requests for mbufs denied?

Michael Butler imb at
Mon May 22 06:44:41 PDT 2006

On a 6-stable machine with sufficient RAM, i.e. no swapping and 215MB 
free in 'top', I'm seeing ..

imb at sarah:/home/imb# netstat -m
386/529/915 mbufs in use (current/cache/total)
384/254/638/17088 mbuf clusters in use (current/cache/total/max)
384/128 mbuf+clusters out of packet secondary zone in use (current/cache)
0/0/0/0 4k (page size) jumbo clusters in use (current/cache/total/max)
0/0/0/0 9k jumbo clusters in use (current/cache/total/max)
0/0/0/0 16k jumbo clusters in use (current/cache/total/max)
864K/640K/1504K bytes allocated to network (current/cache/total)
1405/14/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters)
0/0/0 requests for jumbo clusters denied (4k/9k/16k)
0/6/4528 sfbufs in use (current/peak/max)
0 requests for sfbufs denied
0 requests for sfbufs delayed
0 requests for I/O initiated by sendfile
28 calls to protocol drain routines

What prompts this behaviour? Do I want/need to "play with" any sysctls 
to preallocate more space?

Michael Butler, CISSP
Security Architect
Protected Networks

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