clearly the massive differences between
tin2 and
tin3 must at least alert you that something is wrong with the benchmark...
Frankly I have no idea what goes on once you start eval-ing strings in the Benchmark module, but from the presented examples, something seems suspicious.
Here is a benchmark by me
use Benchmark qw(cmpthese);
my @arr = map {rand} 0..900000;
my @output = map {rand} 0..300000;;
Benchmark::cmpthese(10,{
tin1 => sub {
$output[int($_/3)] += $arr[$_] for 0..@arr-1;
},
tin2 => sub {
$output[$_] = $arr[3*$_] + $arr[3*$_+1] + $arr[3*$_+2]
for 0..@arr/3;
},
tin3=> sub {
my $b = 0;
for (0..@arr /3) {
$output[$_] = $arr[$b] + $arr[$b+1] + $arr[$b +2];
$b += 3;
}
}
});
With result
$ perl ../../../perlmonks/bench-trip.pl
Rate tin1 tin2 tin3
tin1 1.81/s -- -41% -46%
tin2 3.08/s 70% -- -9%
tin3 3.39/s 87% 10% --