Re: Ampersands and sub speed

[chromatic]

It would surprise me if this were significant. You're not calling empty subroutines, so the time spent within the subroutines is likely more significant than the time spent calling the subroutines.

Even in those cases where the speed is significant, I wonder if, should it ever happen that you need to manipulate @_ before calling a function, the overhead of managing the array (actually the stack) dwarfs the gains of avoiding the stack manipulations.

[creamygoodness]

Since it turns out to be stack manipulation providing the savings, the cases where I'm going to be able to take advantage of the ampersand are few and far between.

cmpthese( -1, {
    k1 => sub { $foo->do_nothing(1) },
    k2 => sub { Foo->do_nothing(1)  },
    k3 => sub { Foo::do_nothing(1)  }, 
    k4 => sub { do_nothing(1)       },      
    k5 => sub { &do_nothing(1)      },      
});

        Rate   k2   k1   k5   k3   k4
k2 1380806/s   -- -14% -34% -35% -37%
k1 1610612/s  17%   -- -23% -25% -26%
k5 2103412/s  52%  31%   --  -1%  -4%
k3 2133262/s  54%  32%   1%   --  -2%
k4 2181254/s  58%  35%   4%   2%   --