Re: perl printf vs C fprintf performance

I used the following code to benchmark, in an attempt to reduce the comparison solely to the actual printf calls:

use warnings;
use Benchmark qw(cmpthese);
open OUTF, '>', '/dev/null' or die "/dev/null: $!\n";
cmpthese(0, {
  perlprint => q{
    for my $j (0 .. 255) {
      printf OUTF "host DAAA%02X { blah blah XX:XX:XX:%02X; }\n", $j, 
+$j;
    }   
  },
  Cprint => q{
    for my $j (0 .. 255) {
      C_print(*OUTF, $j);
    }
  },
});

use Inline 'C' => <<INLINE;
void C_print(FILE *fp, int j) {
  fprintf(fp, "host DAAA%02X { blah blah XX:XX:XX:%02X; }\n", j, j);
}
INLINE
[download]

This consistently reported the C code as being about twice as fast as the perl code (on my perl-5.8.5 installation), which seems about reasonable to me given all the extra layers of indirection the perl code has to wade through.

One of the differences between perl-5.6.x and perl-5.8.x is that the 'perlio' abstraction is now the default, and with perlio enabled we get to take advantage of some of the lower-level I/O mechanisms available to the C library fprintf. It is possible that switching to a perl built with 'perlio' will get you a factor closer to this - check for "perlio=define" in the perl -V output.

Hugo

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Re^2: perl printf vs C fprintf performance by decnartne (Beadle) on Mar 15, 2005 at 14:23 UTC
...thx for the explanation decnartne ~ entranced	[reply]
Re^2: perl printf vs C fprintf performance by Leotrillo (Initiate) on Nov 02, 2009 at 21:58 UTC
Hi, my name is Leo an i have the same problem, is very slow to open some document to write in it. you comment "It is possible that switching to a perl built with 'perlio' will get you a factor closer to this - check for "perlio=define" in the perl -V output." Can you put some examples to see how i can to accelerate this r/w docs in perl? thank you.	[reply]
Re^3: perl printf vs C fprintf performance by Anonymous Monk on Nov 03, 2009 at 04:32 UTC
useperlio is an option you set when compiling/installing perl http://search.cpan.org/dist/perl/INSTALL `$ perl -V \|grep -i perlio useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=und +ef USE_LARGE_FILES USE_PERLIO USE_SITECUSTOMIZE $ perl -V:useperlio useperlio='define';` [download]	[reply] [d/l]