kern/95030: Problem with "requests for mbufs denied"

[Valery Marchuk]

>Number:         95030
>Category:       kern
>Synopsis:       Problem with "requests for mbufs denied"
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Mar 28 09:00:27 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Valery Marchuk
>Release:        6.1-PRERELEASE
>Organization:
ArgoCom
>Environment:
FreeBSD vpn1.xxx.xxx 6.1-PRERELEASE FreeBSD 6.1-PRERELEASE #3: Thu Mar 23 11:54:35 EET 2006 root at vpn1.xxx.xxx: /usr/obj/usr/src/sys/vpn_kernel i386
>Description:
There is a problem with denied mbufs according to netstat output:

netstat -m
1825/1670/3495 mbufs in use (current/cache/total) 
1501/1305/2806/25600 mbuf clusters in use (current/cache/total/max) 
3501K/3027K/6529K bytes allocated to network (current/cache/total)
59555674/20385922/20390226 requests for mbufs denied (mbufs/clusters/mbuf+clusters)
0/5/6656 sfbufs in use (current/peak/max)
0 requests for sfbufs denied
0 requests for sfbufs delayed
0 requests for I/O initiated by sendfile
551 calls to protocol drain routines

There are 3 NICs, 2 - em`s (Intel 1Gb) and 1 - rl (D-Link 100Mb). I`ve found 2 descriptions of the same (I guess) problem in Google, with em NICs installed. 
CPU: Pentium D 2.8 GHz (SMP)
RAM: Hynix 1Gb*2
Additional data:

kern.maxdsiz="1073741824"
kern.dfldsiz="1073741824"
kern.maxssiz="134217728"

net.inet.ip.same_prefix_carp_only=1
kern.ipc.somaxconn=32768

Kernel options:
kern.ipc.maxsockets: 25600 
kern.ipc.nmbclusters: 25600 

Current system`s sockets state:
netstat -an | grep tcp | awk '{print $6}' | sort | uniq -c
   7 CLOSE_WAIT 
 136 ESTABLISHED
  12 FIN_WAIT_1 
  34 FIN_WAIT_2 
   6 LAST_ACK   
  12 LISTEN     
   1 SYN_SENT   
  18 TIME_WAIT  

netstat -i shows no errors.
Will appreciate any help.
>How-To-Repeat:
I could not reproduce this problem on other systems (different hardware) with the same kernel options.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: