Oracle Linux（RHEL）6.6性能非常糟糕 - 发生了什么？

I have a problem with Oracle Linux 6.6 (Red Hat Enterprise Linux). The performance is very poor, due to heavy disk usage. The CPU usage is normal on idle systems, but disk works so hard, that even writing file edited in VIM takes a lot of time. The only strange thing I observed is "Permission denied" to some processed (e.g. yum background process) trying to access files in /proc. Could this be a reason for that bad performance? What could I do do make this work?I have a problem with Oracle Linux 6.6 (Red Hat