protected function aggregateCpu($processes)
    {
        $cpus = array();

        foreach ($processes as $process) {
            if (isset($cpus[$process->getName()])) {
                $cpus[$process->getName()] += $process->getCpu();
            }
            else {
                $cpus[$process->getName()] = $process->getCpu();
            }
        }

        return $cpus;
    }