Optimize Performance of Virtual Machine Checkpointing via Memory Exclusion

Virtual machine (VM) level checkpoints bring several advantages which process-level checkpoint implementation can hardly provide: compatibility, transparence, flexibility, and simplicity. However, the size of VM-level checkpoint may be very large and even in the order of gigabytes. This disadvantage causes the VM checkpointing and restart time become very long. To reduce the size of VM checkpoint, this paper proposes a memory exclusion scheme using ballooning mechanism, which omits saving unnecessary free pages in the VM. We implement our prototype in Xen environment. Experimental measurements show our approach can significantly reduce the size of VM checkpoint with minimal runtime overhead, thereby greatly improve the checkpoint performance.