[Qemu-devel] qemu-kvm guest network stalls

[William King]

I have an ubuntu lucid host and an ubuntu lucid guest. Under heavy
network load the guest network stalls and is only able to come back
after running "sudo /etc/init.d/networking restart" on the guest.

Here are some (hopefully) helpful details.
------------------------------------Host---------------------------

# uname -a
Linux virtserv 2.6.32-22-server #36-Ubuntu SMP Thu Jun 3 20:38:33 UTC
2010 x86_64 GNU/Linux

# ifconfig -v
br0       Link encap:Ethernet  HWaddr 00:e0:4d:20:1f:86
          inet addr:192.168.100.145  Bcast:192.168.100.255
Mask:255.255.255.0
          inet6 addr: fe80::2e0:4dff:fe20:1f86/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1254011 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1070096 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:439139185 (439.1 MB)  TX bytes:836663432 (836.6 MB)

eth0      Link encap:Ethernet  HWaddr 00:e0:4d:20:1f:86
          inet6 addr: fe80::2e0:4dff:fe20:1f86/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:124712767 errors:0 dropped:0 overruns:0 frame:0
          TX packets:91086029 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:162562714983 (162.5 GB)  TX bytes:36005498601 (36.0 GB)
          Interrupt:29 Base address:0x8000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:83577 errors:0 dropped:0 overruns:0 frame:0
          TX packets:83577 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:15722576 (15.7 MB)  TX bytes:15722576 (15.7 MB)

virbr0    Link encap:Ethernet  HWaddr 5a:f3:dc:99:84:ee
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          inet6 addr: fe80::58f3:dcff:fe99:84ee/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:468 (468.0 B)

vnet0     Link encap:Ethernet  HWaddr ca:8b:d8:66:e6:f5
          inet6 addr: fe80::c88b:d8ff:fe66:e6f5/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:81138964 errors:0 dropped:0 overruns:0 frame:0
          TX packets:111911797 errors:0 dropped:0 overruns:100 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:31177137669 (31.1 GB)  TX bytes:147190153358 (147.1 GB)

# dpkg -l |grep qemu
ii  kvm
1:84+dfsg-0ubuntu16+0.12.4+noroms+0ubuntu3~ppa1 dummy transitional
pacakge from kvm to qemu-kvm
ii  qemu-common
0.12.4+noroms-0ubuntu3~ppa1                     qemu common
functionality (bios, documentation, etc)
ii  qemu-kvm
0.12.4+noroms-0ubuntu3~ppa1                     Full virtualization on
i386 and amd64 hardware


I installed the 0.12.4 qemu-kvm package that was built for lucid and
uploaded here:
https://edge.launchpad.net/~ubuntu-virt/+archive/ppa/+packages

# cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

auto br0
iface br0 inet dhcp
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0



------------------------------Guest-------------------------------
uname -a
Linux torrents 2.6.32-22-server #36-Ubuntu SMP Thu Jun 3 20:38:33 UTC
2010 x86_64 GNU/Linux

# ifconfig -v
eth0      Link encap:Ethernet  HWaddr 52:54:00:1e:6e:b4
          inet addr:192.168.100.203  Bcast:192.168.100.255
Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe1e:6eb4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:39410626 errors:0 dropped:0 overruns:0 frame:0
          TX packets:28376412 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:52260862769 (52.2 GB)  TX bytes:10005355703 (10.0 GB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:14096 errors:0 dropped:0 overruns:0 frame:0
          TX packets:14096 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:67362075 (67.3 MB)  TX bytes:67362075 (67.3 MB)

# cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp





Notes:
The TX and RX amounts are different from guest to host because I have
restarted the guest 'recently'.
One interesting thing I found was that the command 'arp -an' returns
nothing on the guest while it is stalled.

On 0.12.3 I was getting network stalls every 1-3 minutes with out fail.
After upgrading to 0.12.4 I still get the stalls mostly every 1-5
minutes but some times it lasts over an hour between stalls.

-William King