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[rhelv5-list] RHEL5 KQEMU Bridge network performance problem



I have a serious bridge network performance problem with a KQEMU
installation. I am trying to run multiple VM's all with their own ip
address, mac and hostname on the LAN. The hostnames, mac's and ip's are
all defined on a dns-server so no problems there. The machine, using root
initially, is running RHEL5 64bit, ip forwarding enabled, a relaxed
firewall (no rules just forwarding for testing), enough disk space and ram
for the VM's and I have used bridge utilities to build a bridge br0 using
the script below:

Versions:
qemu 0.9.0 (from source)
kqemu 1.3.0pre11 (from source)
kernel 2.6.18-8.1.8.el5 SMP 2 x apparent CPU due to HT enable, no VT

#!/bin/sh

# Setup the bridge
brctl addbr br0
# Add host ethernet adapter to the bridge
brctl addif br0 eth0
# Remove IP address from host ethernet device
ifconfig eth0 0.0.0.0 up
# Grab an IP address from DHCP for the bridge
dhclient br0
# Add the kqemu module
modprobe kqemu

I have disk images with RHEL 5 32bit machines and launch them using this
script:

#!/bin/bash
/usr/local/bin/qemu-system-x86_64 -kernel-kqemu -cdrom images/boot.iso \
-boot c -net nic,vlan=0 -localtime -m 512m \
-net tap,vlan=0,ifname=tap0,script=/etc/kqemu/qemu-ifup images/vdisk01.img

Notice I do not define the host mac address. The bridge works without
defining the mac, if I do, i.e.

#!/bin/bash
/usr/local/bin/qemu-system-x86_64 -kernel-kqemu -cdrom images/boot.iso \
-boot d -net nic,vlan=0,macaddr=23:23:23:00:00:01 -localtime -m 512m\
-net tap,vlan=0,ifname=tap0,script=/etc/kqemu/qemu-ifup images/vdisk01.img

the tap0 device does bind but bridging simply does not work, ping from the
host to the VM returns nothing.

The script to bind is:

#!/bin/bash

BRIF=br0
echo "Connecting interface $1 to bridge $BRIF"
/sbin/ifconfig $1 0.0.0.0 promisc up
/usr/sbin/brctl addif $BRIF $1

So the bridge does work but with no predefined mac for the host which I do
*need*.

The bridge network performance issue when I have one or more VM's running
is slow network speed and erratic latency, lost packets on commence of ping
from another host on the LAN, i.e. my laptop or another machine and from
the host itself where the ping responses are slightly better but I still
loose packets.

Has anyone a similar setup and managed to bind tap$ with a predefined mac
and have the bridge work and also has good quality bridge speed / network
preformance?


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