use Benchmark qw/cmpthese/;

$dir = "test";
opendir DIR, "< $dir";

cmpthese(1000, {
  'grep' => sub {
               opendir DIR, "$dir" or die "Unable to open dir : $!\n";
               @list=grep(!/^(\.+?)$/,readdir(DIR));
               closedir DIR;
            },
  'while' => sub {
               opendir DIR, "$dir" or die "Unable to open dir : $!\n";
               while (readdir(DIR)) {
                 push @list, $_ unless /^(\.+?)$/;
               closedir DIR;
               }
             }
});