[Bridge] Slow receive side on bridge

[<james.card@nokia.com>]

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Hi,

I have a CentOS 5.4 distro running Xen on top of a Linux bridge (set up by Xen).  I have noticed by using iPerf in bidirectional mode that the traffic going into the server running the bridge is quite a bit slower with the bridge enabled than when it isn't.   The HW is a multiblade setup (8 blades each running CentOS 5.x).  On one of the blades, I shut down Xen and initially run with the bridge shut down and transferred a file from another machine using scp.  I then started up the bridge and transferred the same file and you can see below there is a big difference (3.6MB/s vs 23.2KB/s).  I stopped Xen before doing the following...

Any help on where to look would be helpful.  I was going to shut down all but one blade to see if it could be a lack of STP causing issues.

-- Xen bridge initially shut down

[root@bsbchp003 ~]# brctl show
bridge name    bridge id        STP enabled    interfaces
virbr0        8000.000000000000    yes

-- transfer the 3.7GB file

[root@bsbchp003 ~]# scp card@harvard:bigfile .
bigfile                                                                                                                                                                 100% 3685KB   3.6MB/s   00:00

-- start the bridge

[root@bsbchp003 ~]# /etc/xen/scripts/network-bridge start
net.bridge.bridge-nf-call-arptables = 0
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
Nothing to flush.
Nothing to flush.
Waiting for peth0 to negotiate link..[root@bsbchp003 ~]#

-- the Xen bridge is now up

[root@bsbchp003 ~]# brctl show
bridge name    bridge id        STP enabled    interfaces
virbr0        8000.000000000000    yes
xenbr0        8000.feffffffffff    no        peth0
                            vif0.0
[root@bsbchp003 ~]# scp card@harvard:bigfile .
bigfile                                                                                                                                                                 100% 3685KB  23.2KB/s   02:39
[root@bsbchp003 ~]#

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