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When I run the TOP command, a process shows 1208% cpu usage and the total CPU usr time is 81.7% with IRIX mode on. When I change to IRIX mode off, the process shows 99% cpu usage and the total user cpu time is 43%.

Any ideas what might be going on?

Update Could the VM be misconfigured so CPU usage is not reported correctly?

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3  
How many CPUs do you have? –  Gilles Jun 27 '11 at 22:53
    
4 on the vm, 16 on the host. –  Brig Jun 28 '11 at 19:00

1 Answer 1

Irix / Solaris Mode(man 1 top):

     <I> :Irix/Solaris_Mode_toggle
          When operating in  'Solaris  mode'  ('I'  toggled  Off),  a
          task's  cpu  usage  will  be divided by the total number of
          CPUs.  After issuing this command, you'll  be  informed  of
          the new state of this toggle.


...

      if 'Irix mode' is Off,  top  will  operate  in
      'Solaris  mode' where a task's cpu usage will be divided by the
      total number of CPUs.  You toggle 'Irix/Solaris' modes with the
      'I' interactive command

Let say N is the total number of CPUs. Then In Irix mode, %CPU is the CPU usage out of N * 100%. In Solaris mode,%CPU is the%CPU in Irix mode / N.

See: Comprehending 'top' CPU usage


EDIT:

the total user cpu time is 43%

I think that you have ignored the %system(Percentage of CPU utilization for executing at the system(kernel) level. ) time. Try other tools like mpstat,iostat and sar for analyzing CPU utilization.

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Hi John, %system time was near 0. I'm trying to understand the discrepancy. Could it be a mis-configuration of the VM not reporting cpu usage correctly? –  Brig Jun 28 '11 at 18:59

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