Please see the following page for detailed explanations.
http://www.jetsonhacks.com/2017/03/25/nvpmodel-nvidia-jetson-tx2-development-kit/


You can change the power model of Jetson TX2 with the nvpmodel command as shown on the above page, and its configuration is defined in the /etc/nvpmodel.conf file.
In order to enable 2 Denver cores with the MAXP_CORE_DENVER setting, it is necessary to modify the /etc/nvpmodel.conf file as follows.


< POWER_MODEL ID=4 NAME=MAXP_CORE_DENVER >

cpu core settings
/sys/devices/system/cpu/cpu1/online 1
/sys/devices/system/cpu/cpu2/online 1 ←Change from 0 to 1
/sys/devices/system/cpu/cpu3/online 0
/sys/devices/system/cpu/cpu4/online 0
/sys/devices/system/cpu/cpu5/online 0


The correspondence between the CPU number and each core is as follows.

CPU core
CPU0 A57 Master core (always enabled)
CPU1 Denver2
CPU2 Denver2
CPU3 A57
CPU4 A57
CPU5 A57