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Tuesday, July 9 • 11:40am - 12:10pm
EvFS: User-level, Event-Driven File System for Non-Volatile Memory

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The extremely low latency of non-volatile memory (NVM) raises issues of latency in file systems. In particular, user-kernel context switches caused by system calls and hardware interrupts become a non-negligible performance penalty. A solution to this problem is using direct-access file systems, but existing work focuses on optimizing their non-POSIX user interfaces. In this work, we propose EvFS, our new user-level POSIX file system that directly manages NVM in user applications. EvFS minimizes the latency by building a user-level storage stack and introducing asynchronous processing of complex file I/O with page cache and direct I/O. We report that the event-driven architecture of EvFS leads to a 700-ns latency for 64-byte non-blocking file writes and reduces the latency for 4-Kbyte blocking file I/O by 20 us compared to a kernel file system with journaling disabled.


Takeshi Yoshimura

IBM Research - Tokyo

Tatsuhiro Chiba

IBM Research - Tokyo

Hiroshi Horii

IBM Research - Tokyo

Tuesday July 9, 2019 11:40am - 12:10pm PDT
HotStorage: Grand Ballroom I–III