The Benchmark module should do what you need. Ex:

use Benchmark;

my $start_time = new Benchmark;
# do your processing
my $end_time = new Benchmark;
my $execution_time = timediff($end_time, $start_time);
print timestr($execution_time);
[download]

Sample output:

4 wallclock secs ( 3.64 usr +  0.00 sys =  3.64 CPU)

You could easily extract the information you need from this string.

See perldoc benchmark for more info...