Enable PV EOI enhancement for a VM, and verify it cuts down on VM exits (and hence improves performance).
Nothing beyond the initial test day setup (basically a function F18 VM).
How to test
- Start a guest. It should be the only guest running. Connect to the graphical console with virt-manager, log in and open a terminal
- Inside the guest, do
- Back on the host machine, yum install -y perf
- Run the following perf command as root
perf stat --event "kvm:*" --all-cpus sleep 10
- Notice the values for kvm_entry/kvm_exit (mine were around 110,000)
- Shutdown the guest
- Enable PV EOI
# virsh edit f18
Check <apic/> to <apic eoi="on"/>
- Save and exit
- Start the guest, connect with virt-manager, and restart the ping command
- Run the perf command again on the host
- View reduced entry/exit count (mine was around 30,000, over 70% reduction)
No obvious errors occur, entry/exit are reduced by a noticeable amount.