【紧急】系统每天访问人数800万左右，数据库频繁报连接池达到最大错误

　　现在维护的公司系统每天访问人数800万左右，在数据库连接的时候，数据库频繁报连接池达到最大错误。.net 默认连接池100，也设置了连接池到512个，但是并没有解决问题，依然报连接池达到最大，请高手指点。

错误如下：      

A SimpleSql Save Exception Ocurred: Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.