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.

  • Lesson learned? Do not put ANY time critical things on a VM. Period. – TomTom Nov 28 '16 at 13:07
  • The software who is running is Cloud certificated, so it must be possible to run it in a VM. The virtualization is not the problem, when I run other VMs with high CPU load, it have no effect at all. At the moment I only make a long time test, so in the worst situation I always can change back to a physical computer. My goal is to run it on a other server, where is less activities on the host side, but before this I need to be sure that I get it to work. Beside this, in 2010/11 you found already presentations where people use KVM for real time processes. – jb_alvarado Nov 28 '16 at 13:15
  • Current KVM version? All drivers up to date? Certification is also for KVM? Kernel configured for fast response time? We lack information to do anything but guess. – TomTom Nov 28 '16 at 13:26
  • I update my post with KVM version and driver Information. About the cloud certification, here is what the vendor says: Cinegy Air PRO can run in a VMWARE ESX, Microsoft Hyper-V, Citrix XenServer virtual environment (VM) and is available on Amazon Web Services Marketplace as well. KVM is not listed, but I don't belief this is a problem. I have not make Kernel configurations, when there is a chance to do this without recompiling, I really would like to know this. Using centos can also be a option, if this is better in KVM. – jb_alvarado Nov 28 '16 at 13:45
  • It may well be a problem with KVM at this point. I am inclined to close - we do not deal with "hack" configs (require: best business practices) and KVM is not a supported hypervisor. But I will leave it. This really could be a driver problem. I suggest trying with Hyper-V (free trial available) or any supported hypervisor to validate. – TomTom Nov 28 '16 at 13:49

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.