Checking mbuf cluster usage

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

Hello.

I just had a network hickup on our gateway, probably due to "mclpool limit 
reached; increase kern.mbuf.nmbclusters". I should probably monitor that, 
so I get warned before the limit is reached and the gateway stops functioning.

But how do I do that? netstat -m reports mbufs allocated, while 
kern.mbuf.nmbclusters is about, well, mbuf clusters. How do these values 
corelate?