HyQ: Hybrid I/O Queue Architecture for NVMe over Fabrics to Enable High- Performance Hardware Offloading

NVMe over Fabrics (NVMe-oF) has been widely applied as a remote storage protocol in cloud computing. The existing NVMe-oF software stack consumes a large number of CPU resources. Emerging devices, such as Smart NICs and DPUs, have supported hardware offloading of NVMe-oF to free these valuable CPU cores. However, NVMe-oF offloading capacity is always compromised because of limited hardware resources on design. Additionally, from thorough evaluations, we found that NVMe-oF inevitably suffers from severe performance degradation on complex application I/O patterns when using hardware offloading. It is challenging to achieve high performance and fully utilize NVMe-oF offloading simultaneously. In this paper, we propose HyQ, a novel hybrid I/O queue architecture for NVMe-oF, to achieve high performance while gaining the advantages of hardware offloading. HyQ realizes the coexistence of hardware offloading and software non-offloading queues, thus enabling the dynamic dispatching of I/O requests to appropriate processing queues according to user-defined I/O scheduling policies. Additionally, HyQ provides a request scheduling framework to support customized schedulers that select appropriate queues for I/O requests. In our evaluation, HyQ achieves up to 1.91x IOPS and 8.36x bandwidth performance improvement over the original hardware offloading scheme.