Harmonia: An Interference-Aware Dynamic I/O Scheduler for Shared Non-volatile Burst Buffers

Abstract

Modern HPC systems employ burst buffer installations to reduce the peak I/O requirements for external storage and deal with the burstiness of I/O in modern scientific applications. These I/O buffering resources are shared between multiple applications that run concurrently. This leads to severe performance degradation due to contention, a phenomenon called cross-application I/O interference. In this paper, we first explore the negative effects of interference at the burst buffer layer and we present two new metrics that can quantitatively describe the slowdown applications experience due to interference. We introduce Harmonia, a new dynamic I/O scheduler that is aware of interference, adapts to the underlying system, implements a new 2-way decision-making process and employs several scheduling policies to maximize the system efficiency and applications' performance. Our evaluation shows that Harmonia, through better I/O scheduling, can outperform by 3× existing state-of-the-art buffering management solutions and can lead to better resource utilization.