[libvirt-users] Networking issues in host

Martin Kletzander mkletzan at redhat.com
Mon Mar 30 11:31:06 UTC 2015

Since you have low expectations, I'll just try to point out the
obvious places to look at ;)

I'm not sure how stopping of libvirt works in Arch, but there _might_
be few things libvirt leaves running on purpose (i.e. that's not a
bug).  For example, if you have a network on autostart or some VM,
which I don't suppose you do, they might be running.  That's the case
of the default network for example.  Look if there's a dnsmasq running
or some iptables rules left out.  If yes, try destroying the network.
There is near-zero probability that this is the cause, but it's not
zero since there might be some dnsmasq bug, for example.  If that
doesn't help, just try looking at the differences libvirt's start/stop
does in the system instead of looking at what part of the system looks
busy (e.g. with atop).

On Sun, Mar 29, 2015 at 09:24:56AM -0700, G. Richard Bellamy wrote:
>I realize this falls under the category of "so incredibly vague I
>should maybe not send it", so I have low expectations and apologize
>beforehand if it's just pure noise.
>That being said - it appears that the whole HOST system becomes laggy.
>It can effect the mouse, the keyboard, the network. There are no
>messages in the logs that I can find that indicate the system is
>blocked or hung or dumping core - and frankly I just don't know where
>to start troubleshooting something like this when there's absolutely
>no indication in the logs that things are struggling.
>What I DO know about the symptoms:
>1. happen after an indeterminate period of time
>2. continue even if I shutdown libvirtd and the two guests - a reboot
>3. do NOT occur if I leave libvirtd disabled and NEVER start it
>Which, on review, seems it might have something to do with the KVM
>kernel module - so I'm copying that mailing list as well.
>root at eanna i ~ # pacman -Qi linux
>Name           : linux
>Version        : 3.18.6-1
>Description    : The Linux kernel and modules
>Architecture   : x86_64
>Build Date     : Fri 06 Feb 2015 11:46:13 PM PST
>Install Date   : Thu 19 Mar 2015 03:58:50 PM PDT
>Install Reason : Explicitly installed
>Install Script : Yes
>Validated By   : None
>root at eanna i ~ # modinfo kvm
>filename:       /lib/modules/3.18.6-1-ARCH/kernel/arch/x86/kvm/kvm.ko.gz
>license:        GPL
>author:         Qumranet
>intree:         Y
>vermagic:       3.18.6-1-ARCH SMP preempt mod_unload modversions
>parm:           ignore_msrs:bool
>parm:           min_timer_period_us:uint
>parm:           tsc_tolerance_ppm:uint
>parm:           allow_unsafe_assigned_interrupts:Enable device
>assignment on platforms without interrupt remapping support. (bool)
>root at eanna i ~ # grep -P "^(?\!#).*GRUB_CMDLINE" /etc/default/grub
>GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_osi=Linux iommu=pt iommu=1
>On Wed, Mar 25, 2015 at 9:53 AM, G. Richard Bellamy
><rbellamy at pteradigm.com> wrote:
>> I've been having intermittent network issues on my Host - they go away when
>> I stop and disable libvirtd and then reboot. They do not go away if I just
>> stop libvirtd and don't reboot.
>> I'm at a loss as to where to start with my troubleshooting, and being a
>> relative n00b to libvirt, I'd love any pointers.
>libvirt-users mailing list
>libvirt-users at redhat.com
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