Intel igb 82576 (netmap mode) and RSS queue issuse with fragmented UDP packets.

[Adrian Chadd]

oh, hm, you asked the next question. Sorry, I haven't had coffee.

I vaguely remember testing this and discovering the /should/ be
putting all the frames in a packet int he same queue, as long as the
frames have a consistent set of fragment bits set. Ie, if you're doing
UDP and all frames in a packet have the fragment bit set, then all
fragments (first and the rest) go into the same queue. Frames in a
flow that are fragmented for some and not others (eg TCP flows with a
firewall/router doing explicit fragmentation, or a mix of small/large
UDP packets) will end up going into different queues.

I can re-test this on ixgbe at some point, but IIRC that's how it behaved.

I don't have the RSS stuff done for chelsio, so I haven't done any
experiments just yet.

Now, I also remember that with the badly setup flowdirector code in
ixgbe it would mess that up, so the flowdir code was disabled in -HEAD
and I believe now in -10.



-adrian