FBSD 6.2 Xeon 2.4ghz CPU and high load

Chuck Swiger cswiger at mac.com
Fri May 9 17:37:46 UTC 2008

On May 9, 2008, at 8:54 AM, DAve wrote:
> 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.

You should look more into the status of the various processes, and how  
long it takes your mail scanning to process a message compared to  
previously.  It might be the case that the config under 6.2 is  
allowing more instances to run at once and is just barely nudging the  
system into excessive paging.  Once that happens, performance drops  
and the system load increases significantly.

Do a couple of "ps aux | head -20" every 5 minutes or so, and put that  
data somewhere on a website, the process states will help give a  
better picture of what's going on.

[ ... ]
> 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.

It might be reasonable to try hyperthreading enabled, as your type of  
load might be improved by it on....


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