I running here Ubuntu 16.04 as KVM Host. In a VM runs Windows with a time critical process (UDP Video Stream)
Sometime when other process runs on the host, for a moment it influence the CPU usage from the VM so that I get a short error in my stream.
I play with renice (-10), ionice and chrt (-r -p 70), but it have only a little impact. It looks like, the the CPU scheduler need a short moment to set prioritization and that moment is to long. But I don't now, I'm not a kernel expert.
My VMs have not more CPU cores then my host have, in reality there are two left, and the average CPU usage is around 20%. On the host runs also DHCP, DNS and spuid/squidguard and some crons, but all have no much cpu usage. I can also simulate a error with stress -c 6, for example.
Is there a way to stabilize the CPU usage for the VM?
I thought on cpu pinning, but some people don't recommend this.
KVM Version is 2.5, and on Windows all virtio driver a new.