public function getSwapFree()
    {
        if (count($this->_swapDevices) > 0) {
            $free = 0;
            foreach ($this->_swapDevices as $dev) {
                $free += $dev->getFree();
            }

            return $free;
        }

        return null;
    }
public function getSwapFree()
    {
        if (count($this->_swapDevices) > 0) {
            $free = 0;
            foreach ($this->_swapDevices as $dev) {
                $free += $dev->getFree();
            }

            return $free;
        }

        return null;
    }
public function getSwapFree ( ) { if ( count ( $ this -> _swapDevices ) > 0 ) { $ free = 0 ; foreach ( $ this -> _swapDevices as $ dev ) { $ free += $ dev -> getFree ( ) ; } return $ free ; } return null ; }
Returns total free swap space

@see System::_swapDevices
@see DiskDevice::getFree()

@return Integer
Returns total free swap space