Interesting concern. I show that each call takes only about 1usec on a PIV 1.8GHz and about 0.4usec on a 1GHz Athlon. Here is a page which has more exact methods for doing it in assembly ... http://www.ncsa.uiuc.edu/UserInfo/Resources/Hardware/IA32LinuxCluster/Doc/timing.html#linuxasm Good luck. On Fri, 30 Aug 2002, Mike Bresnahan wrote: > Thanks, Chris. My concern with using gettimeofday() is that I don't want to > pay the performance cost of doing a timezone calculation. In fact I don't > require the real time. I simply want to measure the elapsed time of an > operation. A simple counter running at the clock frequency of the processor > would suffice; as long as I can also determine the clock frequency. I > understand that the pentium processor has such a function and it requires > only a small amount of assembly code to access it, however I'd prefer to not > write the assembly code if I don't have to. -Chris McKinley finger lamfada at lugh.net for GPG key