Unix timers ...

Timer	can show CPU used time	can show "wall" clock time	resolution on Solaris 8
getrusage()	yes	no	10 millisec
gettimeofday()	no	yes	1 microsec

Links:

POSIX Interval Timers tutorial by Michael Lemmon , or try google search for sigev_notify Keywords: sigev_notify
"Signals and Timers" tutorial by Michael Lemmon Here