Optimization Research on Processes I/O Performance in Container-level Virtualization

As representative of container-level virtualization, the core idea of OpenVZ group scheduling is fairness. System ensures CPU time is shared fairly among virtual containers and among processes belonging to the same container. Thus processes may not be scheduled immediately when awakened by I/O, affecting their responsiveness and I/O throughput. If breaking this kind of absolute fairness and permitting processes to deal with current burst I/O events by borrowing their future time temporarily, I/O performance will be improved. The approach also does not destroy system fairness in the long run. The paper analyses OpenVZ group scheduling and points out factors that affect I/O performance of processes in virtual containers. To solve these problems, we make two layers of optimization. In virtual container layer, we implement container preemption based on I/O by priority queue, in bottom layer, we still permit optimized processes to take precedence over other processes to use CPU in the case of continuous I/O, also maintaining original time mechanism and minimizing system modification. We evaluate network response time, network throughput, block I/O throughput, test results demonstrate at the scheduling cost of 2.9% processes' I/O performance is ameliorated remarkably.