Disable THP and THP defrag on CentOS 7 EC2 instance

vcarel asked:

I want to disable transparent_hugepage (THP) on a CentOS 7 EC2 instance, which is enabled by default:

# cat /sys/kernel/mm/transparent_hugepage/enabled
[always] madvise never
# cat /sys/kernel/mm/transparent_hugepage/defrag
[always] madvise never

This setting can be manually changed:

# echo never > /sys/kernel/mm/transparent_hugepage/enabled
# echo never > /sys/kernel/mm/transparent_hugepage/defrag
# cat /sys/kernel/mm/transparent_hugepage/enabled
always madvise [never]
# cat /sys/kernel/mm/transparent_hugepage/defrag
always madvise [never]

… but the changes are lost after reboot.

I tried to put the echo never [...] instruction into my rc.local and cloud.cfg files, but it didn’t work.

I also tried to append the setting transparent_hugepage=never to the kernel line of /etc/grub.conf (as explained there), but it didn’t work better.

So… how can I disable THP on CentOS 7 running on an AWS EC2 instance ?

edit: changed title… I need to disable THP and THP defrag

My answer:

In addition to setting the grub command line, you also need to configure tuned. But not using the instructions you linked to, as they are so full of errors it would take half a day just to explain them all.

Create a custom tuned profile (which I’ll call custom), and then set the profile. You will base it on an existing profile, such as virtual-guest if you are running in a virtual machine (EC2 is, of course), or throughput-performance if you are on a physical machine.

Create the directory to hold the custom profile:

mkdir /etc/tuned/custom

Create the custom profile /etc/tuned/custom/tuned.conf, for example:



Now set the profile:

tuned-adm profile custom

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