Incorporating Memory Sharing-awareness in Multi-VM Live Migration

One of the key challenges of edge computing is managing the limited resources available at the edge, especially memory and network bandwidth. Virtual machines (VMs) can ensure both isolation and efficient resource utilization within the edge computing infrastructure.Live migration is a crucial technique in edge computing infrastructure to transfer running VMs from one physical node to another. This can occur either within the same host (Intra-host) or between different hosts (Inter-host). Current live migration techniques face challenges, such as lack of awareness of duplicated pages for inter-host migration and inefficient handling of co-located memory for intra-host migration.In this paper, we describe our work on three efficient ways to incorporate sharing-awareness in live migration of multiple VMs while avoiding memory and network resource contention. For inter-host migration, our techniques rely on existing Copy-On-Write (COW) optimization performed by the host/hypervisor. This enables the transfer of a copy of the page only once and preserves existing COW sharing by remapping them at the destination. For intra-host migration, our technique implements a mechanism to identify shared pages and transfer their ownership (via a userfaultfd-based mechanism) instead of copying them. Besides reducing network traffic and memory footprint by eliminating unwanted copying, our techniques also result in a shorter total migration time, thereby freeing additional resources involved in migration as quickly as possible.