FBSD 6.2 Xeon 2.4ghz CPU and high load

[DAve]

Good morning.

I recently upgraded our two email gateways from 4.8 to 6.2. The required 
software was upgraded as well which consists of MailScanner and 
Sendmail. Both had been keep up to date so it was not a jump in required 
resources.

The issue I am seeing is that my server load, under the same traffic 
load, has increased 4 times or more. Where previously we saw a high load 
on the servers of 5 to 8, we are now seeing 14 to 17. Since the upgrade 
Sendmail has begun to timeout connections.

I have been digging through the system, mail lists, forums, anything to 
help determine the cause of the increased load. Here are some examples 
of what I am seeing.

bash-2.05b# vmstat -w2
  procs      memory      page                    disks     faults      cpu
  r b w     avm    fre  flt  re  pi  po  fr  sr da0 da1   in   sy  cs us 
sy id
12 5 0 2234516 199864  772   4   0   4 431 447   0   0  485  564 927 29 
  4 67
11 6 0 2229788 181352 8631   0   0   0 5597   0   0   0  294 2592 1236 
45  5 50
  9 5 0 2227208 168144 6456   0   0   0 4607   0   2   0  278 1333 898 
46  4 50
11 5 0 2229068 175868 5164   0   0   0 5423   0   0   0  212  766 541 47 
  3 50
14 7 0 1948392 236296 8136   0   0   0 12382   0  14   0  368 4135 1504 
42  8 50
  4 3 2 1744620 321024 7550   0   0   0 13454   0  23   6  752 11417 
3919 42  8 50
12 5 0 1951788 258944 12490   0   0   0 11295   0   0   5  727 18566 
4844 40 10 50
16 6 0 2155668 214324 8231   0   0   0 4230   0   1  29  724 15531 4381 
41  9 50
  8 6 1 2044828 242084 4567   0   0   0 9119   0   0  12  774 12196 3225 
43  7 50


bash-2.05b# top
last pid: 85205;  load averages: 12.89, 13.78, 14.66 
                                                              up 
47+15:51:31  15:20:01
126 processes: 12 running, 79 sleeping, 35 zombie
CPU states: 43.8% user,  0.0% nice,  6.3% system,  0.0% interrupt, 50.0% 
idle
Mem: 1008M Active, 582M Inact, 211M Wired, 78M Cache, 112M Buf, 122M Free
Swap: 4096M Total, 304M Used, 3792M Free, 7% Inuse

I am suspicious of the kernel being the culprit because the system looks 
as if it is not working very hard, CPU load never shows above 50% idle. 
I found one thread which mentions that as an issue and offers a patch.

http://lists.freebsd.org/pipermail/freebsd-bugs/2007-February/022526.html

Currently I am running the SMP-GENERIC kernel and sysctl shows the 
following.

hw.model: Intel(R) Xeon(TM) CPU 2.40GHz
machdep.hlt_logical_cpus: 0
machdep.hyperthreading_allowed: 0
kern.smp.cpus: 4
I see dev.cpu.0 through dev.cpu.3

Can anyone offer a solution? Is this a known issue I can easily correct? 
At this point I am left with either rolling back to 4.11 or trying 
another OS.

I am thinking I have missed something obvious and I need to make a 
sysctl change to get the system working properly. Any help is 
appreciated, I'm losing mail.

Thanks,

Dave

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