NAFS : Stackable Filesystem for Maximizing Local Access in a NUMA System

Seungjun Ha, Hobin Woo, Euiseong Seo, Beomseok Nam

http://doi.org/10.5626/JOK.2021.48.6.612

Intel Optane DC Persistent Memory has read/write latencies comparable to DRAM but ensures data persistence as in block devices such as SSD. However, Optane DC PM modules are installed in DIMM slots of NUMA nodes but legacy block devices are installed in PCIe or SATA. Therefore, Optane DC PMs are known to suffer from the NUMA effects, and the performance of a multithreaded application depends on the NUMA locality. In this paper, we propose a novel stackable file system, NUMA-Aware Filesystem (NAFS). NAFS divides a file into segment units such that I/Os can be performed in local NUMA nodes where each application thread runs. To enable this feature, NAFS duplicates the file metadata across all NUMA nodes if the number of remote I/Os exceeds a certain threshold. Our performance study shows NAFS reduces the number of accesses to remote NUMA nodes significantly, improving the performance of multithreaded applications.