When vcpus are pinned to pcpus, there is a 50% chance that a guest'sWe only tried windows 2003 for the experiments, and have no data related to windows 2008.
vcpus will be co-scheduled and spinlocks will perform will.
When vcpus are not pinned, but affine wakeups are disabled, there is a
33% chance that vcpus will be co-scheduled.
When vcpus are not pinned and affine wakeups are enabled there is a 0%
chance that vcpus will be co-scheduled.
Keeping both vcpus on the same core actually makes sense since they
can communicate through the local cache faster than across cores.
What we need is to make sure that they don't spin.
Windows 2008 can report spinlock spinning through a hypercall. Can
you hook to that interface and see if it happens regularly?
Altenatively use a PLE capable host and trace the kvm_vcpu_on_spin()
function.
But maybe we can have a try later. Anyway, the key point is we have to enhance the scheduler to let it
Know which threads are vcpu threads to avoid perf loss in this case.