Introduction to the Special Section on USENIX OSDI 2021

This special section of the ACM Transactions on Storage presents some of the highlights of the storage-related papers published in the 15th USENIX Symposium on Operating Systems Design and Implementation (OSDI ’21). The OSDI Symposium emphasizes innovative research as well as quantified or insightful experiences in systems design and implementation. Despite OSDI ’s broad view of the systems area, the design and implementation of storage systems have always been important topics for OSDI. In particular, out of the 165 OSDI ’21 submissions, 26 of them (=16%) addressed various storage-related aspects; out of its 31 accepted papers, 6 (=19%) addressed storage-related themes, constituting a significant part of the OSDI ’21 program. Out of the above, for this special section of ACM Transactions on Storage, we selected two high-quality papers. Each includes some additional material, which has been reviewed (in fasttrack mode) by a subset of its original OSDI ’21 reviewers. The first article is “Nap: Persistent Memory Indexes for NUMA Architectures” by Qing Wang, Youyou Lu, Junru Li, and Jiwu Shu. This is an expanded version of the OSDI ’21 paper “NAP: A Black-Box Approach to NUMA-Aware Persistent Memory Indexes.” It introduces a NUMA-aware layer above existing persistent memory indexes, consisting of a volatile DRAM component and persistent, crash-consistent per-NUMA-node components. Reads and writes to hot items are handled via the NUMA-aware layer, alleviating the performance issues with cross-node access to persistent memory. The second article is “Optimizing Storage Performance with Calibrated Interrupts” by Amy Tai, Igor Smolyar, Michael Wei, and Dan Tsafrir. This paper presents a new interface to help devices make the tradeoff between triggering an interrupt immediately after an I/O request completes, reducing latency, and waiting until multiple interrupts can be coalesced, reducing interrupt-handling overhead. This interface allows applications to inform devices about latency-sensitive requests, allowing interrupt generation to be aligned with application requirements. We hope you enjoy these expanded versions and find both papers interesting and insightful.