Reference: times

times

times

Returns a four-element list giving the user and system CPU times, in seconds (possibly fractional), for this process and for the children of this process:

($user, $system, $cuser, $csystem) = times;

For example, to time the execution speed of a section of Perl code:

$start = (times)[0];
...
$end = (times)[0];
printf "that took %.2f CPU seconds\n", $end - $start;