Perl Benchmarkモジュールで複数のサブルーチンをベンチマークする

#!/usr/local/bin/perl -w
use strict;
use warnings;

use Benchmark qw(timethese cmpthese);

sub doit1 {
	my $sum = 0;
	foreach my $i(1..10000) { $sum+=$i; }
	return $sum;
}
sub doit2 {
	my $sum = 1;
	foreach my $i(1..10000) { $sum*=$i; }
	return $sum;
}

timethese(50,{
	Doit1 => 'doit1',
	Doit2 => 'doit2',
	});

Benchmark: timing 50 iterations of Doit1, Doit2...
     Doit1:  1 wallclock secs ( 0.12 usr +  0.00 sys =  0.12 CPU) @ 400.00/s (n=50)
            (warning: too few iterations for a reliable count)
     Doit2:  0 wallclock secs ( 0.16 usr +  0.00 sys =  0.16 CPU) @ 304.76/s (n=50)
            (warning: too few iterations for a reliable count)

cmpthese(50,{
		Doit1 => 'doit1',
		Doit2 => 'doit2',
		});

        Rate Doit2 Doit1
Doit2 3.00/s    --  -22%
Doit1 3.86/s   29%    --