Thank you a lot for reporting this issue. I haven't hit it in my environment, but then I only had about 80 guests so far.
Might I ask on the sizes (memory, cpu, #disks) of the guests and the sizing of the host you use? For the ksoftirq the first look to take likely is to check for what softirq (and irq) is currently starting to rise. I'd recommend to start something like http://www-05.ibm.com/de/events/linux-on-system-z/downloads/Tools-MK2-V7-Web.pdf page 79ff. mpstat -I ALL 5 And then raise your load. Gather timestamps when the case was ok, and when it started to become broken. A sysstat along that data with the same timestamps can be useful as well. Please attach that data so we can take a look. In general for KVM exit issues a good thing to do is to get stats on KVM exits. Look at this for a basic info about it https://lwn.net/Articles/513317/ e.g. ./perf kvm stat report --event=vmexit Although in your case for a system your size gathering that can have a serious impact. The stat mentioned above is the lowest overhead of all perf kvm actions, but be careful if you do on a production system. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1646639 Title: KVM CPU slowdown on 4.4 kernel To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1646639/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
