Indeed, I managed to get very good results after I disabled TSO on the gre_sys interface. As a curiosity, disabling all 3 (TSO, GSO and GRO) on gre_sys interface returned good performance but half the best performance (obtained when only TSO is off). FYI: LRO was off by default for me.
Thanks everybody ! > On Jul 5, 2016, at 4:45 PM, Alexander Duyck <alexander.du...@gmail.com> wrote: > > On Mon, Jul 4, 2016 at 1:34 PM, D3c3 Balus <d3c3ba...@gmail.com> wrote: >> Hello, >> >> I’m using 2 Ubuntu Xenial 16.04 LTS with the following: >> - kernel: 4.4.0-28-generic >> - OVS version: 2.5.0 (installed from ubuntu packages: openvswitch-common & >> openvswitch-switch) >> >> I’m configuring a GRE tunnel between OVS bridges running on each of the >> machines with: >> >> ovs-vsctl add-port br0 tun0 -- set Interface tun0 type=gre >> options:remote_ip=x.x.x.x >> >> and I achieve connectivity between VMs, as desired, via the GRE tunnel. >> >> >> Problem: iperf test show really low performance (734 bits/sec !!) >> considering a baseline that shows almost 1G over the direct link. >> >> Troubleshooting performed: >> 1. increased MTU of the physical link on both sides: `ip link set dev enp0s8 >> mtu 2000` => same poor perf >> 2. increased MTU of the br0 on both OVS bridges: `ip link set dev br0 mtu >> 1700` => same poor perf >> >> [FYI: I performed the same operations on an older version of Ubuntu = >> Trusty 14.04 LTS, kernel 3.13.0-86, and after adjusting the MTU as above, >> the GRE performance was satisfactory ~ 414 Mbps !! ] > > One data point that would be really useful would be what physical > links are you using, specifically what driver and device combination. > More often then not these type of issues are due to something like LRO > or GRO creating an oversized frame, or the TSO feature advertising > support for a tunnel it doesn't actually support. You might go > through and verify if any of these features are enabled on the > physical link using "ethtool -k" and then go through and disable them > until you see the performance improve. > > Hope that helps. > > - Alex _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
