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Re: Dom0 bad network performance

Hi Greg,

Am 13.02.21 um 15:50 schrieb Greg Troxel:
   - For any network issues, I recommend doing "netstat -s" before and
     after a test, and then diffing the results, trying to understand the
     origin of all counter changes.   For example in your case, there
     probably shouldn't be any dropped packets.  So if that increments --
     or more importantly some other counter none of us have thought
     about -- that's interesting.

Seems like my original response did not pass the filter of the mailing list due to attachments.

I have now run the test iperf3 with 128K window size on localhost again with netstat -s (before/after comparison). The system was rebooted before each test run and I ran the tests directly on the VGA console to exclude influences via SSH. When comparing the two diffs, I noticed:

- "packets sent" with Xen is only a third of the value without Xen. Is this an indication that different packet sizes are being used here, i.e. under Xen the packet size is larger by default?

- "correct ACK header predictions" and "correct data packet header predictions" are many times higher without Xen than with Xen. Both parameters don't tell me much, but they sound like a high value would be beneficial here, i.e. another indication that something is wrong in the case with Xen?

Kind regards

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