Solidigm DC-P4610 SSD. On Mixtral 8×7B, HiLFS outperforms Nvidia Titan RTX by 1.1/1.3× in performance and 3.0/3.5× in energy efficiency with/without GPUDirect Storage. To the best of our knowledge, this represents the largest-scale LLM deployment on an FPGA to date. Moreover, HiLFS delivers 1.5/1.8× average latency and bandwidth improvements over state-of-the-art commercial CPU-centric storage platforms with/without PCIe P2P, while incurring 13% bandwidth and latency overhead to state-of-the-art HLS low-level block storage works. Furthermore, HiLFS reduces the LoC by 1.5× and 5.3× compared to CPU-centric and block-level storage platforms, respectively.