Thanks, Mike. I tried to reproduce this with two lucid machines. With both not using bridges, I got:
------------------------------------------------------------ Client connecting to 10.55.55.5, TCP port 5001 TCP window size: 166 KByte (default) ------------------------------------------------------------ [ 5] local 10.55.55.5 port 34214 connected with 10.55.55.5 port 5001 [ 4] local 10.55.55.5 port 5001 connected with 10.55.55.5 port 34214 [ ID] Interval Transfer Bandwidth [ 5] 0.0-10.0 sec 16.3 GBytes 14.0 Gbits/sec [ 4] 0.0-10.0 sec 16.3 GBytes 14.0 Gbits/sec root@mabolo:~# iperf -c 10.55.55.5 -d ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ ------------------------------------------------------------ Client connecting to 10.55.55.5, TCP port 5001 TCP window size: 199 KByte (default) ------------------------------------------------------------ [ 5] local 10.55.55.5 port 34215 connected with 10.55.55.5 port 5001 [ 4] local 10.55.55.5 port 5001 connected with 10.55.55.5 port 34215 [ ID] Interval Transfer Bandwidth [ 5] 0.0-10.0 sec 16.4 GBytes 14.1 Gbits/sec [ 4] 0.0-10.0 sec 16.4 GBytes 14.1 Gbits/sec With one having a bridge, I got: ------------------------------------------------------------ Client connecting to 10.55.55.5, TCP port 5001 TCP window size: 49.7 KByte (default) ------------------------------------------------------------ [ 3] local 10.55.55.5 port 34216 connected with 10.55.55.5 port 5001 [ 5] local 10.55.55.5 port 5001 connected with 10.55.55.5 port 34216 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 23.0 GBytes 19.7 Gbits/sec [ 5] 0.0-10.0 sec 23.0 GBytes 19.7 Gbits/sec root@mabolo:~# iperf -c 10.55.55.5 -d ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ ------------------------------------------------------------ Client connecting to 10.55.55.5, TCP port 5001 TCP window size: 49.7 KByte (default) ------------------------------------------------------------ [ 4] local 10.55.55.5 port 34217 connected with 10.55.55.5 port 5001 [ 5] local 10.55.55.5 port 5001 connected with 10.55.55.5 port 34217 [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.0 sec 23.2 GBytes 20.0 Gbits/sec [ 5] 0.0-10.0 sec 23.2 GBytes 20.0 Gbits/sec However, looking back at your results, look at the TCP window sizes. They are similar to mine in all but the degenerate case, where it is 1.25Mb. Could you show the values of the following files: /proc/sys/net/ipv4/tcp_rmem /proc/sys/net/ipv4/tcp_wmem on both hosts? -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to bridge-utils in Ubuntu. https://bugs.launchpad.net/bugs/894608 Title: Implementing a bridge slows 10G network To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bridge-utils/+bug/894608/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs