[Xen-users] Massive UDP and TCP packet loss

["Walter Cronen" <wcronen@xxxxxxx>]

Sorry for repost, there was an sending error with my first posting.
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Hi,


I'm trying to get Xen running on 2 different systems and have massive packet 
losts independ from the system I use!

This are the results from an UDP-Benchmark-Test from an Xen-Server to another 
one. As you make notice, the
sending packets have a lost rate from > 80% up to 99%. What the hell is going 
on? I have no ideas.

If I boot my 2 Xen-Servers with the normal kernel (without Xen) then all is 
running wonderfull and I have no packet lost! Therefore it must be a Xen 
problem!

NETIO - Network Throughput Benchmark, Version 1.23
UDP connection established.
Packet size  1k bytes:  11547 KByte/s (85%) Tx,  11460 KByte/s (0%) Rx.
Packet size  2k bytes:  11031 KByte/s (92%) Tx,  11501 KByte/s (0%) Rx.
Packet size  4k bytes:  9683 KByte/s (95%) Tx,  11677 KByte/s (0%) Rx.
Packet size  8k bytes:  9459 KByte/s (96%) Tx,  11692 KByte/s (0%) Rx.
Packet size 16k bytes:  5502 KByte/s (98%) Tx,  11694 KByte/s (0%) Rx.
Packet size 32k bytes:  111 KByte/s (99%) Tx,  11716 KByte/s (0%) Rx.
Done.

Here is what I tried:
I set "tx off" on ALL interfaces with the ethtool command, changed 
tx-queue-length, disabled all iptables/ebtables, set bridging
to "sethello 0" and "setfd 0" ... But nothing changes.
I used the default Xen which comes with Redhat 5.2 and tried different 
Redhat-Kernels, also the latest from 5.3
Also I tried different Xen version. First 2-3 different versions which come 
with Redhat 5.2 and its updates. Then
I tried version 3.3.0 and 3.3.1 from another repository

ALL this doesn't solve the packet losts. The only way is disable Xen and use 
the default kernel. So what's wrong? Any ideas?

My 2 test sytems are:
1.) Dual Xen system with Quadcore, 16gb ram, intel nic
2.) Normal Quadcore, 2gb ram, intel nic
Both system are running under Redhat 5.2 with latest updates.

Any help is greatly appreciated.

Thanks
Heiner
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