MBuf clusters - what uses them?

[Paul Goyette <paul%whooppee.com@localhost>]

I still have occassional lock-ups on my system which appear to be a 
result of MBuf Cluster exhaustion.  Just looking at netstat output, it 
shows that network is using about 554.  Yet vmstat -m shows more than 
1000 in use.

# netstat -m
553 mbufs in use:
        541 mbufs allocated to data
        11 mbufs allocated to packet headers
        1 mbufs allocated to socket names and addresses
98 calls to protocol drain routines
# vmstat -mW | grep '^[MNm]'
Memory resource pool statistics
Name              Size    Requests Fail    Releases  InUse Avail  Pgreq  Pgrel 
Npage PageSz Hiwat Minpg Maxpg Idle Flags   Util
mbpl               512       32661    0       31465   1196    44    391    236  
 155   4096   287     2   inf    3 0x000  96.5%
mclpl             2048       27746    0       26731   1015     9   1644   1132  
 512   4096   865     4 524274   4 0x000  99.1%
mutex               64     4642962    0     2951894 1691068 604715 36471    30 
36441   4096 36471     0   inf    1 0x040  72.5%
#


So, what is using the additional ~450 MBuf Clusters?


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