RZ/G2 Kernel and Linux FAQ
You can enable and disable CPU cores by wrriting to a sysfs value.
This is helpful for when you want to experiment with the performance of your application if you were to use a processor with less CPU cores.
For example, this command will disable the 2nd core.
$ echo 0 > /sys/devices/system/cpu/cpu1/online
More detailed information can be found here: https://www.cyberciti.biz/faq/debian-rhel-centos-redhat-suse-hotplug-cpu