Self-boosted Co-scheduling for SMP Virtual Machines

In this paper, we propose a self-boosted co-scheduling(SBCO) algorithm to reduce synchronization latency among consolidated virtual machines. Different from conventional co-scheduling which requires all runnable sibling vCPUs that are from the same VM to be scheduled at precisely the same time, SBCO reorders all these sibling vCPUs threads coarsely at the same level in their respective run queue, then schedules them at the same time window, and maintains global fairness between consolidated VMs. SBCO minimizes costly pCPU preemption and preserves the flexibility of the dynamic mapping between vCPUs and pCPUs. We have implemented SBCO in KVM and conducted comprehensive evaluations with various workloads. Results shows that SBCO is able to reduce the number of context switches significantly and achieve overall performance improve up to 10% compared with other competitors and improve up to 60% compared with the default scheduler.