time measurement

[John Leimon]

To what degree of precision can we measure the clock as end-user
programmers. I have found the functions nanotime and microtime but they are
restricted to kernel development only. I know realtime linux has a
microtime function availible for the user base. Is there an api or non
kludgy method for doing some time measurements in the order of microseconds
or even nanoseconds??

  John