I wrote a post a couple of months ago called
Which version of Oracle Linux should I pick for Oracle server product installations? One of the points I raised was the use of UEK allows you to have all the latest kernel goodies, regardless of being on an older release, like OL6.
I saw a post today about the release of UEK4, so now you have access to all the improvements in the 4.1 mainline Linux kernel, whether you are on are running OL6 or OL7. That just goes to prove the point really.
If you are running RHEL, you might be feeling pressure to move from RHEL6 to RHEL7 to get a bunch of the kernel enhancements that came with it. If you are running OL6, just switch to UEK4 and your kernel is ahead of the RHEL7 kernel. No stress and no having to deal with systemd and firewalld. 🙂