Zero2M: Optimizing Tenant-Level I/O Management for Future Faster NVMe Storage with FPGA

High-speed Non-Volatile Memory Express (NVMe) Solid-State Drives (SSDs) are shared by multiple tenants in cloud scenarios to improve resource utilization. Tenant-level I/O management is necessary to achieve reliable QoS control during sharing. Unfortunately, our investigation finds that CPUs inevitably participate in I/O management for existing solutions because SSDs are not tenant-sensitive and have limited internal computing resources. It introduces additional CPU costs and latency overhead when serving future faster SSDs. We propose that the Field Programmable Logic Gate Array (FPGA) is a promising alternative for freeing tenant-level I/O management from CPUs. However, implementing tenant-level I/O management using the FPGA requires addressing the following challenges: (1) System compatibility and tenant identification; (2) Efficient FPGA workflows that will not become a bottleneck; (3) Fast I/O management workflow that introduces the lowest additional CPU costs and latency. This article presents Zero2M, a novel CPU-free system designed to optimize the additional CPU costs and latency overhead in tenant-level I/O management for future faster NVMe SSDs. Zero2M proposes a dedicated FPGA-based NVMe controller to preserve system compatibility and identify tenants using the namespace mechanism in NVMe. It allows I/O management without modifying host software, which existing solutions cannot achieve. The parallelized and pipelined workflows are proposed in the controller to accelerate I/O command processing and prevent the controller from becoming a bottleneck for the I/O management workflow. The read/write speed of the Zero2M controller is 4.65 \(\times\) /4.92 \(\times\) faster than the state-of-the-art hardware-accelerated controller. The I/O management workflow is formulated as a novel parallelized and pipelined accelerator and integrated into the workflow of Zero2M’s controller. It optimizes additional CPU costs and latency overhead for tenant-level I/O management. Experiments present that Zero2M reduces an average of 3.01 \(\times\) CPU usage while maintaining the lowest latency overhead (7.62 \(\times\) lower on average) compared to the state-of-the-art solution. It also removes the CPU dependency for tenant-level I/O management for the first time.