Which file to set isolcpus on CentOS 7?

Question

I am using CentOS 7 and would like to isolate cores 0 and 1 for the OS/Kernel, meaning nothing will be scheduled on my other cores.

I need isolcpus

After some Googling I found this:

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/performance_tuning_guide/chap-red_hat_enterprise_linux-performance_tuning_guide-tuned

which says:

The following is an example of a custom profile that adds isolcpus=2 to the kernel boot command line:

[bootloader]
cmdline=isolcpus=2

So I presume I would add:

cmdline=isolcpus=0,1

However, I am unsure which exact file this must be done within. Could someone please clarify?