in reply to Re^3: Performance, Abstraction and HOP
in thread Performance, Abstraction and HOP

So if Perl's function calls are "too slow" (whatever that means, and nobody in this thread has suggested any relevant meaning) 
~/perl$ cat func_test.pl 
#!/usr/bin/perl 

#sum of number between 1 and 1,000,000
$n = 1_000_000;

print addup($n, 0);

sub addup
{
    return $_[1] if !$_[0];
    return addup($_[0]-1,$_[1]+$_[0]);
}

~/perl$ cat loop_test.pl 
#!/usr/bin/perl 

#sum of number between 1 and 1,000,000
$n = 1_000_000;
$sum = 0;

$sum += $n-- while($n);


~/perl$ time ./func_test.pl 
500000500000
real    0m4.025s
user    0m3.568s
sys     0m0.455s

~/perl$ time loop_test.pl  

real    0m0.390s
user    0m0.388s
sys     0m0.001s

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Re^5: Performance, Abstraction and HOP
by runrig (Abbot) on Sep 14, 2005 at 22:21 UTC
    I'm not sure that a memory hogging recursive function makes for a fair benchmark of function calling speed (even if the tail recursion could be optimized away in another language -- and if the tail recursion could be optimized away, you wouldn't be calling the function anymore, you'd just be doing a goto). I think this version of func_test.pl is more fair (which attempts to test the speed of function calling rather than memory allocation):
    #!/usr/bin/perl

#sum of number between 1 and 1,000,000
$n = 1_000_000;

my $t = 0;

$t = addup( $t, $n-- ) while $n;
print "$t\n";

sub addup
{
    $_[0] + $_[1];
}

    [download]
    and then the two come out closer:
    $ time ./func_tst.pl
500000500000

real    0m5.68s
user    0m5.48s
sys     0m0.02s
$ time ./loop_test.pl
500000500000

real    0m1.48s
user    0m1.47s
sys     0m0.01s

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