FastXenBlk: high-performance virtualized disk IOs without compromising isolation

Damien Thenot (1) , Jean-Pierre Lozi (2) , Gaël Thomas (3, 4, 5)

1 Vates SAS
2 Whisper - Well Honed Infrastructure Software for Programming Environments and Runtimes
3 IP Paris - Institut Polytechnique de Paris
4 TSP - INF - Département Informatique
5 BENAGIL - Efficient and safe distributed systems

Optimizing IO in a type I hypervisor such as Xen is difficult because of the cost of exchanging data between a VM and the driver. We address this challenge by proposing FastXenBlk, a new IO driver for Xen. FastXenBlk uses three mechanisms to improve IO performance. First, it uses several threads that poll multiple virtual IO queues that are exposed to a guest in order to execute IOs in parallel. Second, it batches requests in order to minimize the number of hypercalls to Xen. And third, it uses kernel bypass in order to avoid system calls during IOs. We evaluate FastXenBlk using the FIO benchmark with different access patterns and IO sizes. Our evaluation shows that FastXenBlk consistently improves the latency and the throughput for all workloads as compared to tapdisk, the driver currently used in production, by a factor of up to 3×.

Keywords: Computing methodologies; Software and its engineering; Software notations and tools; Software organization and properties; Contextual software domains; Operating systems; Extra-functional properties; General and reference; Cross-computing tools and techniques; Performance

Domains: Computer Science [cs]

Damien Thenot, Jean-Pierre Lozi, Gaël Thomas. FastXenBlk: high-performance virtualized disk IOs without compromising isolation. The 24th International Middleware Conference: Industrial Track (Middleware '23), Dec 2023, Bologna, Italy. pp.42-48, ⟨10.1145/3626562.3626834⟩. ⟨hal-04354563⟩