Efficient Versioning for Unikernels

cloud-computing; libraryos; statically-linked; Unikernels; versioning; virtualization; Address space; Cloud-computing; Fast start-up; Libraryos; Low memory; Memory consumption; Statically-linked; Unikernel; Versioning; Virtualizations; Software; Information Systems; Artificial Intelligence

Abstract :

[en] Unikernels are specialized, single-address-space op-erating systems (OSes) tailored to specific applications. They offer strong isolation, low memory/disk footprints, and fast startup times-making them well-suited for cloud and serverless computing. However, deploying many of them at scale in cloud environments introduces new challenges. In particular, managing library updates and versioning in statically linked unikernels is difficult due to their tightly coupled structure. Unlike dynamically linked binaries, statically linked unikernels lack built-in versioning mechanisms. Consequently, even minor library changes result in entirely new memory layouts, which can significantly increase memory consumption when multiple instances run concurrently. We present Spacer-A, a framework that improves memory sharing across statically linked unikernels with different library versions. Spacer uses differential analysis and library align-ment to enable page-level sharing via memory deduplication scanners or a custom loader backed by a shared library pool. Our evaluation with Unikraft shows that Spacer reduces memory consumption and boot overhead while maintaining compatibility across versions. The framework integrates into existing unikernel build pipelines with minimal changes and is released as open source.

Disciplines :

Computer science

Author, co-author :

Gain, Gaulthier ; Université de Liège - ULiège > Montefiore Institute of Electrical Engineering and Computer Science

Knott, Benoît ; Université de Liège - ULiège > Montefiore Institute of Electrical Engineering and Computer Science

Mathy, Laurent ; Université de Liège - ULiège > Département d'électricité, électronique et informatique (Institut Montefiore) > Systèmes informatiques répartis et sécurité

Language :

English

Title :

Efficient Versioning for Unikernels

Publication date :

07 July 2025

Event name :

2025 IEEE 18th International Conference on Cloud Computing (CLOUD)

Event organizer :

IEEE

Event place :

Helsinki, Fin

Event date :

from 7th to 12 July 2025

By request :

Yes

Audience :

International

Main work title :

Proceedings - 2025 IEEE 18th International Conference on Cloud Computing, CLOUD 2025

Editor :

Chang, Rong N.

Publisher :

IEEE Computer Society

ISBN/EAN :

9798331555573

Peer review/Selection committee :

Peer reviewed

Additional URL :

http://xplorestaging.ieee.org/ielx8/11120532/11120459/11120588.pdf?arnumber=11120588

Funding text :

IEEE Computer Society and the Technical Committee on Services Computing (TCSVC)

Available on ORBi :

since 06 February 2026

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