http://cued.xunlei.com/log031
http://www.zhangxinxu.com/wordpress/2012/03/%E5%A4%9A%E6%A0%8F%E5%88%97%E8%A1%A8%E5%8E%9F%E7%90%86%E4%B8%8B%E5%AE%9E%E7%8E%B0%E7%9A%84%E7%80%91%E5%B8%83%E6%B5%81%E5%B8%83%E5%B1%80-waterfall-layout/
