NUTS: A Virtual Machine Scheduler Based On Non-uniform Timeslice Scheduling

In the virtualized environment, the scheduler within the virtual machine moni-tor (VMM) plays a key role in determining the overall allocation of underlying CPUresources and performance of virtual machines (VMs). However, traditional VMMschedulers such as Xen Credit scheduler, which uses the fxed scheduling timeslice toshare the processor resources proportionally among VMs, would cause1) CPU allo-cation error that is the diference between CPU resources a VM requires and actuallyreceives in a given time interval and2) unstability of scheduling latency that is thedelay between a VM waking up and actually running.In this paper，we frst identify two shortcomings in existing VMM. Firstly, thesize of timeslice which is suitable for scheduling VMs confgured with large CPU pro-portional share will make VMs confgured with small CPU proportional share suferextremelylargeCPUallocationerror. Secondly,theschedulerusesthefxedschedulingtimesliceforanyproportionalshareVM,VMsconfguredwithsmallCPUproportionalshare will sufer high scheduling latency.Thenthispaperpresentsaschedulingschemeequippedwithnon-uniformschedul-ing timeslice and implements the prototype on Xen hypervisor. In this scheme, thescheduler allocates CPU resources by using diferent timeslice based on the CPU pro-portional share of VMs to reduce CPU allocation error and the scheduler ensures toschedule each VM at least once in an adjustable time period to achieve stable schedul-ing latency.ExperimentresultsdemonstratethatourschedulingschemelimitstheCPUalloca-tion error to15%and improves the stability of VM scheduling latency. The maximumnetwork packet processing latency is less than30ms. At the same time, the scheduling fairness can be guaranteed and only causes moderate system overhead.