Comment 29 for bug 493156

According to SRU policy no new features can be added to a kernel without a feature exception. The other prime directive of the SRU policy is to add no regressions. Given the amount of code that this config option enables, I chose the path of least risk while still providing the ability for savvy users to enable task delay accounting.

So, yes, you will have to modify your grub boot command line. If using grub2, then I suggest adding it to /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT. Remember to run update-grub afterwards.