On 7/25/16 10:39 AM, Lennert Buytenhek wrote: > Hi! > > I am seeing pretty horrible TCP transmit performance (anywhere between > 1 and 10 Mb/s, on a 10 Gb/s interface) when traffic is sent out over a > route that involves MPLS labeling, and this seems to be due to an > interaction between MPLS and TSO/GSO that causes all segmentable TCP > frames that are MPLS-labeled to be dropped on egress. ... > But, loading mpls_gso doesn't change much -- skb_gso_segment() then > starts return -EINVAL instead, which is due to the > skb_network_protocol() call in skb_mac_gso_segment() returning zero. > And looking at skb_network_protocol(), I don't see how this is > supposed to work -- skb->protocol is 0 at this point, and there is no > way to figure out that what we are encapsulating is IP traffic, because > unlike what is the case with VLAN tags, MPLS labels aren't followed by > an inner ethertype that says what kind of traffic is in here, you have > to have explicit knowledge of the payload type for MPLS. > > Any ideas?
A quick update. I have a pretty good handle on the GSO changes for MPLS but I am still puzzled by a few things. Hopefully by end of week I can send out a patch series. Current performance comparison with my changes and a patch from Roopa: MPLS ==== root@kenny-jessie3:~# ip netns exec ns0 netperf -c -C -H 10.10.10.10 -l 10 -t TCP_STREAM MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.10.10.10 () port 0 AF_INET Recv Send Send Utilization Service Demand Socket Socket Message Elapsed Send Recv Send Recv Size Size Size Time Throughput local remote local remote bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB 87380 16384 16384 10.00 3510.26 48.11 48.11 4.491 4.491 non-MPLS ======== root@kenny-jessie3:~# ip netns exec ns0 netperf -c -C -H 172.16.21.22 -l 30 -t TCP_STREAM MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 172.16.21.22 () port 0 AF_INET Recv Send Send Utilization Service Demand Socket Socket Message Elapsed Send Recv Send Recv Size Size Size Time Throughput local remote local remote bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB 87380 16384 16384 30.00 9654.97 42.37 42.37 1.438 1.438
