amd64/168342: mbuf exhaustion hangs all daemons in keglimit state

[Ziyan Maraikar]

Hello John,

Thanks for the response.
> 
> Have you tried increasing kern.ipc.nmbclusters?  Alternatively, have you tried 
> restricting igb to only using 1 queue?  It sounds like all your igb interfaces 
> are allocating all of your mbuf clusters for their receive rings.
> 
I found this very suggestion on several mailing list discussions [1] and set these values on Saturday.
kern.ipc.nmbclusters="131072"
hw.igb.num_queues="2"
So far everything seems to back to normal, and netstat -m shows plenty of headroom now. 

The problem cropped up after running several months on 9.0-RELEASE when I  brought up another interface. Disabling the new interface didn't restore normal operation, however. I also tried 8.3-RELEASE but the problem was worse on it.

[1] http://osdir.com/ml/freebsd-stable/2012-02/msg00563.html
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Regards
Ziyan.