FusionFS: Fusing I/O Operations using CISCops in Firmware File Systems

We present FusionFS, a direct-access firmware-level in-storage filesystem that exploits near-storage computational capability for fast I/O and data processing, consequently reducing I/O bottlenecks. In FusionFS, we introduce a new abstraction, CISCop which combines multiple I/O and data processing operations into one fused operation and offloads them for near-storage processing. By offloading, CISCops significantly reduces dominant I/O overheads such as system calls, data movement, communication, and other software overheads. Further, to enhance the use of CISCop we introduce MicroTx, a fine-grained crash consistency and fast (automatic) recovery mechanism for both I/O and data processing operations. Finally, we explore efficient and fair use of in storage compute resources by proposing a novel Completely Fair Scheduler (CFS) for in-storage compute and memory resources across tenants. Evaluation of FusionFS against the state-of-the-art user-level, kernel-level, and firmware-level file systems using microbenchmarks, macrobenchmarks, and real-world applications shows up to 6.12x, 5.09x, and 2.07x performance gains, and 2.65x faster recovery.