Potential mitigations for CPU throttling (thermal heating)

[tdurand]

Problem

Life is unfair 😁 .

I was happily running OpenDataCam and playing with it in the street.. and after 2 min I noticed some FPS drops (from 20-17 FPS to 15 FPS).. and then from 15 to 12, and then from 12 to 9 FPS (this is 10 min time), it was like 25ºC temperature in the afternoon

My first though was "shit" Node.js dependency is affecting long term run.. but then I did the test with the "native" benchmark app.. and got the same problem

The issue is caused by CPU thermal throttling . which is well known to game developer on mobile also.. The device overheats and then the CPU need to throttle to avoid damages..

I ran a benchmark over 15 min time: https://play.google.com/store/apps/details?id=skynet.cputhrottlingtest&hl=fr&gl=US this morning (temperature more like 16ºC outside), and it holded up way better...

What can we do about it ?

• Try to better cool the device .. I'm gonna order a mobile ventilator [like this](https://www.amazon.com/Semiconductor-Refrigeraci%C3%B3n-Tel%C3%A9fono-Ventilador-Radiador/dp/B088R5H1RQ to see if this helps) and see if it works

• Test , test and test and get an idea of the real performance achievable depending on outside temperature / cooling / CPU raw performance ..

• Add alert to the user in the app that the performance are dropping cause of CPU throttling and he should cool the device to keep max perf.. there is an API for this: https://developer.android.com/ndk/reference/group/thermal

• Investigate NCNN settings / android settings .. is it possible to have a "constant FPS" mode that does not use the CPU full speed but rather prioritize to be consistent for several hours etc etc.. Implement multithreading independent of OpenMP Tencent/ncnn#1901 (comment) ??

[tdurand]

I bought a little fan for android: https://www.amazon.com/gp/product/B07V1RHRC7/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1, and seems to help, perfomance don't degrate below 80% in the 15 min run.

So keeping the phone cool is definitely the solution here.

[b-g]

😂! Unbelievable what kind of gadgets are around. Should I get one too?

[tdurand]

yes 😎.. I mean it's not the best but it really seems to help.. And yes, I just ordered one for you to put on your christmas tree 🎄😂

[b-g]

Cheers! 🎄🎢