802.3ad use one NIC on the way out

[Gary Griffith]

When we use the 3.16 kernel (Ubuntu 14.04.2) and have all our NIC pairs bonded using "bond-xmit-hash-policy layer3+4", I can run iperf with multiple threads and get 2Gbps throughput out of 2 x 1Gb NICs.

We then upgrade and run kernel 4.4.0 (Ubuntu 14.04.5) and notice on the SENDING side of iperf, I can only get one NIC to move traffic. It does seem to be isolated to the machine originating traffic being kernel rev 4.4.0, as I can run a 3.16 iperf SENDER pointed at a 4.4.0 iperf RECEIVER and get my 2Gbps. So - the problem is only evident on the iperf SENDING machine when it runs the 4.4.0 kernel.

The status of this particular Bugzilla report at https://bugzilla.kernel.org/show_bug.cgi?id=53321 bug is "Reopened". Somewhere between 3.16 and 4.4 - did bonding lose the ability to use multiple slaves when sending multiple transmissions?