stinky.blog

Reducing power consumption of Proxmox nodes

I noticed the other day that my proxmox nodes are running at max turbo frequency all the time. Even when there is virtually zero activity, the 8700 and 7700k are sitting at 4.2ghz+ on all cores. The little x270 stays locked at 3.4ghz on its two cores. Since these servers idle a huge amount, they really don’t need to be at max turbo constantly. I saw it recommended on the Proxmox forum to change the cpu governor. Does it work?

Let's measure the power consumption. #

First, we need to install linux-cpupower

apt install linux-cpupower

Then we can run turbostat to get a rough idea:

turbostat –quiet –show Package,Busy%,Bzy_MHz,PkgTmp,PkgWatt,CoreTmp –interval 5

With the default governor, my i7-8700 was idling at around ~8.2 watts according to "PkgWatt".

Let's change the cpu governor #

Changing the governor is pretty easy:

echo “powersave” | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

Now run the turbostat command again to see how the cpu frequency and power consumption have changed.

My i7-8700 is now idling around ~2.9 watts according to "PkgWatt".

Pretty nice reductions! Haven’t noticed any changes in performance for my normal services, since the turbo just ramps back up as expected when you apply a load.

You can revert the change back to default easily:

echo “performance” | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

To make this setting persist on reboot: #

You need to add a line to your crontab. Open up the root user's crontab:

crontab -e

and add the following line at the bottom:

@reboot echo "powersave" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

Save and reboot to test it. Happy homelabbing!

Happy homelabbing!