Retired Recognized Developer
The way I understand the AOS usage is that it represents % of battery drain.
Say you charge your phone to 100 and start using it non stop for 2 Hrs.
The main drain will be screen cpu and maybe network or the app you are using.
In that case, AOS will be almost nothing, like 5%. But your battery will have dropped to , say, 70%
Now charge your phone again, and leave it on standby for as many hours requested to get 70% of battery left. This would need many hours.
Obvioulsy, because you did nothing with the phone, the main drain there is the OS itself!
So to compare the old and the new kernel, they have to be tested the same way.
Say start with a full charge before going to bed and set an alarm in 8hrs after you unplug the phone.
Leave the phone on standby for 8Hrs and check the AOS usage after those 8Hrs.
Next night, repeat the process with the new kernel and see if there is any difference.