CPU Utilization on IBM x3755

Won De Erick won.derick at yahoo.com
Sun Aug 17 08:36:18 UTC 2008

On Sat, Aug 16, 2008 at 01:18:18AM -0700, Won De Erick wrote:

>> >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:
>> 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.
>At the bottom of man top, reformatted for email width:
>    As with ps(1), things can change while top  is  collecting
>    information for  an  update.  The picture it gives is only
>    a close approximation to reality.
>Could this explain the variations you are seeing? top never gives you
>an accurate snapshot of what the system is doing at any one instant in
>time, afaik.


I'm aware with this limitation as displayed using man top. But when I ran top -SI, I only got 8 processes out of 12 processes [actively] running as displayed on the header making it far from reality. I did this several times, restarting the machine, bootstrapping, etc, but I got same result.

I don't know what kernel threads are causing top -S to display the command as "idle: cpu0", "idle : cpu1", ... "idle:cpu7". Though Jeremy had mentioned them as simply kernel threads (due to lack of term), I should at least dig deeper on this matter and be able to specifically classify them.


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