Is co-scheduling too expensive for SMP VMs?

Symmetric multiprocessing (SMP) virtual machines (VMs) allow users to take advantage of a multiprocessor infrastructure. Despite the advantage, SMP VMs can cause synchronization latency to increase significantly, depending on task scheduling. In this paper, we show that even if a SMP VM runs non-concurrent applications, the synchronization latency problem can still occur due to synchronization in the VM kernel. Our experiments show that both of the widely used open source hypervisors, Xen and KVM, with the default schedulers are susceptible to the synchronization latency problem. To remediate this problem, previous works propose a co-scheduling solution where virtual CPUs (vCPUs) of a SMP VM are scheduled simultaneously. However, the co-scheduling approach can cause CPU fragmentation that reduces CPU utilization, priority inversion that degrades I/O performance, and execution delay, leading to deployment impediment. We propose a balance scheduling algorithm which simply balances vCPU ...

• Type: Journal
• Year: 2011
• Where: EUROSYS
• Authors: Orathai Sukwong, Hyong S. Kim
• Keywords: EUROSYS 2011, Execution Delay, Priority Inversion, Software Engineering, Symmetric Multiprocessing