setitimer/getitimer

[Rilo Nauman]

I use calls to setitimer and getitimer to
measure runtimes of C-Code. These timers 
provide three different types of runtimes:
ITIMER_REAL, ITIMER_VIRTUEL, ITIMER_PROF.
I would like to know what's the difference
between the last two, and what exactly is
measured by this timers.
Especially I need to know if swapping and
scheduling-operations are included in these
timers or not.
Can anybody exactly tell me what is measured ?
The manual isn't very precise in that point.

Thanks in advance !

Please respond to
rn at informatik.uni-kiel.dbp.de

Rilo Naumann