PHP服务器负载判断

<?php
header("content-type:text/html;charset=utf-8");

// echo PHP_OS;exit;
// echo get_server_load();
var_dump(sys_getloadavg());

/*
$load = sys_getloadavg();
if ($load[0] > 80) {
    header('HTTP/1.1 503 Too busy, try again later');
    die('Server too busy. Please try again later.');
}
*/

// 建议最大负载不要超过3*N核，例如有16核（含8核超线程）则 16*3=48
function get_server_load() {

    if (stristr(PHP_OS, 'win')) {

        $wmi = new COM("Winmgmts://");
        $server = $wmi->execquery("SELECT LoadPercentage FROM Win32_Processor");

        $cpu_num = 0;
        $load_total = 0;

        foreach($server as $cpu){
            $cpu_num++;
            $load_total += $cpu->loadpercentage;
        }

        $load = round($load_total/$cpu_num);

    } else {

        $sys_load = sys_getloadavg();
        $load = $sys_load[0];

    }

    return (int) $load;

}