Xen users - Nov 2006 - Network performance problem with Xen 3.0.3 HVM/VT

Hi,

I know it''s a problem that has already been discussed, but as I
didn''t see any
solution, I''m asking...

We''ve been trying to use Xen 3.0.3 HVM mode with windows or linux in
the past
few weeks, and have been suffering from bad network performance.
First, I must say that we didn''t succed to setup Windows 2000/2003
directly
using  Xen, we had to install it using qemu and then boot it into Xen HVM.

The performance problem seems to be coming from network latency :
depending on the host OS, we have measured ping times ranging from 4ms 
(Windows 2000, Linux) to 10ms (Windows 2003). Of course, the network 
performance is suffering, with throughputs aroud 600kbytes/s for Windows 
2003, and 3Mbytes for Windows 2000 and Linux.
The CPUs are idle during our benchmarks.


We suspected the network driver was using some kind of polling, because there 
is no load, and the latency is that big. We tried to compare with latest 
qemu, and qemu hasn''t displayed this latency problem.

Does anybody know of this problem ? (a solution, workaroud, patch, would be 
even better of course :) ).

This is a very big performance issue (for us), and we are reluctantly thinking 
about going back to vmware.

Any help would be welcome

Details about our setup :
- This is using DELL PE2950 with woodcrest CPUs.
- We use PAE build from Xen 3.0.3 sources
- Configuration file :
kernel = ''/usr/lib/xen/boot/hvmloader''
builder=''hvm''
memory = 512
name = "xxxxx"
vcpus=1
acpi=0
apic=0
pae=0
vif = [ ''type=ioemu, mac=aa:00:00:e7:00:02, bridge=x-brxxxx'']
disk = 
[ ''phy:/dev/drbd2,ioemu:hda,w'',
''file:/mnt/iso/windows2003p.iso,hdc:cdrom,r'' ]
on_poweroff = ''destroy''
on_reboot    = ''restart''
on_crash     = ''restart''
device_model = ''/usr/lib/xen/bin/qemu-dm''
boot="c"
sdl=0
vnc=1
vncviewer=0
nographic=0
ne2000=0
usb=1
usbdevice=''tablet''
audio=0

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