PHP implementation to calculate the size of a folder

function dirSize($directoty){
	$dir_size=0;
	if($dir_handle=@opendir($directoty))
	{
		while($filename=readdir($dir_handle)){
			$subFile=$directoty.DIRECTORY_SEPARATOR.$filename;
			if($filename=='.'||$filename=='..'){
				continue;
			}elseif (is_dir($subFile))
			{
				$dir_size+=dirSize($subFile);
			}elseif (is_file($subFile)){
				$dir_size+=filesize($subFile);
			}
		}
		closedir($dir_handle);
	}
	return ($dir_size);
}
$dir_size=dirSize("xym");
echo round($dir_size/pow(1024,1),2)."KB";

PHP