Bad internet performance for Host to Guest or Guest to Host

[max]

Hi,
Internet performance for Host to Quest is low.
The speed Guest to same Guest is 11.3 Gbits/sec
The speed Host to same Host is similar (9.8-11 Gbits/sec)

But the speed from Guest to Host is slow and around 1Gbit/sec.
In the reality traffic never leave a Host. I expected that in this case speed should be close to Host to Host.
It is important for virtual infrastructure when you have several Guests on a same Host. Guest to Guest on a same host has speed around 1 Gbits/sec too.

Below you can find testes and additional information:

=========================================================================
biouml@biouml-db:~$ iperf -c 192.168.2.31 -t 30 #Guest to Guest
------------------------------------------------------------
Client connecting to 192.168.2.31, TCP port 5001
TCP window size: 49.7 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.2.31 port 52170 connected with 192.168.2.31 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-30.0 sec 39.6 GBytes 11.3 Gbits/sec
============================================================================
biouml@biouml-db:~$ iperf -c 192.168.2.11 -t 30 # Guest to Host
------------------------------------------------------------
Client connecting to 192.168.2.11, TCP port 5001
TCP window size: 43.4 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.2.31 port 47148 connected with 192.168.2.11 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-30.0 sec 3.69 GBytes 1.06 Gbits/sec
biouml@biouml-db:~$
============================================================================
root@s2-8core:~# iperf -c 192.168.2.30 -t 30 #host to guest
------------------------------------------------------------
Client connecting to 192.168.2.30, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.2.11 port 57403 connected with 192.168.2.30 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-30.0 sec 5.47 GBytes 1.57 Gbits/sec

==========================================================================
root@s2-8core:~# iperf -c 192.168.2.11 -t 30 #host to host
------------------------------------------------------------
Client connecting to 192.168.2.11, TCP port 5001
TCP window size: 49.7 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.2.11 port 38313 connected with 192.168.2.11 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-30.0 sec 34.5 GBytes 9.87 Gbits/sec
root@s2-8core:~#
========================================================================

I am using virtio drivers and virtual machine was started with following parameters:

/usr/bin/kvm -S -M pc-1.0 -enable-kvm -m 4096 -smp 4,sockets=4,cores=1,threads=1 -name one-25 -uuid d1e125ee-d692-4598-3a75-441cd79a513a -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/one-25.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -drive file=/var/lib/one/OpenNebula/var//25/images/disk.0,if=none,id=drive-virtio-disk0,format=raw,cache=none -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive file=/var/lib/one/OpenNebula/var//25/images/disk.1,if=none,id=drive-virtio-disk3,format=raw -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk3,id=virtio-disk3 -netdev tap,fd=19,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=02:00:c0:a8:02:02,bus=pci.0,addr=0x3 -usb -device usb-mouse,id=input0 -vnc 0.0.0.0:98 -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6
=============================================================================
Qemu version:
root@s2-8core:~# /usr/bin/kvm --version
QEMU emulator version 0.15.92, Copyright (c) 2003-2008 Fabrice Bellard

root@s2-8core:~# ls -la /usr/bin/kvm
lrwxrwxrwx 1 root root 27 2011-11-07 17:34 /usr/bin/kvm -> /usr/bin/qemu-system-x86_64

==========================================================================
Bridge configuration:

root@s2-8core:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto eth1
iface eth1 inet manual

auto br0
iface br0 inet static
        address 192.168.2.11
        network 192.168.2.0
        netmask 255.255.255.0
        broadcast 192.168.2.255
        gateway 192.168.2.1
        bridge_ports eth0
        bridge_stp on
        bridge_fd 0
        bridge_maxwait 0
root@s2-8core:~#

root@s2-8core:~# brctl show
bridge name bridge id STP enabled interfaces
br0 8000.001e8cec6113 yes eth0
       vnet0
virbr0 8000.000000000000 yes

root@s2-8core:~# brctl --version
bridge-utils, 1.5
===============================================================
root@s2-8core:~# uname -a
Linux s2-8core 3.0.0-13-server #22-Ubuntu SMP Wed Nov 2 15:09:08 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

[Thomas Huth (th-huth)]

Triaging old bug tickets ... can you still reproduce this problem with the latest version of QEMU (currently v2.9.0)?

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]