It's kind of funny, runrig even mentioned that when benchmarking you should exclude operations that don't concern the thing you are trying to test, yet every single example called their "perl_and/mod" function for one operation. Don't you think the function call from timethese/timeit to perl_and/mod is taking time?

So I did it this way: 

 
sub perl_mod { 
  for my $z (1..10_000) { 
    $_[0] % 2; 
  } 
} 
 
sub perl_and { 
  for my $z (1..10_000) { 
    $_[0] & 1; 
  } 
} 
 
timethese(10_000, { 
                       perl_mod => sub { perl_mod($num) }, 
                       perl_and => sub { perl_and($num) }, 
                      });

[download]

and got the following results: 

nicholas(/5)@neko [106 /<1>nicholas/tmp] > ./time
Benchmark: timing 10000 iterations of perl_and, perl_mod...
  perl_and: 210 wallclock secs (209.32 usr +  0.79 sys = 210.11 CPU)
  perl_mod: 260 wallclock secs (258.62 usr +  0.93 sys = 259.55 CPU)
nicholas(/5)@neko [107 /<1>nicholas/tmp] >

[download]

Which shows the perl_and to be around 20% faster than perl_mod: about what I would expect.

Then, I did a pure C test: 

#include <stdio.h>

void c_and(int i) {
  int a;
  for (a=0;a<10000;a++) {
    i & 1;
  }
}
void c_mod(int i) {
  int a;
  for (a=0;a<10000;a++) {
    i % 2;
  }
}

int main(void) {
  int a;
  for (a=0;a<100000;a++) {
    c_and(a);
  }
  //for (a=0;a<100000;a++) {
  //  c_mod(a);
  //}
  exit(0);
}

[download]
and ran it seperately for each of the types (I was using /bin/time to test): 

For c_and:
29.800u 0.040s 0:29.84 100.0%   0+0k 0+0io 69pf+0w

[download]
and 
for c_mod:
29.540u 0.390s 0:29.99 99.7%    0+0k 0+0io 69pf+0w

[download]

Which again shows and to be faster, though no wheres as much of a difference as with perl (I presume gcc is optimized).

test platform: dual PII-233 with a load avg of around 7 :)

In reply to Re: Testing a number for oddness by mr.nick
in thread Testing a number for oddness by Falkkin

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