More than one second of CPU in one second

[ModiDB2]

I've done 2 consecutive get snapshot for application with one second between.

I've seen that every once in a while although I get UOW Exec in the application state, the "Total User CPU Time used by agent (s)" counter does not increases and than after several seconds it increases in more than one second.

for example in 10 consecutive UOW Exec samples I get 9 samples with 0 "Total User CPU Time used by agent (s)" and in the 10 second I get 10 second of "Total User CPU Time used by agent (s)"

I've seen it in AIX, Sun and HP, usually in one cpu machines.

Does anybody familiar with this phenomenon? If so when does it happen?


Thanks,
Modi