Transparent Huge Pages – OEL 6.5

This is a very short post to show that THP (or Transparent Huge Pages) was indeed removed from OEL 6.5 (UEK3 kernel – version 3.8.13-16.2.2.el6uek.x86_64) just like Martin Bach noticed in this post.

Transparent Huge Pages have been discussed since its introduction (kernel 2.6.37) in Oracle community mainly because of several performance issues and node reboots. My Oracle support has a good note alerting DBAs to disable the THP to avoid problems.

In the past i’ve showed using a very simple bash script how to check if any Oracle background process is allocating any THP:


for i in $(ps -eo pid,cmd | grep ora_ | grep -v grep | awk '{split($0,a," "); print a[1]"|"a[2]}')
   PID=$(echo $i | awk '{split($0,a,"|"); print a[1]}')
   PNAME=$(echo $i | awk '{split($0,a,"|"); print a[2]}')
   THP=$(cat /proc/$PID/smaps | grep AnonHugePages | awk '{sum+=$2} END  {print sum}')

   echo "PID "$PID "(" $PNAME ") is using " $THP "Kb of THP"


After the update to OEL 6.5 (code name Santiago 😉 and UEK3 kernel version (3.8.13-16.2.2.el6uek.x86_64) the result is that THP was removed. I’ve used Oracle 12c ( for this little essay.

[root@baco scripts]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.5 (Santiago)

[root@baco scripts]# uname -a
Linux baco 3.8.13-16.2.2.el6uek.x86_64 #1 SMP Tue Nov 26 08:41:44 PST 2013 x86_64 x86_64 x86_64 GNU/Linux


[root@baco scripts]# grep -i AnonHugePages /proc/meminfo | wc -l

Screenshot 2013-12-07 18.19.35

Now you don’t have to worry about the not-so-good-for-Oracle THP. Now installing DTrace 🙂


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