毫秒级别的时间差

eg:

//开始时间

list($t1, $t2) = explode(' ', microtime());

$st = (float)sprintf('%.0f', (floatval($t1) + floatval($t2)) * 1000);

//休息10s

sleep(10);

//结束时间

list($t1, $t2) = explode(' ', microtime());
$et = (float)sprintf('%.0f', (floatval($t1) + floatval($t2)) * 1000);

//相差时间

$endtime = $et-$st ;