%cpu usage exceed 100?

Posted on 2003-03-06
Medium Priority
Last Modified: 2012-05-04

Is it possible that the  %of cpu usage shown by top command, when added up may exceed 100?

Question by:cdajay
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Accepted Solution

chris_calabrese earned 100 total points
ID: 8080937

Top shows the percentage of _one_ cpu that each process is using on average.

If your system has more than one cpu, the total available cycles are N * 100%, where N is the number of cpu's.

In fact, a single process can even use more than 100% of one cpu if it's a multi-threaded process on a multi-processor machine.

Expert Comment

ID: 8086830

This is depends on Unix system, but it may yes.

Others will show this as 100% is all cpus in machine.

/Hans - Erik Skyttberg

Assisted Solution

nricioppo earned 100 total points
ID: 8153000
The answer is yes, it IS possible.

Taken directly from the manual entry for "top" in Redhat Linux 7.3

"CPU states
     Shows the percentage of CPU time in user mode, system
     mode,  niced  tasks, and idle.  (Niced tasks are only
     those whose nice value is negative.)  Time  spent  in
     niced  tasks  will also be counted in system and user
     time, so the total will be more than 100%.  The  pro-
     cesses  and  states  display  may be toggled by the t
     interactive command."


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