How to enable the two disabled CPU cores?

Autonomous Machines Jetson & Embedded Systems Jetson Nano
1

I have just received a Jetson Nano purchased directly from NVIDIA. After flashing jetbot_image_v0p4p0.zip to a micro SD and booting from it, I am finding only two of the four cores are enabled (and the system is noticeably sluggish). How do I enable the two disabled cores?

Here below what I am getting at present.

Thanks!

jetbot@jetson-4-3:~/.local/jetbot$ nproc
2
jetbot@jetson-4-3:~/.local/jetbot$ cat /proc/cpuinfo
processor : 0
model name : ARMv8 Processor rev 1 (v8l)
BogoMIPS : 38.40
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x1
CPU part : 0xd07
CPU revision : 1

processor : 1
model name : ARMv8 Processor rev 1 (v8l)
BogoMIPS : 38.40
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x1
CPU part : 0xd07
CPU revision : 1

2

To enable 4 cores:

sudo nvpmodel -m 0

No reboot needed

To go back to 2 cores:

sudo nvpmodel -m 1

Power modes are listed in /etc/nvpmodel.conf

My understanding is that power mode 0 (4 cores) can draw more that 5W, which is as much as the board can get from the power source connected to the USB port, which is what is likely to be used when running the board from batteries.

When running the Nano from batteries, the CPU power must therefore be reduced by more than half (power mode 1 also limits the max clock).