You could get the timestamp at the beginning of the perl script, and then get the timestamp at the end of the perl script, and then print out the difference (use the time function in Perl). If you need to measure the difference very accurately (i.e. less than one second), you can use
the Time::HiRes module, or if you have gettimeofday(2), you may be able to use the syscall interface of Perl. Here's the link to the Perl FAQ which explains how to do it :