[Pkg-xen-devel] dom0 kernel for xen 3.2

[Nikita V. Youshchenko]

> > I've read somewhere that 2.6.18-5-xen kernel from etch is not
> > compatible with xen 3-1, and won't boot with it.
> > Is that true?
>
> I don't think that's true.. a friend of mine installed debian xen 3.1.2
> two days ago (64bit version) and booted dom0 with 2.6.18-5-xen kernel.
>
> > What about xen 3.2 ?
>
> I think it should work, but I've not tried it yet.
>
> > I'm currently running several xen-based servers, and there are some
> > issues with those. I would like to check if situation is better with
> > later xen releases.
>
> Problems with what? :)

We have a domain that runs a desktop server: about 50 Xvnc processes
each running a KDE desktop, with 15-20 users connected using vncviewer
from thin clients at patricular time.
Sometimes (10-20 times a day) network connection to this domain freezes,
and user desktops freeze for 5-30 seconds (then unfreeze). This is harmless,
 but annoys users a lot.

Here is example tcpdump log for such an event. Tcpdump was executed inside the domain.
...
13:33:38.134818 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9272, length 64
13:33:38.134861 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9272, length 64
13:33:39.138863 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9273, length 64
13:33:39.138925 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9273, length 64
13:33:40.142855 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9274, length 64
13:33:41.146918 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9275, length 64
13:33:42.150870 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9276, length 64
13:33:43.154838 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9277, length 64
13:33:44.158854 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9278, length 64
13:33:45.158853 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9279, length 64
13:33:46.158828 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9280, length 64
13:33:47.158880 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9281, length 64
13:33:48.158845 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9282, length 64
13:33:49.158799 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9283, length 64
13:33:50.158898 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9284, length 64
13:33:51.158799 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9285, length 64
13:33:52.158758 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9286, length 64
13:33:53.158844 IP zigzag.lvknet > desktopvm: ICMP echo request, id 52019, seq 9287, length 64
13:33:54.010610 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9274, length 64
13:33:54.010619 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9275, length 64
13:33:54.010636 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9276, length 64
13:33:54.010640 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9277, length 64
13:33:54.010647 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9278, length 64
13:33:54.010660 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9279, length 64
13:33:54.010687 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9280, length 64
13:33:54.010698 IP desktopvm > zigzag.lvknet: ICMP echo reply, id 52019, seq 9281, length 64
...

In this trace, during freeze, incoming packets continue to arrive, but
outgoing are not sent.

On one of other traces, I've seen that packets are still both arrived and sent
by the domain, but are frozen on the bridge in dom0.

This looks like some misinteraction between netfront inside domain,
xen netfront<->netback transport, netback in dom0, and probably linux bridge.

Nikita