CPU Utilization on IBM x3755

[Won De Erick]

>First and foremost, I'm not sure why you cross-posted this on 3 separate
>lists (testing, performance, and hardware).  You probably should have
>posted this on freebsd-questions, and if no response after a week or so,
>again on freebsd-stable (although you're using FreeBSD 6.2).

>It's generally shunned by the FreeBSD mailing list community to
>cross-post to so many lists.  Just something to keep in mind for the
>future.

Thanks for this reminder. I am testing my hardware against FreeBSD, and I just want to reach those people under the said areas (testing, performance, hardware) with the hope to get speedy response. 

>> Then what should I use? I am interested in getting the detailed info to justify the %CPU idles and utilization.

>Of the entire machine?  You can see that in top's header:

>last pid: 84636;  load averages:  0.47,  0.14,  0.04 up 79+01:15:18  04:46:01
>75 processes:  2 running, 70 sleeping, 3 stopped
>CPU: 28.6% user,  0.0% nice,  8.2% system,  0.0% interrupt, 63.3% idle
>Mem: 207M Active, 2433M Inact, 212M Wired, 91M Cache, 112M Buf, 57M Free
>Swap: 8192M Total, 228K Used, 8192M Free

>Regarding why you're adding up all the individual process statistics: I
>can imagine they would vary a slight bit, but I cannot explain a 7%
>variance.  Someone with more knowledge will have to assist there.

Though the header could be conclusive, I should want the specific processes (or threads). 
And come up with a list of breakdowns, like:

User (28.6%)
1. Program1 -- 20.0%
2. Program2 --  8.6%

System(8.2%)
1. SystemProcess1 -- X %
2. (and so on)         -- Y %

Then match this by adding up all individual processes statistics. And if I couldn't match, at least I could tell some factors that cause variance.
This variance has really struck my attention. When I run "top -SI", the result was:


last pid:  2746;  load averages:  0.20,  0.16,  0.10 up 0+00:07:38  
15:54:26
125 processes: 12 running, 100 sleeping, 16 waiting
CPU states:  
0.3% user,  0.0% nice,  6.4% system,  0.0% interrupt, 93.2% idle
Mem: 42M 
Active, 18M Inact, 62M Wired, 20M Buf, 27G Free
Swap:
 
  PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU 
COMMAND
   17 root        1 171   52     0K    16K RUN    0   6:05 99.02% 
idle: cpu0
   15 root        1 171   52     0K    16K CPU2   2   6:05 99.02% 
idle: cpu2
   14 root        1 171   52     0K    16K CPU3   3   6:28 96.58% 
idle: cpu3
   10 root        1 171   52     0K    16K CPU7   7   6:19 92.24% 
idle: cpu7
   11 root        1 171   52     0K    16K CPU6   6   6:22 92.09% 
idle: cpu6
   16 root        1 171   52     0K    16K CPU1   1   6:30 91.26% 
idle: cpu1
   12 root        1 171   52     0K    16K CPU5   5   6:26 84.47% 
idle: cpu5
   13 root        1 171   52     0K    16K CPU4   4   6:36 83.50% 
idle: cpu4

The header says 12, but there were only 8 processes displayed. Sometimes it goes down to 10, but not 8.
Hope you can shed me more lights on this.