[$] Using steal time to moderate CPU demands

Virtualization can increase CPU utilization by allowing a large number ofvirtual CPUs to share a smaller number of physical CPUs. The amount of CPUtime that is actually available does not change, though, so heavy activityon too many virtual CPUs can lead to contention and significant performanceloss. The steal governorpatch series from Shrikanth Hegde is an attempt to address that problemwith a mechanism that allows virtual machines to voluntarily reduce thenumber of virtual CPUs they use when contention is high.