php源码之判断网络速度

php判断/计算网络速度，源码如下： 

<?php
$kb=10240;
echo \"streaming $kb Kb...<!-\";
flush();
$time = explode(\" \",microtime());
$start = $time[0] + $time[1];
for($x=0;$x<$kb;$x++){
    echo str_pad(\'\', 1024, \'.\');
    flush();
}
/*  http://www.manongjc.com/article/1422.html */
$time = explode(\" \",microtime());
$finish = $time[0] + $time[1];
$deltat = $finish - $start;
echo \"-> Test finished in $deltat seconds. Your speed is \". round($kb / $deltat, 3).\"Kb/s\";
?>