Stretch: A Fault-Driven DSM Runtime for Distributed Multithreaded Applications

Abstract

Recent Linux memory-management interfaces make it practical to revisit distributed shared memory (DSM) as a deployable runtime substrate for conventional multithreaded software. We present Stretch, a userspace fault-driven page-granularity DSM runtime that combines userfaultfd-based fault interception, centralized MSI-style coherence (i.e., Modified, Shared, or Invalid), and CRIU-based thread placement to extend a process across multiple machines. Missing-page and write-protection faults are translated into fetch, invalidation, and ownership-transfer operations, while distributed barriers and coarse-grained mutexes reuse the same mechanism. Stretch supports both automatic tracking of anonymous regions and an explicit tracked-region mode that focuses coherence on genuinely shared memory.