strange igb interface performance problems

[Mario Spinthiras]

Hello All,

 The subject topic might catch a few by surprise because for the most part
it smells a lot like a problem that came to light in 2009 regarding bad
performance on Intel NICs using the igb driver.

 I currently have a point to point link between 2 pfsense 2.0RC1 running
FreeBSD 8.1 that connect via a 1Gbps link. The link itself has been tested
and the provider reckons that the link is fine. (I also believe this too).

We then started high and went low to search for the problem. We ditched out
the media converters, went on a mad mission to tune every single last detail
on the stack to give us the full performance, however on the 1Gbps line we
see a rough 20Mbps.

We then turned towards the igb driver which smells a little funny
considering that the issues I mentioned that have emerged back in 2009
regarding similar issues are alive and well today.

Does anyone out there have any experience or knowledge of such problems
caused by the igb driver? I'm going to plan a maintenance window on this
link within the next day or so hoping that I'll be able to live boot a 2.0
RC1 nightly and try it again. The current RC1 is one of the earlier ones.

Any info you can send my way on this baffling mystery that has taken me on a
goose chase. Disabling TSO/LRO does not solve the problem for me. Can anyone
shed some light on this?


Thanking you all in advance,

Mario