use Benchmark qw( cmpthese );
our $KEY="df";

{
	local $/;
	open my $hosts,'/etc/hosts';
	$_= <$hosts>;
	close $hosts;
}
$_= $_ x (0.5*1024*1024 / length $_);
s/$KEY/XX/g;
$_.= "\n    df   ";

print length $_,"\n";


cmpthese(-3, {
   caret => '/^ \s* $KEY /mx',
   cr => '/\n \s* $KEY /mx',
});