Hi Mario,

Can you check the offload settings of the tap device that is connected to guest?

Run “ethtool -k tap-solaripub”.

On the guest. Raise the log verbosity by going to device manager -> NetKVM 
device -> Advanced tab -> Logging.Level and changing it to 4. Use DebugView to 
record the driver tracing (enable kernel trace): 
http://technet.microsoft.com/en-us/sysinternals/bb896647.aspx


Best regards,
Yan.


On Nov 22, 2013, at 7:28 PM, Mario De Chenno <c...@dechenno.eu> wrote:

> Hi all.
> We are facing some network issues on some Windows Server 2003 machines.
> In short, network seems to lock up and stops responding even to ping 
> requests. From TCPdump on the tap interface on the server I only see arp 
> request to the gateway, without replies. Increased tx overruns on the some 
> interface too. No errors at all on windows side. Most of the time we can 
> disable the interface from within windows and re-enable it to make things 
> work again. Rarely we have to shut down the virtual machine (Windows reboot 
> does not solve the problem).
> The issue appears randomly without apparent relation with server activity. 
> One server makes a lot of small outbond connections and locks up about every 
> 12-24 hours. It has two nic defined and only one is affected (the heaviest 
> loaded). Other servers have just one nic and lock less often.
> We run Qemu-kvm 1.4.0 and latest virtio-win drivers. On the same host we did 
> run a Linux web server with no issue in months of activity, with traffic 
> peaks up to 80Mb/s.
> 
> Here's is the startup command:
> 
> qemu-system-x86_64 -enable-kvm -machine type=pc,accel=kvm -cpu kvm64 -pidfile 
> /vmstore/vm_pids/solari.pid -rtc base=localtime -drive 
> file=/vmstore/vm_disks/solari.img,if=virtio -netdev 
> tap,id=nic01,ifname=tap-solaripub,script=pub102-ifup -device 
> virtio-net-pci,netdev=nic01,mac=CE:DA:01:00:17:16 -netdev 
> tap,id=nic02,ifname=tap-solariconsip,script=consip-ifup -device 
> virtio-net-pci,netdev=nic02,mac=CE:DA:01:00:16:16 -vnc :16 -m 4096 -boot c -k 
> it -usbdevice tablet -name solari -daemonize
> 
> We tried also the following options without result
> ,vhost=off,vnet_hdr=on
> ,ioeventfd=on,event_idx=off
> 
> 
> How can we troubleshoot the issue?
> Thanks
> 

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