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[Xen-users] Question regarding dropped packets


I've got a machine that's hosting a number of virtual machines (58 + the dom0) and I'm having some weird issues with packet loss and high latency that happens when ksoftirqd spikes in CPU usage.

The machine itself is CentOS 5 x86_64 running the stock Xen packages (3.1.2). It's a dual quad-core w/ hyperthreading, 48 gigs of ram, and using Adaptec hardware raid w/ SAS drives.

Almost every 2 minutes, I'll lose between 2 and 4 packets (while running ping) to the domUs and see a couple of packets with very high latency. I see the packets coming in on eth0, the bridge, and sometimes on the vif device but the domU itself doesn't see these packets.

Has anyone seen this type of behaviour before? I've tried all the following with little success:

    - increasing txqueuelen
    - changing the smp_affinity settings for our network devces
- dedicating the first 2 cores to dom0 and letting the domUs use the remaining 14.

If anyone has any ideas or additional things I can try, I would be most grateful :)


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