Memcached et Can't get filling percentage

gistfile1.php

if ($memSize === null || $memUsed === null) {
    $mem = $this->_memcache->getstats();
    if (isset($mem['limit_maxbytes']) && $mem['limit_maxbytes'] > 0) {
        return ((int) (100 * ($mem['bytes'] / $mem['limit_maxbytes'])));
    } else {
        return 100;
    }
 
    //ne renvoie plus d'exception
    //Zend_Cache::throwException('Can\'t get filling percentage');
}