Improving I/O Performance and Fairness in NVMe SSDs With Pooling Portions of Cache Partitions

Nonvolatile memory express (NVMe) solid-state drives (SSDs) have become mainstream storage devices in today’s computing systems, due to their high throughput and ultralow latency. It has been observed that the impact of interference among all concurrently running streams (i.e., I/O workloads) on their overall responsiveness differs significantly in multistream SSDs, resulting in unfairness. This article proposes a cache division management scheme built on top of the evenly partition scheme for NVMe SSDs, to enhance I/O responsiveness without consciously sacrificing fairness. To this end, we first build a mathematical model to directly cut portions from the Local cache partitions allocated to concurrently running streams, considering their run-time performance measures. Then, our approach pools these portions together for the use of all streams. As a result, each stream has its corresponding Local cache space for ensuring fairness, meanwhile the pooled Global cache space is shared by all streams for enhancing I/O responsiveness. Trace-driven simulation experiments demonstrate that our proposal reduces the overall I/O latency by up to 24.4%, and improve the measure of fairness by $\mathtt{2.5}\times $ on average, in contrast to existing cache management schemes for NVMe SSDs.