Hello everybody,
this is my first post on a mailing list, so i hope everything works fine.

My host is a AMD X2 4850e with a 64bit Gentoo (unstable). I have tested 
qemu-kvm 0.11, 0.12.x and the git version from the 6. jan.
I created my own bridges, so i dont need the option from libvirt. I 
bridged a 1 Gb lan card for my VMs. When I use the virtio net driver,
i get something about 200-300 mbit form my desktop to one if my VMs. If 
iI use the e1000 driver instead of the virtio I get about
500 - 600 mbit.
I tested this with the following kernels:
Host: 2.6.31.6, 2.6.32.1, 2.6.32.2
Guests: 2.6.26, 2.6.30, 2.6.32 (debian)
2.6.32 (gentoo)

Here is a default result, virtio vs. e1000:

iperf -c 192.168.0.3 -w 512k -l 512k
------------------------------------------------------------
Client connecting to 192.168.0.3, TCP port 5001
TCP window size:   256 KByte (WARNING: requested   512 KByte)
------------------------------------------------------------
[  3] local 192.168.0.2 port 52968 connected with 192.168.0.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec    438 MBytes    267 Mbits/sec


iperf -c 192.168.0.3 -w 512k -l 512k
------------------------------------------------------------
Client connecting to 192.168.0.3, TCP port 5001
TCP window size:   256 KByte (WARNING: requested   512 KByte)
------------------------------------------------------------
[  3] local 192.168.0.2 port 52995 connected with 192.168.0.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec    602 MBytes    505 Mbits/sec

Any ideas what this could be? I attach a dmesg output of my host.
Thx.

Ben