Friday, May 13, 2016

quick debugging KVM VM issues

See a hang or infinite loop, or perf issue with VM on KVM? Here's how to get a trace of it so a bugzilla report can be meaningful:

First attach VM configuration XML. That is obtained by:

>  sudo virsh dumpxml [vm_name] > some_file

Cole Robinson wrote on 09/23/2014 04:24 PM:
> sudo debuginfo-install qemu-system-x86
> Then on the next hang, grab the pid of the busted VM from ps axwww, and do:
> sudo pstack $pid
> The dump that output in a bug report, along with
> /var/log/libvirt/qemu/$vmname.log. File it against qemu

Also interesting might be system log from Host and guest. On Fedora you can obtain it by a command similar to:

> sudo journalctl --system --since today

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