Running latest Ubuntu 18.04 for NanoPi Duo with updates as of last night and CPU governor stays at ondemand even though I set it to conservative in /etc/default/cpufrequtils and reboot. CPU frequency settings do take effect, just not the governor.

With Xenial it was this way: https://github.com/armbian/build/issues/499 -- so I would assume with Bionic they do it now differently and we have to mask another service?

OK, I'll check for a init.d or systemd conf tonight when I get home and see if I can figure it out. I'll report back here.

OK, I did the following:

cat /etc/default/cpufrequtils
# WARNING: this file will be replaced on board support package (linux-root-...) upgrade
ENABLE=true
MIN_SPEED=240000
MAX_SPEED=1008000
GOVERNOR=conservative

sudo rm /lib/systemd/system/ondemand.service
sudo systemctl daemon-reload
sudo reboot

cpufreq-info -o
          minimum CPU frequency  -  maximum CPU frequency  -  governor
CPU  0       240000 kHz ( 20 %)  -    1008000 kHz ( 84 %)  -  conservative
CPU  1       240000 kHz ( 20 %)  -    1008000 kHz ( 84 %)  -  conservative
CPU  2       240000 kHz ( 20 %)  -    1008000 kHz ( 84 %)  -  conservative
CPU  3       240000 kHz ( 20 %)  -    1008000 kHz ( 84 %)  -  conservative