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 usageComprehending '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.
