Mitigating excessive vCPU spinning in VM-agnostic KVM

In virtualized environments, oversubscribing virtual CPUs (vCPUs) on physical CPUs (pCPUs) is common to utilize CPU resources efficiently. Unfortunately, excessive vCPU spinning, which occurs when a vCPU is waiting in a spin loop for an event from a descheduled vCPU, causes serious performance degradation. Usually, the VM-agnostic hypervisor tries to prevent excessive vCPU spinning by rescheduling vCPUs when an excessive spin is detected by hardware support for virtualization.