Disable SELinux

Check current status:

cat /selinux/enforce

1 => enabled

0 => disable

To disable SELinux:

• Disable immediately withoput reboot, change will be lost upon reboot:
  echo 0 > /selinux/enforce
• Reboot required:
  • Set selinux=disabled in /etc/selinux/config, then reboot
  • In grub boot command-line add: selinux=0, and reboot

[Ref] Excellent post with details available here

Linux Clock Source

There are various clock-sources available in Linux. It is important to select the right one for keeping a correct system clock, or to reduce time drifts and keep the system time in sync with a time source. Which clock-source you choose can affect performance too.

A good starting point is to determine which clocksources are available on your system and which one is currently in use.

cd /sys/devices/system/clocksource/clocksource0/
cat available_clocksource
cat current_clocksource

Excellent brief primer on various clocks: http://the-b.org/Linux_timers