计算php页面执行时间

function getmicrotime(){
list($usec, $sec) = explode(" ",microtime());
return ((float)$usec + (float)$sec);
}

//放在需要开始计时的地方，计算整页放在开头
$time_start = getmicrotime();

//放在计时结束的地方
$time_end = getmicrotime();
$time = $time_end - $time_start;
echo "Page executed in $time seconds";