CakePHPのセッション周りの設定

AppController

function beforeFilter() {
    CakeSession::$requestCountdown = 1;
}

core.php

Configure::write('Session', array(
        'defaults' => 'php',
        'timeout' => 1440,
        'autoRegenerate' => true,
        'ini' => array(
            'session.cookie_lifetime' => 0,
            'session.gc_maxlifetime' => 86400,
            'session.gc_probability' => 1,
            'session.gc_divisor' => 100
        )
    ));

参考：http://hibiki30nen.blogspot.jp/2012/10/cakephp.html
参考：http://artisanedge.jp/blog/2012/11/21/223145.html