cInterrupts: Calibrated Interrupts for Low-Latency Storage Devices

NVMe devices have limited control over completion notification, resulting in reduced performance or excessive interrupts. Instead of relying on heuristics or static configurations to determine when to coalesce interrupts, we propose a much simpler solution: let the application tell the device when it should be notified. Our system, cInterrupts, provides this information by adding merely two bits, known as hints, to each request. We show that combined with a new adaptive coalescing policy for NVMe, cInterrupts greatly improves performance in high throughput workloads while providing better fairness in mixed workloads.