ixgbe 2.1.7 can't disable LRO on 82599?

[Andrew Boyer]

Hello all,
I'm using the 2.1.7 version of ixgbe from -CURRENT, backported to FreeBSD 7.1.  With some fiddling it seems to work on both 82598 and 82599 controllers.

On 82598, 'ifconfig ix0 -lro' causes dev.ix.0.counters.rxr0.lro_queued and ...lro_flushed to stop incrementing, as expected.  There's also a significant throughput hit which would seem to indicate that it took effect.

However, it appears that LRO is always enabled on 82599.  'ifconfig ix0 -lro' removes the LRO flag from the port in ifconfig but the ...hw_lro_merge counter continues to increase.  The throughput reported by the iperf port is the same with or without LRO on.

Any advice?  Am I misinterpreting something?

Thanks,
  Andrew

P.S.  We need to disable LRO because we don't have Appropriate Byte Counting support and LRO causes TCP ACK havoc without it.

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Andrew Boyer	aboyer at averesystems.com