Greetings honorable Monks,

I am doing some massive data processing, and in my quest for additional speed I wrote the following to check how well does perl actually perform: 
use Benchmark qw(:all);

my $a = 10;
my $b = 20;

cmpthese(-2, {
        'Direct' => sub {
            my $c = $a+$b;
        },
        'Sub' => sub {
            my $c = add ($a, $b);
        },
        'Method' => sub {
            my $c = __PACKAGE__->meth_add ($a, $b);
        },
        'Method+sub' => sub {
            my $c = __PACKAGE__->meth_sub_add ($a, $b);
        },
        'Sub^2' => sub {
            my $c = add2 ($a, $b);
        },
        'Method^2' => sub {
            my $c = __PACKAGE__->meth2 ($a, $b);
        },
    });

sub add {
    return $_[0] + $_[1];
}

sub add2 {
    return add (@_);
}

sub meth_add {
    shift;
    return $_[0] + $_[1];
}

sub meth_sub_add {
    shift;
    return add (@_);
}

sub meth2 {
    return $_[0] -> meth_add ( $_[1], $_[2] );
}

[download]
And here are the results I get: 
                Rate Method^2 Method+sub     Sub^2    Method       Sub    Direct
Method^2    500713/s       --       -22%      -37%      -44%      -58%      -91%
Method+sub  643967/s      29%         --      -19%      -27%      -46%      -88%
Sub^2       797484/s      59%        24%        --      -10%      -33%      -85%
Method      886331/s      77%        38%       11%        --      -26%      -84%
Sub        1191561/s     138%        85%       49%       34%        --      -78%
Direct     5397078/s     978%       738%      577%      509%      353%        --
Now I understand how method dispatch works and why it is slow, but I do not understand why subroutines suffer almost the same penalty. Is there some kind of perl compile flag, or some hidden optimization that can improve these numbers (which _really_ add up in a complex code flow)?

Thanks

Peter

In reply to Performance issues with subroutines/methods by ribasushi

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