Optimized pre-copy live migration for memory intensive applications

Abstract

Live migration is a widely used technique for resource consolidation and fault tolerance. KVM and Xen use iterative pre-copy approaches which work well in practice for commercial applications. In this paper, we study pre-copy live migration of MPI and OpenMP scientific applications running on KVM and present a detailed performance analysis of the migration process. We show that due to a high rate of memory changes, the current KVM rate control and target downtime heuristics do not cope well with HPC applications: statically choosing rate limits and downtimes is infeasible and current mechanisms sometimes provide suboptimal performance. We present a novel on-line algorithm able to provide minimal downtime and minimal impact on end-to-end application performance. At the core of this algorithm is controlling migration based on the application memory rate of change.