u/electrobento

TL;DR: Check your CPU governor setting. It could be set to a mode with no scaling or at a reduced frequency, which can reduce performance, reduce energy efficiency, and/or increase heat unnecessarily.

I've been working on tuning my Banana Pi R4 SQM performance and today noticed that the CPU governor in the vanilla mainline OpenWRT build is set to "userspace" at a static 1.5GHz frequency. The range of the Filogic 880 in this device is at least 800MHz to 1.8GHz, meaning theoretically, at defaults, I'm using more electricity than needed and am also not able to tap the full potential of the CPU.

Note: in my testing with a Kill-A-Watt, there is no measurable difference in electricity usage between 1.5Ghz and 800Mhz, but on whatever device you're using, this could be a totally different story. However, dropping it down to allow scaling to 800MHz dropped core temps by 1 degree Celsius, so why not.

Easy check and fix for your device

1. SSH in to your device
2. Check the current governor. In my case, it was "userspace" at a static 1.5GHz
   1. cat /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
3. List the available governors
   1. cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_governors
4. Set to your desired setting (I switched to "schedutil" which will scale as needed, up to the full 1.8Ghz)
   1. echo "schedutil" | tee /sys/devices/system/cpu/cpufreq/policy*/scaling_governor
5. Make it persistent
   1. Add the command from Step 4 to your /etc/rc.local

I snagged a Banana Pi R4 off of eBay for $80. This is an excellent price at least for today.

Unfortunately, I learned that the USB C port is a bit detached. It is connected and works, but the stabilizers on the side are no longer attached, so it’s really close to coming off altogether.

Given the high prices of high-performance OpenWRT-compatible routers today, I’m having a hard time deciding if I should send it back. Of course, I could buy a barrel power adapter and move on, but I’d still prefer to use USB C if possible (since I wouldn’t need to buy anything more).

Anyone else had an issue like this? Not interested in doing any soldering, but maybe there‘s a simple solution here.