[PVE-User] Network performance issue

Martin n at 1e.ca
Sun Feb 12 12:28:31 CET 2012


the issue I'm having may have to do with the guest kernel more than
proxmox, but here it goes:
Host is proxmox 1.9, network eth0: RTL8168c/8111c at 1Gbps.
Guest is Ubuntu 11.10, kernel 3.0.0-15.
>From my 100Mbps cable service with tcp ack suppression (in the
provider-controlled modem firmware), approximately 17ms away:
virtio: one tcp stream tops at 25Mbps, I can full the pipe by adding
more connections
rtl8139: one tcp stream 100Mbps
I've read that this tcp ack suppression performance issue that started
with kernel 2.6.39 (from what I gathered) is more affected on gigabit
networks, and indeed choosing a 100mbit driver fixes the bug, although
the available throughput from the guest is still gigabit (!).
So it is not an issue for me to run rtl8139 on the guest but I am
puzzled by this undocumented feature :) If anyone knows where to start
looking for a way to fix this, I'd be glad to help troubleshoot and
report it to the appropriate people.


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